Topic Tag: AVI30316

Part 2 – Aeronautical Documents, Charts, & Operations

Aim

To gain an understanding of the aeronautical documentation and charts that an pilot of an unmanned aircraft is required to understand when operating within Australia.

Objectives

At the end of this briefing you will be able to:

  • Have a basic understanding of how to read aeronautical documents and charts.
  • Understand the importance of correctly interpreting meteorological information before undertaking a mission.
  • Use aeronautical documents to conduct desktop assessment of the viability of potential UAV operating sites.

Aeronautical Documents

Required Aeronautical Documents

  • Charts
    • Planning Chart – Australia
      • Acronym: PCA
      • Type: Lambert Conical Projection
    • En-route Chart – Low
      • Acronym: ERC-L
      • Type: Lambert Conical Projection
    • Visual Navigation Chart
      • Acronym: VNC
      • Type: Lambert Conical Projection
    • Visual Terminal Chart
      • Acronym: VTC
      • Type: Mercator Projection
  • En-route Supplement – Australia
  • Notice to Airmen (NOTAM)
  • Aeronautical Information Publication – Supplements & Information Circulars

Charts

Any point on the surface of the earth can be precisely referenced in terms of a latitude and longitude.

Meridians of longitude are half ‘great circles’, perpendicular to the equator, that extend from pole to pole. The meridians are identified by the angle that they subtend, at the centre of the Earth, with the prime meridian. That angle is measured in degrees, minutes and seconds east or west from the prime meridian – the Greenwich Observatory, England.

Parallels of latitude are circles drawn around the Earth starting from the equatorial plane, north and south of the equator and parallel with it and reducing in circumference toward the poles. For our purposes we can say that the parallels appearing on aviation charts are identified by the angle that they subtend with the equatorial plane, i.e. they are geodetic, measured in degrees, minutes and seconds and whether they lie north or south of the equator.

Measurements

One “nautical mile” is the length, at the Earth’s mean sea level surface, of one minute of arc of a great circle.

The International Nautical Mile is 1852 metres or 6076.1 feet. Consequently, one degree of latitude (measured along a meridian) has an equivalent surface distance of 60 nautical miles, and one second of latitude is about 31 metres, while 1/100th of a second is about 0.3 metres.

A “knot” is a speed of one nautical mile per hour.

Latttitude and longitude coordinates (“lat/long“) are expressed with the direction from the equator/prime meridian first (e.g. S and E), then numbers representing the degrees followed by numbers for the minutes. The symbols for degrees and minutes are omitted, e.g. S36 44.1 E147 10.2.

This is the standard format for geographic locations in ERSA.

Recommended VFR Charts – Planning Chart Australia

Planning Chart Australia (PCA) is designed to assist in initial VFR flight planning.

The PCA is a single sheet showing the coverage of the World Aeronautical Charts, the meteorological area forecast (ARFOR) boundaries, the estimated FIS VHF coverage from both 5000 feet AMSL and 10 000 feet (but not the frequencies), and the areas without FIS VHF coverage. The FIS HF communication frequencies are shown. The spot location of about 700 named airfields is indicated

PCA is designed to assist in initial VFR flight planning and it is amended semi-annually. It is of rather limited use in initial planning of flights below 5000 feet (i.e. most ultralight flights) in eastern Australia because straight-line tracks between departure point and destination may be precluded because of the topography, and there are no indications of such on the PCA.

Recommended VFR Charts – World Aeronautical Charts

The 43 Australian World Aeronautical Charts (WACs) are small scale (1:1,000,000 or 1mm=1km), derived from aerial photography, and designed for pre-flight planning and flight. They are part of an ICAO international series. They do not indicate Control Zone (CTR) or  Prohibited, Restricted and Danger areas (PRD), nor is there any Flight Information Area (FIA), radio communications or radionavigation information.

Each WAC chart generally covers 6° of longitude and 4° of latitude. Sheet dimensions are about 70 × 60 cm and the scale is such that a real distance of one nautical mile is represented by less than 2 mm on the chart; thus WACs are really not suited to low-altitude navigation in slow aircraft.

Recommended VFR Charts – Visual Navigation Charts

Visual Navigation Charts (VNCs) are a larger scale (1:500,000) and show airspace information and FIS detail laid over the topographic base.

VNC charts contain the following airspace detail:

  • CTR, CTA dimensions and lower levels.
  • Flight Information Area and Surveillance Information Service boundaries where available.
  • Flight Information Service and Surveillance Information Service frequencies and providers
  • Communication and navigation aid frequencies for licensed airfields
  • PRD and designated & remote areas.

There are only 15 VNCs, those available covering the more populous areas of Australia — Tasmania to North Queensland, plus areas around Perth, Adelaide, Darwin and Tindal.

Recommended VFR Charts – Visual Terminal Charts

Approximately 25 Visual Terminal Charts (VTCs) charts provide both aeronautical and topographic information around major airports at a scale of 1:250,000.

They are essential for VFR operations in the vicinity of such airports to avoid violating controlled airspace.

The charts are based on the NATMAP 250K series maps and use the Universal Transverse Mercator [UTM] projection but with a latitude/longitude graticule rather than the normal UTM grid

Their dimensions are around 90 × 50 cm and show the following details:

  • PRD areas.
  • CTR and associated CTA dimensions including the lower levels of the CTA steps surrounding the airport, lanes of entry, ATC check points.
  • Surveillance Information Service frequencies where available.
  • Communication and navigation aid frequencies for licensed airfields.
  • VFR approach points.

Recommended VFR Charts – En Route Chart (Low-Level)

The En Route Chart (Low-Level) (ERCLO) series is drawn to various scales to accommodate significant air traffic route areas and shows controlled airspace, PRD areas, air routes and segment distances, ATS and radio-navigation services, ATS frequencies and location, plus communication and navigation aid frequencies for licensed airfields — but no topography.

It also indicates those airfields where VHF radio contact with FIS is possible from the ground.

The FIS area boundaries are shown together with an information box showing the provider of the flight information service (e.g. Brisbane Centre), the frequency and the location of the area transceiver. 
The series of eight sheets cover Australia and are intended primarily for IFR flights conducted below 20 000 feet.

Map Topography

Aircraft operating under the VFR must navigate by visual reference to the ground. To assist this visualisation, WACs and VNCs display tinted topographic contours signifying surface areas between the 660 feet (200 m) and 1639 feet elevations, 1640+ feet (500 m), 3280+ feet (1000 m), 4920+ feet (1500 m) and 6560+ feet (2000 m) levels.

The shape of the contours and the width between them indicates the form of the land and the gradient. The closer the contour lines (i.e. the narrower the colour bands) are to each other, the steeper the gradient.

Recommended VFR Charts – WAC Chart Elevations

The WAC chart utilises relief shading of elevated ranges and ridges so that they are more evident.

Spot elevations are also shown and the highest spot elevation within each chart graticule is recorded in a bolder lettering than other spot elevations. The graticule on the WACs and VNCs is spaced at 30 minutes of latitude and 30 minutes of longitude.

The contours on VTCs are at 500+, 1000+, 2000+, 3000+, 4000+ and 5000+ feet amsl, but in addition all areas are shaded purple where there is less than 500 feet of clearance between the terrain and the lower limit of the overlying controlled airspace. Like WAC and VNC, the highest spot elevation within each chart graticule is shown in a bolder type than other spot elevations.

Recommended VFR Charts – WAC Chart Details

The VTCs generally cover an area within a 40–50 nm radius from the major airport and are the essential chart for visual navigation within that area. 

Vegetation is usually not shown on WACs, nor are many structures except for towers and similar obstructions to low-flying aircraft; although grain silos — which are an excellent navigation aid usually associated with a railroad — are shown. Railroads, power transmission lines and some roads are depicted.

Wind Data

For all wind velocities, given in meteorological forecasts and actuals, the directions are relative to true north, except if you happen to hear a broadcast from a CTR tower controller (or an Automatic Terminal Information System [ATIS] broadcast). These systems provide the wind direction as magnetic, because the airfield runway numbers are relative to magnetic north. The air route directions shown on ERC-L are also relative to magnetic north.

Universal Time

Time is important for aerial navigation.

The reference time is Universal Coordinated Time (symbol) rather than local time.

The suffix ‘Z’ is used to identify dates and times as UTC, so it may be referred to as ‘Zulu’ time — the phonetic for ‘Z’.

UTC and the 24-hour clock system — rather than local time — are used throughout the aviation information, communication and meteorological services.

(UTC is 10 hours behind Australian Eastern Standard Time – Add an additional hour in a daylight saving time period).

Understanding Charts

LatitudePosition between equator and pole in Northern or Southern HemisphereS 28o 02’
LongitudePosition between prime meridian (Greenwich, England) and anti-meridian in Eastern or Western HemisphereE 151o 59’
Chart latitude and longitude, where: 1o = 60’ (1 degree = 60 minutes).
  • Distance measurement – horizontal (nautical miles – nm)
    • Scale: 1’ of latitude = 1 nm
  • Distance measurement – vertical (feet – ft)
    • Elevations and Altitudes are AMSL

Controlled Airspace & Reading Charts

Controlled Airspace

Airspace of defined dimensions within which air traffic control services are provided. There are two primary definitions of these types of airspace:

  • Control Zones (CTR)
  • Control Area (CTA)

Control Zone

A Control Zone (CTR) is:

  • Controlled airspace extending upwards from the surface of the earth to the specified upper limit.
  • Surround controlled airports (civil & military).
  • Are active during the hours of control tower operation at the airport as published in ERSA or as varied by NOTAM.
  • Outside tower hours, when the CTR is not active, the airspace is reclassified Class G (i.e. outside controlled airspace).
Example of different CTRs on an aeronautical chart.

Control Area

A Control Area (CTA) is:

  • Controlled airspace extending upwards from a specified limit above the earth (e.g. D LL 1000)
  • Designated Class A, D, C or E
  • Normally operate continuously
  • NOTAM or AIP SUP can create, activate or amend CTA to meet temporary requirements
Example of CTA on an aeronautical chart.

Keeping Outside of CTA

Hypsometric Tint highest elevation (AMSL)

+

400 ft max UAV operating height (AGL)

=

Altitude of operations (AMSL)

How to calculate maximum AMSL for UAV operations to avoid CTA.
Calculating highest local terrain altitude (source: Robson, D. (2009). Command Instrument Rating. Cheltenham, AUS: Aviation Theory Centre Pty Ltd.)

Is this < or > CTA LL in the area?
Exercise:  PSN   S 27o 26’  E 152o 57.5’  (in vicinity of Enoggera)

Airspace Classification

Australian Airspace Policy Statement 2015

This Statement is the Australian Airspace Policy Statement 2015.

Section 4:
The AAPS is made pursuant to Part 2 of the Airspace Act 2007. The AAPS provides guidance to the Civil Aviation Safety Authority (CASA), as the airspace regulator, on the administration of airspace as a national resource. The AAPS is also intended to provide guidance for the aviation industry and other aviation agencies

Section 9:
Airspace administration in Australia is generally aligned with the International Civil Aviation Organization (ICAO) prescribed airspace classes and associated levels of service as set out in Annex 11 to the Convention on International Civil Aviation (1944) (Chicago Convention). Differences to the ICAO classes of airspace in Australia are notified to ICAO and listed in the Australian Aeronautical Information Publication (AIP).

Purpose of the AAPS (2015)

Airspace Classes Used in Australian-Administered Airspace

classification of airspace
Australian airspace Architecture (source: https://www.airservicesaustralia.com/services/how-air-traffic-control-works/how-airspace-is-managed/; accessed August 2020)
  • Class A:
    • IFR (instrument flight rules) flights only are permitted. All flights are provided with an Air Traffic Control (ATC) service and are separated from each other.
  • Class B:
    • IFR and VFR (visual flight rules) flights are permitted.
    • All flights are provided with ATC service and are separated from each other.
    • This class is not used at present in Australian-administered airspace.
  • Class C:
    • IFR and VFR flights are permitted.
    • IFR flights are provided with an ATC service and are separated from both IFR and VFR flights.
    • VFR flights are provided with an ATC service for separation from IFR flights and traffic information on other VFR flights.
  • Class D:
    • IFR and VFR flights are permitted and all flights are provided with an ATC service.
    • IFR flights are separated from other IFR flights and are provided with traffic information on all VFR flights.
    • VFR flights are provided with traffic information.
  • Class E:
    • IFR and VFR flights are permitted.
    • IFR flights are provided with an ATC service and are separated from other IFR flights and receive traffic information on VFR flights as far as is practicable.
    • VFR flights are provided with a flight information service, which includes traffic information, as far as is practicable.
  • Class E:
    • IFR and VFR flights are permitted.
    • All participating IFR flights receive an air traffic advisory service and all flights receive a flight information service if requested.
    • This class is not used at present in Australian-administered airspace.
  • Class G:
    • IFR and VFR flights are permitted and do not require an airways clearance.
    • IFR flights must communicate with air traffic control and receive traffic information on other IFR flights and a flight information service.
    • VFR flights receive a flight information service if requested:
      • North of 65°S this flight information service includes directed traffic information to IFR flights on other IFR flights and known VFR flights.

Prohibited, Restricted and Danger Areas

Australia has adopted the ICAO designations described in Annex 15, Chapter 2, of the Chicago Convention for accommodating activities that may be incompatible with routine flying operations, i.e. Prohibited, Restricted and Danger Areas.

These areas and the circumstances in which they can be declared are described at Regulation 6 of the Airspace Regulations 2007. This is consistent with the relevant ICAO documentation.

  • Prohibited Areas (P):
    • An airspace of defined dimensions within which the flight of aircraft is prohibited.
    • CASA must not declare airspace to be a Prohibited Area unless, in the opinion of CASA, it is necessary for reasons of military necessity to prohibit the flight of aircraft over the area.
  • Restricted Areas (R):
    • An airspace of defined dimensions within which the flight of aircraft is restricted in accordance with certain specified conditions.
    • CASR 101.065
    • CASA must not declare airspace to be a Restricted Area unless, in the opinion of CASA, it is necessary in the interests of public safety, including:
      • The safety of aircraft in flight
      • The protection of the environment or security
      • To restrict the flight of aircraft over the area to aircraft flown in accordance with specified conditions.
    • Examples include:
      • Bushfires
      • Major crime scenes
      • Large public events
  • Danger Areas (D):
    • An airspace of defined dimensions within which activities dangerous to the flight of aircraft may exist at specified times.
    • CASA must not declare airspace to be a Danger Area unless, in the opinion of CASA, there exists within or over the area an activity that is a potential danger to aircraft flying over the area.
ERSA entry R633A; NOTAM R663A (source: Airservices Australia. (2013). Visual Terminal Chart Gold Coast.).
ERSA entry R620A; NOTAM R620A or group AMX (Group AMX will also give CTR details) (source: Airservices Australia. (2013). Visual Navigation Chart Brisbane.).

Up-To-Date Information

Notice to Airmen

A Notice to Airmen (NOTAM) is a notice distributed by means of telecommunications containing information concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to personnel concerned with flight operations.

Area Briefing:

  • Aerodrome NOTAM.
  • Prohibited, Restricted, Danger Area NOTAM (individual & group).
  • Flight Information Region (FIR) NOTAM.
  • Head Office NOTAM.

Airservices provide a free registration to access NOTAMs: https://www.airservicesaustralia.com/naips/Account/Logon

Example NOTAM for RAAF Base Amberley (YAMB)

                                NOTAM INFORMATION
                                -----------------

AMBERLEY (YAMB)
                                                                   B432/20
    CTR ACT
    TIMES MAY VARY AT SHORT NOTICE. PILOTS RESPONSIBILITY TO CK AND MNT
    STS AND OBTAIN BRIEFINGS FOR AMX, AEX, AWX AND EVX.
    SFC TO 8500FT AMSL
    FROM 08 052140 TO 08 061300

                                                                   C312/20
    TWY J NOT AVBL
    DUE PARKED ACFT
    FROM 08 060400 TO 08 061200

                                                   C311/20 REVIEW C300/20
    RWY 15/33 NOT AVBL DUE WIP
    MEN AND EQPT WILL VACATE WITH 30MIN PN. CTC WORKS SAFETY OFFICER CS
    'CABLE PARTY' ON COMMON TFC ADVISORY FREQ (CTAF) 118.3 OR
    TEL: 0418 446 459
    FROM 08 051000 TO 08 081830
       2008051000 TO 2008051830
       2008061000 TO 2008061830
       2008071000 TO 2008071830
       2008081000 TO 2008081830

                                                   C290/20 REVIEW C232/20
    AIR MOVEMENT SECTION (AMS) MIL FREQ 361.6 
    DEGRADED SERVICE - RECEIVE ONLY
    FROM 07 150344 TO 10 150200 EST

                                                                   B280/20
    FLIGHT PROCEDURES AMD
    DELETE PARAGRAPH 1.
    AMD EN ROUTE SUPPLEMENT AUSTRALIA (ERSA) 
    FROM 05 072336 TO PERM

                                                   C279/20 REVIEW C135/20
    AUSTRALIAN DEFENCE FORCE FLT INFO PUBLICATIONS AMD
    TERMINAL AUSTRALIA (TERMA), FACILITIES AND PROCEDURES AIR COMBAT
    GROUP NORTH (FAP ACG NORTH)
    ILS-Y RWY 15
    LOC-Y RWY 15
    TACAN RWY 15
    TACAN RWY 33
    RNAV (GNSS) RWY 04
    RNAV (GNSS) RWY 15
    RNAV (GNSS) RWY 33
    CIRCLING MINIMA CAT A 830 (739) -2000 
    DUE CRANE OPS PUBLISHED BY SEPARATE NOTAM. MIL USE ONLY
    FROM 07 082030 TO 10 010830 EST
    DAILY 2030/0830

                                                   C278/20 REVIEW C131/20
    OBST CRANE 427FT AMSL 
    BRG 118 MAG 2.02NM FM ARP
    INFRINGES INNER HORIZONTAL SFC BY 197FT
    FROM 07 082030 TO 10 010830 EST
    DAILY 2030/0830

                                                   C267/20 REVIEW C266/20
    TWY B NOT AVBL
    TWY H NOT AVBL
    FROM 06 290500 TO 08 310500 EST

                                                                   C216/20
    RADIO NAVIGATION AND LANDING AIDS AMD
    TACAN 'AMB' 108.1/CH18X 273829.4S 1524258.0E
    AMD EN ROUTE SUPPLEMENT AUSTRALIA
    FROM 05 260549 TO PERM

                                                                   C215/20
    AMEND ALL TACAN NAV CHECK BOARDS: AMB TACAN OPERATIONAL CHANNEL IS
    18X 
    AZIMUTH & DISTANCE DATA CORRECTIONS: 
    TWY B THR RWY04: 225 DEG 0.5NM 
    TWY A1 THR RWY33: 177 DEG 0.4NM
    TWY C THR RWY33: 148 DEG 0.3NM 
    TWY C THR RWY22: 036 DEG 0.4NM 
    TWY D THR RWY22: 016 DEG 0.4NM
    TWY A4 THR RWY15: 318 DEG 1.3NM  
    AZM & DISTANCE DATA TAKEN AT HOLD POINT EXC FOR TWY A4 TAKEN AT TACAN
    MARKING
    FROM 05 260538 TO 08 260700 EST

                                                   C212/20 REVIEW C189/20
    RADIO NAVIGATION AND LANDING AIDS AMD
    ADD NOTE ASSOCIATED WITH TACAN 'AMB' 108.1/18X
    POSSIBLE BEARING UNLOCKS OUTSIDE 20TAC IN SECTOR R100-R120 DUE
    TERRAIN.
    AMD EN ROUTE SUPPLEMENT AUSTRALIA (ERSA)
    FROM 05 260517 TO PERM

                                                                   C211/20
    AUSTRALIAN DEFENCE FORCE FLT INFO PUBLICATIONS AMD
    TERMINAL AUSTRALIA (TERMA), FACILITIES AND PROCEDURES AIR COMBAT
    GROUP NORTH (FAP ACG NORTH)
    NAVIGATION AIDS 
    AMD ALL REFERENCE TO TACAN 'AMB':
    108.1/CH18X 273829.4S 1524258.0E
    FROM 05 260510 TO PERM

Aeronautical Information Publication Supplements & Information Circulars

Aeronautical Information PublicationAIPA publication issued by or with the authority of a State and containing aeronautical information of a lasting character essential to air navigation.
AIP Supplement Military Exercises!AIP SUPTemporary changes to the information contained in the AIP which are published by means of special pages.
Aeronautical Information CircularAICA notice containing information that does not qualify for the origination of a NOTAM, or for inclusion in the AIP, but which relates to flight safety, air navigation, technical, administrative or legislative matters.
Summary of aeronautical publication and information packages.

Airservices provide a free access these publications and information packages:

Example of AIC information packages.

Privacy

Privacy from aeronautical operations:

  • Governed by local, state, and federal law
  • Any tasking must be lawfully commissioned.
  • Only data related to the tasking should be collected.

It is your responsibility to ensure any other data collected (which is not related to the tasking) is securely stored or disposed of so as to not end up in the public domain.

Part 1 – Legislation for Unmanned Operations

Aim

To gain an understanding of the legislation relevant to operating unmanned aircraft within Australia.

Objectives

At the end of this briefing you will be able to:

  • Have a basic understanding of key legislation towards the operation of unmanned aircraft in Australia.
  • The responsibilities placed on the pilot when operating within Australia.

General Unmanned Operations

Part 101 Amendments
for Remotely Piloted Aircraft

CASA is pleased to announce amendments to Part 101 came into effect on 29 September 2016.

These amendments reduce the cost and legal requirements for lower-risk remotely piloted aircraft (RPA) operations. More complex operational matters will be dealt with in a new manual of standards to be developed with industry, providing greater flexibility and responsiveness in this rapidly evolving area.

This regulation updates terminology to align with the International Civil Aviation Organization. In particular, the term UAV (unmanned aerial vehicle) now becomes RPA (remotely piloted aircraft). Over time, CASA forms and processes will reflect these changes.

The amendments to Part 101 create new weight classifications for RPA:

  • Very small (100g<2kg).
  • Small (2-25kg) (where required with 7kg restriction).
  • Medium (25-150kg).
  • Large (>150kg).

Standard RPA
Operating Conditions

  • You must only fly during the day and keep your RPA within visual line-of sight.
  • You must not fly your RPA higher than 120 metres (400ft) AGL.
  • You must keep your RPA at least 30 metres away from other people.
  • You must keep your RPA at least 5.5km away from controlled aerodromes.
  • You must not fly your RPA over any populous areas. These can include: beaches, parks and sporting ovals.
  • You must not fly your RPA over or near an area affecting public safety or where emergency operations are underway (without prior approval).
    • This could include situations such as a car crash, police operations, a fire and associated firefighting efforts and search and rescue.
  • You can only fly one RPA at a time.

You must not fly your RPA autonomously under the amendments. CASA is still developing suitable regulations for autonomous flight; however, there is scope for CASA to approve autonomous flight on a case-by-case basis.

Taken from the CASA web site: https://www.casa.gov.au/aircraft/standard-page/part-101-amendments-cutting-red-tape-remotely-piloted-aircraft

Definition of a Model Aircraft

5.1  A model aircraft is any unmanned aircraft, other than a balloon or kite, which is flown for sport or recreational purposes, weighing not more than 150 kg including fuel and equipment installed in or attached to the aircraft at the commencement of its flight.

5.2  A model aircraft flown for any other purpose is covered by the term ‘Unmanned Aerial Vehicle’ (UAV) and is subject to the rules applicable to UAVs.

AC 101-3(0)  JULY 2002

Commercial Activities

9.1 Definition

9.1.1 A model aircraft flight is considered to be commercial if it is conducted for any purpose other than the sport of flying the model or learning or teaching the sport. It is commercial if it is used as the tool for conducting any other commercial purpose such as aerial photography, etc.

9.1.2 In simple terms, if you receive financial benefit for the service provided by your model aircraft (other than teaching the sport), you have been conducting a commercial activity.

AC 101-3(0) JULY 2002 (Model Aircraft)

Advisory Circular

UAV Controller Certificate

CASR 101.295:

  • Issued by CASA to an individual piloting/flying/controlling a UAV.
  • Must be produced to a CASA Flying Operations Inspector on demand.

Instrument EX58/13 training:

  • Less than 400ft AGL.
  • Visual line of sight.
  • Outside controlled airspace.
  • More than 3nm from an aerodrome or aircraft landing area.
  • Not over a populous area (defined in CASR 101.025).
  • Not within 30m of a person other than operator’s personnel.

Permitted type of aircraft:

  • Electric power plant
  • Fixed wing
  • Multirotor or powered lift

Operators Certification Duration

101.350 – How long operator’s certification remains in force:

  • An operator’s certification remains in force until it is cancelled.
  • However, an operator’s certification is not in force during any period of suspension.

101.355 – Certification not transferable:

  • Certification as a UAV operator is not transferable.

Civil Aviation Safety Regulations 1998

100 ft separation between UAVs and aircraft containing people.

Where Can I Find Information?

Hours of Operation (As nominated in ERSA)

Hours of operation are shown in UTC unless otherwise stated:

NAIPS

General Met Forecasts

Special MET Briefing

Sample Area Forecast

Sample AFOR Briefing

ARFOR

  • Refer to the PCA for area designations.
  • The Area Forecast system is designed primarily to meet the needs of general aviation pilots. The system provides for the routine issue of forecasts for designated areas and the prompt issue of amendments when prescribed criteria are satisfied. Forecasts are issued for the numbered areas shown on the PCA.

Aerodrome Weather Information Service (AWIS)

  • Free Call
  • Examples from ERSA:
    • Archerfield (07) 3239 8720
    • Amberley (07) 5361 3581

Vertical Navigation

Pressure distribution with altitude.
  • The mass of the atmosphere decreases with height
  • Atmospheric pressure (weight of atmosphere above a datum) measured in hectopascals (hpa) by a barometer
  • Pressure decreases with height
    • 1 hpa every 30 feet (near sea level)
    • 1 hpa every 50 feet (near 16,000 ft)

Vertical Navigation

Altimeter – device for measuring vertical distance (in feet) above a pre-defined datum

In the absence of a terrain database, set QFE (airfield ambient pressure) as datum. Main Scale will then read height AGL.

Standard height terms (source: http://www.griffin-helicopters.co.uk/note/altimeter.htm accessed 24 Feb 2014)

AC 101-1(0) Unmanned aircraft and rockets (July 2002)

6.5 Rules of Operations

6.5.1 UAV flights over populous areas may not be conducted except:
(a) by a UAV certificated for such flight; and
(b) in accordance with conditions specified in an approval issued by CASA; or
(c) at an altitude which would allow the UAV to clear the area in the event of engine failure.

AC 101-1(0) Unmanned aircraft and rockets (July 2002)
SectionTitleRequirement
101.055Hazardous OperationA person must not operate an unmanned aircraft in a way that creates a hazard to another aircraft, another person, or property
101.065Operation in prohibited or restricted areasA person may operate an unmanned aircraft in or over a prohibited area, or in or over a restricted area, only with the permission of, and in accordance with any conditions imposed by, the authority controlling the area
101.090Dropping or discharging thingsA person must not cause a thing to be dropped or discharged from an unmanned aircraft in a way that creates a hazard to another aircraft, a person or property
101.095Weather and day limitationsA person may operate an unmanned aircraft in or into cloud, or at night, or in conditions other than VMC, only if permitted by another provision of this Part or in accordance with an air traffic control direction. VMC (ops < 1000ft AGL) = clear of cloud, flight visibility 5000m
101.015Application of registration and marking requirementsPart 45 and 47 do not apply to an aircraft (other than a large UAV) to
which this Part applies, nor to a micro UAV.
Note: A large UAV is required to carry a manufacturer’s data plate and an aircraft registration identification plate — see respectively regulation 21.820 and Subpart
45.D.

Hazard or Threat?

Hazards and threats are essentially different states of the same thing!

A hazard is effectively the source in a harmless state. This could be for example a river close to your location.

A threat is the source in a harmful state. The river is now in flood, and the flood has reached your location.

UAS operator’s certificate (OC) CASR 101.270

Needed by the legal entity (i.e. sole trader, company etc.) that is carrying on the business of UAV operation.

Issued by CASA under CASR 11.056 specifying:

  • Certification of entity as an operator of UAV.
  • Conditions of certification (general and operations specific).
  • Authorised UAVs and types of operation.
  • Requirement for Operations Manual.
  • Names of key personnel that must be employed by the entity.
  • Flight profile limitations.

Part 1 – Human Factors in Unmanned Operations

Aim

To gain an understanding of the impacts of human factors, the relation of these to unmanned operations, and the associated safety precautions.

Objectives

At the end of this briefing you will be able to:

  • Define the terms threat, error, undesired aircraft state and countermeasure.
  • Identify potential threats and errors applicable to UAV operations and propose appropriate countermeasures.
  • State personal safety precautions to be taken when engaged in UAV operations.

Threats & Errors

What is a Human Factor?

What: Application of scientific knowledge (mostly from the human sciences of psychology, anthropology, physiology and medicine) to the design, construction, operation, management and maintenance of products and systems.

Why: To reduce the likelihood of human error and therefore the likelihood of negative outcomes while operating or using products or systems.

How Accidents Occur

Defenses in depth model (source: Reason, 1997)

Key points to note:

  • Multiple defenses / layers of failure:
    • Orgsanisational.
    • Supervisory.
    • Personnel and operating environment.
    • Rules and procedures.
  • Downward gradient:
    • Each layer is sequential – failures at the top compromise defenses below.
    • The pilot (you) could be the last line of defense.

Threat & Error Management

Threat:

  • Occurs outside the influence of the crew.
  • Increases operational complexity of a flight.
  • Requires crew attention and management to maintain safety margins.
  • Example: change of wind direction likely during duration of mission.

Error:

  • Crew action or inaction that leads to a deviation from crew or organisational intentions or expectations.
  • Reduces safety margins.
  • Increases probability of adverse operational events.
  • Example: operating crew does not check wind direction before setting the landing rally.

Undesired Aircraft State:

  • Position, speed, altitude or configuration of an aircraft that results from crew error.
  • Clearly reduces safety margins.
  • Example: UAV approaches with a tailwind, overshoots and crashes into a fence.

Refer to reference material (Defensive Flying for Pilots: An Introduction to Threat and Error Management) for full document. Accessed 18 Sep 2013: http://homepage.psy.utexas.edu/homepage/group/helmreichlab/publications/pubfiles/TEM.Paper.12.6.06.pdf

Countermeasures

ThreatCountermeasure
Conflict / breakdown of separation between UAV and transiting traffic– Lookout – multi-pilot crew
– Listen out
– Communicate
– NOTAMs
Personnel other than those of the operator coming within 30 m– Lookout – multi-pilot crew
-Signs
– Physical barriers
Airframe / component failure-Design & Testing Program
– Maintenance program
– Pre-flight checks
– Post flight checks
UAV launched with insufficient battery voltage– Pre-flight checklist includes battery voltage test
Pilot functioning adversely affected by fatigue, hunger or dehydration– Appropriate rest before mission
– Suitable area to take breaks
– Bring sufficient food and water for extended deployment
Pilot functioning adversely affected by alcohol or drugs– Minimum 8 hours between alcohol consumption and flying
– Sufficient time between consumption and flying to be free of effects of alcohol / drugs
– Check medications with DAME
Example breakdown of threats and potential countermeasures.

Human Operators

Situational Awareness

  • Perception of the current environment
  • Interpretation of the immediate situation
  • Anticipation of what will happen next

Perception

Use all available senses (sight, hearing, smell, feel etc):

  • Direct observation of vehicle
  • Direct observation of terrain
  • Direct observation of airspace / traffic (lookout)
  • GCS data
  • Radio
  • NOTAMs / weather

Interpretation

Converting perception into reality!

Perception illusion #1 (source: http://serendip.brynmawr.edu/exchange/courses/jamesfamily/s10/archive/10 accessed 19 Sep 2013)
Perception illusion #2 (source: http://www.rit.edu/cla/gssp400/muller/muller.html accessed 19 Sep 2013)
Perception illusion #3 (source: http://stephenlaw.blogspot.com.au/2013/03/tricks-of-mind-march-30th.html accessed 19 Sep 2013)

Hazardous Attitudes

AttitudeBehavioural Marker
Anti-AuthorityRefusal to listen to advice Contempt for the rules
DeferenceWhatever goes wrong is someone else’s fault Defers to opinion of others above using own initiative
ImpulsivenessCommits to action without considering consequences Acting on the spur of the moment
Invulnerability‘It will never happen to me’ syndrome
Macho‘There’s nothing I can’t do and there’s nothing I won’t try’
ResignationUnwillingness to take control of a situation Giving up

Vision

Cross-section of a human eye (source: http://www.rugusavay.com/structure-of-eyes-and-their-functions/ accessed 19 Sep 2013)
  • Light enters through pupil.
  • Ciliary muscles shape the lens.
  • Image (upside-down) projected onto retina (part of the brain connected by the optic nerve) to interpretation.

Refractive Errors

Common types of vision issues:

  • Hyperopia (farsightedness)
    • Distant objects clear
    • Near objects blurry
    • Convex lens to correct
  • Myopia (nearsightedness)
    • Distant objects blurry
    • Near objects clear
    • Concave lens to correct
  • Astigmatism
    • Distortion of the image
    • Different parts unequally focused
    • Cylindrical lens to correct

Blind Spot

A “blind spot” occurs when image focused on the retina falls across the optic nerve.

Humans always have a blind spot, but our brains learn to ignore it. This can be very dangerous if we’re not aware!

Exercise:

  • Draw circle with cross in it on left side of paper.
  • Draw square on right side of paper.
  • Cover left eye.
  • Hold paper at arm’s length.
  • With right eye, look at the circle.
  • Move the paper closer to you while focusing on circle.
  • Square will disappear when image falls on optic nerve.

Safety during Outdoor Operations

The sun.
  • Don’t look directly at the sun
  • Personal Protective Equipment (PPE):
    • Hat
    • Sunglasses
    • Sunscreen
    • Long-sleeved shirt

Real-World Operations

Crew Coordination

 Basic principles of crew coordination:

  • Verbal and non-verbal communication factors
  • Barriers to communication
  • Listening skills
  • Assertion skills
  • Factors affecting decision-making processes
  • Communication:
    • Attitude
    • Personality
    • Judgement
    • Leadership style
  • Leadership
  • Qualities
  • Poor crew coordination
  • Other human factors

Effective Communication Techniques

Effects of stress on personal performance, ways of managing, and controlling stressors:

  • Concepts of fatigue
  • Environmental stress symptoms, causes and effects
  • Ergonomics of control systems and instruments
  • Principles of stress management
  • Short- and long-term stressor effects on performance
  • Stress and arousal interaction

Operational Considerations

  • Error management, including:
    • Error types.
    • Causes.
    • Consequences.
  • Human factors that may influence personal performance during RPAS operations.
  • Human performance and limitations, including:
    • The senses
    • Memory
    • Situational Awareness
  • In a “defense context“:
    • Relevant defense orders.
    • Commanded instructions.
  • Relevant Work Health & Safety (WHS), Occupational Health & Safety (OHS), and other procedures and regulations.

Regulations & Orders

Relevant Sections of Civil Aviation Safety Regulations (CASRs) and Civil Aviation Orders:

  • Human factors limitations.
  • Physical examination requirements.
  • Medical clearances.

Requirements for reporting and documenting safety incidents and safety critical errors that may have occurred during an RPAS Mission:

  • RPAS flight instruments visual scanning techniques
  • Undesired RPAS states:
    • Incorrect RPAS configuration associated with a reduced margin of safety.
    • Inappropriate RPAS flight mode awareness and selection.
    • Misapplication of flight controls.
    • RPAS pilot induced aircraft position.
    • RPAS pilot induced speed deviation.

Part 1 – Aircraft Radio Operation

Aim

To gain a basic understanding of the requirements and use of aircraft radio and its operation in the field of aviation.

Objectives

At the end of this briefing you will be able to:

  • State the authorisation granted by, and operating condition associated with, the aeronautical radio operator certificate
  • Make a properly formatted broadcast appropriate to RPAS operations

Aircraft Radio

The Function of Aircraft Radio

When using in the context of aviation, it is sometimes called “aircraft radio” or “air-band radio“.

The use of a radio does not guarantee that all your communication problems will be resolved. A radio is a tool that we can choose to use, but we need to understand it’s limitations!

In electing to use a radio we assume:

  • That the other aircraft/person actually has an appropriate radio.
  • That all radios are working as expected.
  • That the other radio is turned on.
  • That the other radio is tuned to the same frequency.
  • That the other radio has been set to a volume that can be heard.
  • That the person monitoring the radio is actually listening to the radio.
  • That what you intended the message to mean is what the other person understood the message to mean!

All of these things things to all be in place at the same time!

Definite “Show-Stopper” or Combination of Errors?

If the radio is turned off, or the ‘wrong’ frequency selected – this is a show-stopper!

More subtly, although it seems like the correct action is being taken, a combination of events may lead to disaster!

“Swiss Cheese” model (source: James Reason’s “Managing the Risks of Organizational Accidents”).

Aircraft Radio as a Threat & Error Countermeasure

Radio creates an opportunity for you to:

  • Develop & maintain your situational awareness
  • Identify and (possibly) manage threats
  • Possibly communicate with potential threats and de-conflict

Aviation Task Prioritisation

Task prioritisation, also referred to as “Applied Risk Management”, consists of four primary tasks:

  • Aviate
  • Navigate
  • Communicate
  • Administrate

Radiotelephony

The Phonetic Alphabet

LetterWordAnnunciationLetterWordAnnunciation
AALFAAL farNNOVEMBERNo VEM ber
BBRAVOBRAH vohOOSCAROSS cah
CCHARLIECHAR leePPAPApah PAH
DDELTADELL tahQQUEBECKeh BECK
EECHOECK hoRROMEOROW me oh
FFOXTROTFOKS trotSSIERRASee AIR rah
GGOLFGOLFTTANGOTANG go
HHOTELhoh TELLUUNIFORMYOU nee form
IINDIAIN dee AVVICTORVIK tah
JJULIETTJEW lee ETTWWHISKYWISS key
KKILOKEY lohXX-RAYECKS ray
LLIMALEE mahYYANKEEYANG key
MMIKEMIKEZZULUZOO loo
Annunciation of the Phonetic Alphabet.

Numbers

All numbers shall be transmitted by pronouncing each digit separately (e.g. 10 is WUN ZE-RO, 236 is TOO THREE SIX), except for:

  • Whole hundreds
    • 500 is FIFE HUN-dred
  • Whole thousands
    • 7,000 is SEV-en TOU-SAND
  • Combinations of thousands and whole hundreds
    • 7,500 is SEV-en TOU-SAND FIFE  HUN-dred

Note: The meteorological way of expressing cloud cover is in eighths of the sky covered:

  • Eighths in radio transmissions is expressed as “okta’s“.
  • A little over half the sky covered, say 5/8, would be expressed as:
    • FIFE-oktas
NumberAnnunciation
50FIFE ZE-RO
85AlT FIFE
612SIX WUN TOO
900NIN-er HUN-dred (whole hundreds only)
3,000TREE TOU-SAND (whole thouands only)
3,500TREE TOU-SAND FIFE HUN-dred
12,000WUN TOO TOU-SAND
12,700WUN TOO TOU-SAND SEV-en HUN-dred
12,755WUN TOO SEV-en FIFE FIFE
Annunciation of the numbers.

Standard Words & Phrases

Word/Phrase  Meaning

  • ACKNOWLEDGE: Let me know that you have received and understood this message.
  • AFFIRM: Yes.
  • APPROVED: Permission for proposed action granted.
  • BREAK: I hereby indicate the separation between portions of the message.
    • To be used where there is no clear distinction between the text and other portions of the message.
  • BREAK BREAK: I hereby indicate separation between messages transmitted to different aircraft in a very busy environment.
  • CANCEL: Annul the previously transmitted clearance.
  • CHECK: Examine a system or procedure.
    • No answer is normally expected.
  • CLEARED: Authorised to proceed under the conditions specified.
  • CONFIRM: Used in the context of “Have I correctly received the following … ?” or “Did you correctly receive this message?”.
  • CONTACT: Establish radio contact with.
  • CORRECT: That is correct.
  • CORRECTION: An error has been made or the message indicated the wrong information in this transmission, followed by the correct version “[wrong information] CORRECTION [correct information…]”.
  • DISREGARD: Consider that transmission as not sent.
  • HOW DO YOU: What is the readability of my transmission?
  • I SAY AGAIN: I repeat for clarity or emphasis.
  • MONITOR: Listen out on: [frequency].
  • NEGATIVE: “No”, “Permission is not granted”, or “That is not correct”.
  • OVER: My transmission is ended and I expect a response from you
    • Not normally used in VHF communication
  • OUT: My transmission is ended and I expect no response from you
    • Not normally used in VHF communication
  • READ: The readability is:Unreadable
    • Readable now and then
    • Readable but with difficulty
    • Readable
    • Perfectly readable
  • READ BACK: Repeat all, or the specified part a’ this message back to me exactly as received
  • RE-CLEARED: A change has been made to your last clearance and this new clearance supersedes your previous clearance or part thereof.
  • REPORT: Pass ore the following information
  • REQUEST: I should like! to know or I wish to obtain
  • ROGER: I have received all of your last transmission, [Under NO circumstances to be used in reply to a question requiring read back or a direct answer in the affirmative or negative]
  • SAY AGAIN: Repeat all or the following part at your last transmission
  • SPEAK SLOWER: Reduce your rate of speech.
  • STANDBY: Wait and I will call you.
  • VERIFY: Check and confirm with originator.
  • WILCO: I understand your message and will comply with it.
  • WORDS TWICE: Can mean:
    • As a request: Communication is difficult: “Please send every word or group of words twice.”
    • As information: Since communication is difficult, every word or group of words in this message will be sent twice.

Radio Certification & Standard Calls

Aeronautical Radio Operator Certificate

Aeronautical Radio Operator Certificate (AROC) is specifically the Authorisation & Condition (CASR 64.035).

Why do we need it and what does an AROC allow us to do?

  • It will allow us to transmit on a frequency of a kind used for the purpose of ensuring the safety of air navigation.
  • You may only make a transmission if you are the holder of a current a current aviation English language proficiency assessment!

Operator Conduct

AuthorityResponsibilities
Radiocommunications Act 1992
International Radio Regulations (published by International Telecommunications Union)		Maintain secrecy:
Must preserve secrecy of communications to which the operator may become acquainted
Unauthorised transmissions:
– Interference
– False of deceptive messages
– Bad language
– Unnecessary conversations
– Harassing, alarming or affronting behaviour
– Using radio as an explosives trigger
Summary of the rosponsibilities imposed by the Radiocommunications Act 1992.

Brevity and Clarity

Remember: when you make a transmission you are saying something for someone else to hear, and hopefully understand what you meant!

Some points (and common issues):

  • Speak clearly.
  • Position the microphone (know your equipment).
  • Remember transmitter latency (press, pause-2-3, speak).
  • Keep a constant volume – no need to yell (or swallow the mic).
  • Keep an even rate of speech – in the excitement don’t speak quickly.
  • Choose your words. Send enough to communicate, but do not flood the airwaves!

Paraphrasing George Bernard Shaw: The greatest fallacy with communication is that there was!

Declaring an Emergency

There are three types of emergency, and the pilot must preface his call with the appropriate words:

  • MAYDAY: (repeated three times) for a distress call.
  • PAN-PAN: (repeated three times for an urgency call.
  • SECURITY: (repeated three times) for a safety call.

Distress Call (MAYDAY)

The MAYDAY call is derived from “m’aidez” – “help me”.

This is the absolute top priority call. It has priority over all others, and the word mayday should force everyone else into immediate radio silence.

Used when you require immediate assistance, and are in grave and immediate danger.

Any aircraft making an emergency radio call is to be given priority over all other aircraft/ground operations.

If a distress call is received radio operators may initiate or impose radio silence on all other stations.

This will be heard as:

  • “STOP transmitting; MAYDAY”
  • “ALL stations; STOP transmitting; MAYDAY”

This process ensures that all communications between the aircraft in distress are received by radio operators and emergency response teams clearly & accurately.

Construction of a MAYDAY Call

The distress message should contain as much of the following information as possible, and if possible in the sequence below:

  • “MAYDAY MAYDAY MAYDAY”
  • [Aircraft callsign] [Aircraft callsign] [Aircraft callsign]
  • [Position and time]
  • [Heading]
  • [Airspeed]
  • [Altitude]
  • [Aircraft type]
  • [Nature of distress]
  • [Captain’s intentions]
  • [Any other information that may facilitate the rescue]

Urgency Call (PAN-PAN)

Panne (pronounced: “pan”) is a breakdown, such as a mechanical failure.

Used when and emergency exists but does not require immediate assistance.

Typical Situations include:

  • If you are experiencing navigational difficulties and require the urgent assistance of traffic services.
  • If you have a passenger on board who is seriously ill and required urgent attention.
  • If you see another airplane or ship the safety of which is threatened and urgent action is perhaps needed.
  • If you are making an emergency change of level in controlled airspace and you may conflict with traffic below.

PAN – A Three-Letter Acronym

As a Three-Letter Acronym (TLA):

  • “Possible assistance needed”
  • “Pay attention now”

The TLA is derived from “pan” and is used in maritime and aeronautical radio communications courses as a mnemonic to radio and communications operators.

Note: it is very important remember the difference between mayday and pan-pan emergency communications.

Construction of a PAN-PAN Call

For an urgency call, the pilot should transmit:

  • PAN-PAN PAN-PAN PAN-PAN
  • [Callsign of a specific station or ‘all stations’]
  • [Aircraft callsign]
  • [Request for bearing, course or position, if required]
  • [Position and time]
  • [Heading]
  • [Airspeed]
  • [Altitude]
  • [Aircraft type]
  • [Available flight time]
  • [Nature of emergency]
  • [Captain’s intentions]

Security Call (SECURITY)

194 specifies that a message known as a safety signal shall be transmitted by an aircraft when considered necessary to advise the existence of a hazard to air navigation or hazardous meteorological conditions.

The specific circumstances for this call:

  • The safety signal shall be transmitted when an aircraft wishes to transmit a message concerning the safety of navigation or to give important meteorological warnings.
  • The safety signal shall be sent before the call and in the case of radiotelegraphy:
    • Shall consist of 3 repetitions of the group TTT (- – -), sent with the letters of each group and the successive groups clearly separated from each other.
    • Shall consist of the word “SECURITY”, repeated 3 times.

The “SECURITY” call may be used when there has been a breach in the security of the aircraft or its crew during flight.

An example of this would be an aggressive or agitated passenger on board who is interfering with the pilot.

Construction of a SECURITY Call

There are very few occasions when it would be necessary to transmit a security call, nevertheless you are required to know of the existence of this type of message in case it should ever become necessary to send one – or should one be received.

  • Pilot:
    • SECURITY SECURITY SECURITY
    • Melbourne Centre
    • Alfa November Kilo
    • One two five decimal nine
    • Severe turbulence and windshear experienced in the easter-lee of Wilson’s Promontory up to three thousand feet
  • Melbourne ATS:
    • Alfa November Kilo
    • Melbourne Centre
    • Copied

Radio Silence

An aircraft in distress or the appropriate ground station may impose radio silence on all other stations in the area or on any particular station causing interference, asking them to stop transmitting.

For example:

  • All stations
  • Stop transmitting
  • MAYDAY

Types of Radio Calls

There are three main types of radio transmissions:

  1. Report:
    • A report is generally made to a specific air traffic services unit.
    • A response is expected.
  2. Broadcast:
    • A broadcast is usually made in the form of a traffic advisory.
    • May be addressed to “all stations“.
    • No response is expected.
  3. Call:
    • A call is made to a specific station.
    • A response is expected.

Clearance and Read-Back

At certain times during a manned flight a clearance must be obtained from an air traffic control unit before proceeding. (e.g. takeoff, landing and taxi.)

If a manned aircraft intends to operate in controlled airspace it must obtain prior clearance.

The following clearances and instructions must be read back:

  • An ATC route clearances in its entirety, and any amendments
  • En route holding instructions.
  • Any route or holding point specified in a taxi clearance.
  • Any clearances and instructions to hold short of, enter, land on, conditional line-up.
  • On, take-off from, cross, taxi or backtrack on, any runway.
  • Any approach clearance.
  • Assigned runway, altimeter settings directed to a specific aircraft, radio and radio navigation aid frequency instructions.
    • Note: an “expectation” of the runway to be used is not to be read back.
  • SSR (secondary surveillance radar) codes, data link logon codes.
  • Level instructions, direction of turn, heading and speed instructions.

A Typical Read-Back Call

A “read back” is to:

  • Confirm receipt of the transmission.
  • Confirm that the pilot has understood the direction (no confusion or misunderstanding).
  • To keep transmissions short, sharp and to the point.

For example:

  • The call received from the tower:
    • Delta Alfa November cleared to land.
  • The pilot should respond:
    • Cleared to land Delta Alfa November.

The pilot has “read back” the direction so as to ensure no confusion. The pilot has also given his call sign to again ensure the intended recipient has received the transmission and is acting on it.

Broadcast Calls

A call we might reasonably be expected to make:

  • A broadcast is a traffic advisory passed to all interested parties on that frequency
  • No response required.
  • Unmanned aircraft must always have the word unmanned before aircraft type.
FormatExample
LocationAmberley
<Location> TrafficAmberley Traffic
Aircraft TypeUnmanned Aircraft
Possibly: small unmanned aircraft
<Callsign>[Unless assigned, we do not have a callsign]
Position and Intentions7 miles north-west, not above 400 AGL, for the next 20 minutes
Examples of broadcast call formats.

Part 2 – Radio Technologies

Aim

To gain a basic understanding of the types of equipment and technologies that enable aircraft radio and its operation in the field of aviation.

Objectives

At the end of this briefing you will be able to:

  • Have a basic understanding of aircraft radio devices.
  • Describe the principles and limitations of VHF and HF radio wave propagation
  • Use aeronautical documents to select VHF radio frequencies for operations in Class G airspace (i.e. outside controlled airspace)

Radio Devices

The Transponder

A transponder (short for transmitter-responder, and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) is an electronic device that produces a response when it receives a radio-frequency interrogation. Secondary Surveillance Radar (SSR) is referred to as “secondary“, to distinguish it from the “primary” radar that works by passively reflecting a radio signal off the skin of the aircraft, and displays them on a screen with a simple blip.

Typical transponder control panel.

Primary radar determines range and bearing to a target with reasonably high fidelity, but it cannot determine target elevation (altitude) reliably except at close range. SSR uses an active transponder (beacon) to transmit a response to an interrogation by a secondary radar. This response most often includes the aircraft’s pressure altitude and a 4-digit octal identifier.

Secondary surveillance radar (SSR) equipment detects the stronger specific transponder signal (called a “squawk“), allowing better identification of your aircraft.

Transponder Operation

Set the transponder to ON or ALT (in this case ALT is ON in Mode “C”).

Activating the transponder will make the aircraft (and altitude if Mode “C”) visible to ATC, and allow air traffic controllers to receive conflict alerts involving your aircraft. Larger aircraft will also be able to receive Airborne Collision Avoidance System (ACAS) advisories.

Make sure you know how to operate the “IDENT” function on your transponder, however do not operate it unless directed to do so by ATC.

Transponder Codes (Manned Aircraft)

If you have not been given a specific code by ATC, set code:

  • Code 1200: Civil VFR flights in class E or G airspace (Australia)
  • Code 3000: Civil flights in classes A, C and D airspace, or IFR flights in Class E airspace (Australia)

Other Allocated Codes within Australia:

  • Code 0100: Flights operating at aerodromes (in lieu of codes 1200, 2000 or 3000 when assigned by ATC or noted in the Enroute Supplement (Australia))
  • Code 2000: Civil IFR flights in Class G airspace (Australia)
  • Code 4000: Civil flights not involved in special operations or SAR, operating in Class G airspace in excess of 15NM offshore (Australia)
  • Code 5000: Aircraft flying on military operations (Australia)
  • Code 6000: Military flights in Class G airspace (Australia)

“Special” Codes:

  • Code 7700: Emergency
  • Code 7600: Radio Failure
  • Code 7500: Aircraft subject to unlawful interference (hijacking)

Emergency Locator Transmitter

Usually fixed in aircraft, ELTs are designed to be activated automatically during a crash, typically by a g-force activated switch or, less commonly, by a water-activated switch. Additionally, ELTs can also be wired into a remote switch on the instrument panel of an aircraft for manual activation by the pilot or a passenger.

An example of an Emergency Locator Transmitter

Once activated, ELTs are required to operate continuously for at least 24 hours. About the size of a 1 litre carton of milk, many ELTs are designed to be portable so that in the event of a crash they can be removed from the aircraft (or wreckage) to a safer location and manually activated if necessary.

Emergency Locator Transmitter Regulation

From 1 February 2009, all Emergency Locator Transmitters (ELTs) must operate on frequencies 406 and 121.5 MHz. ELTs which operate solely on 121.5 and 243 MHz are now obsolete.

The Civil Aviation Regulations 1988 (CAR) require the carriage of an ELT on most flights in Australian airspace.

ELTs are distress beacons which are activated following an accident either automatically by embedded electronics, or manually by a pilot or other person. An active beacon is detected by orbiting satellites which transmit a signal to search and rescue coordinators.

Radio Transmission

Radio Wave Propagation

As the pilot of an unmanned aircraft it is important to have a firm understanding of the mechanism of radio wave propagation.

This understanding will afford you a better understanding of the advantages and limitations of the various modes of transmission, and where communications may not be possible.

As an example, the VHF band is less susceptible to static interference, making them well suited for voice communications – however VHF signals are “line of sight” signals, meaning that they travel in straight lines. The transmitting and receiving antennae must be “visible” to each other, with no obstructions between them.

Wavelength

Mathematically, the wavelength (λ) is defined by the speed with which the wave propagates (c) divided by frequency (f) of the wave.

A depiction of a radio wave.

Wavelength Formula (λ):

λ = c / f 

Speed (c): Considering that our waves propagate in air, we can consider as the speed of light in vacuum: c ≈ 300,000,000 m/s;

Frequency (f): frequency of the signal will be using.

Example of a 900 MHz system:

λ = (300 Mm/s) / (900 MHz) = 0.33333, or 33.33 cm.

Encoding Data into Radio Waves – Amplitude Modulation (AM)

Amplitude modulation of a radio wave.

Encoding Data into Radio Waves – Frequency Modulation (FM)

Frequency modulation of a radio wave.

Encoding Data into Radio Waves – Pulse Modulation (PM)

The aim of pulse modulation methods is to transfer a narrowband analogue signal, (for example a phone call), over a wideband baseband channel or, in some of the schemes, as a bit stream over another digital transmission system.

Pulse modulation of a radio wave.

In terms of what we are looking at , pulse modulation can be something as “simple” as ON/OFF encoding!

In music synthesizers, modulation may be used to synthesise waveforms with an extensive overtone spectrum using a small number of oscillators. In this case the carrier frequency is typically in the same order or much lower than the modulating waveform.

Radio Wave Propagation Paths

The frequency of the radio wave governs the mode of propagation of the radio wave.

Understanding the benefits and disadvantages of the different modes of radio wave propagation allows a better choice of radio system that is better suited to your application.

Groundwaves and Skywaves

A groundwave (or surfacewave) is the part of the signal that travels along the surface of the earth, from the transmitter to the receiver. The strength of the groundwave is inversely proportional to frequency, being strongest at low frequencies. As frequency is increased, the distance covered by the groundwave decreases.

The range of a MW groundwave signal is limited to a 100 or so km during daylight, stations that are geographically separated by 200km or so can operate on the same frequency without causing interference to each other (in theory!).

The skywave is the part of the signal that is sent skywards and is reflected from the troposphere with the spacewave (not a term in common use these days) being the part that is reflected from the ionosphere.

The skywave is now taken to mean any signal other than the groundwave. As the D layer disappears at night, MW signals from the continent and further afield can be heard as they are being propagated by skywave.

Normally skywave signals on MW would not be heard during daylight as the D region would absorb the signals like an RF sponge.

Propagation Modes

Example of a groundwave mode of propagation.

Groundwaves:

  • Follow earths contour
  • Affected by natural and man-made terrain
  • Salt water forms low loss path
  • Several hundred mile range
  • Common use with 2-3 MHz signals
Example of a spacewave mode of propagation.

Skywaves and Spacewaves:

  • Line of Sight (LOS) wave
  • Ground diffraction allows for greater distance
  • Approximate Maximum Distance (D) in miles:
    • D = √(2htx +2hrx)
    • Note: antenna height in feet.
  • No strict signal frequency limitations.
  • Reflected off ionosphere (20-250 miles high)
  • Large ranges possible with single hop or multi-hop
  • Transmit angle affects distance, coverage, refracted energy
Categorisation of wave propagation categories.
Radio wave reflection off of the ionoshpere.

The Ionosphere

The ionosphere is a layer of partially ionized gasses below troposphere:

  • Ionization caused by ultra-violet radiation from the sun
  • It is affected by:
    • Available sunlight
    • Season
    • Weather
    • Terrain
  • Free ions and electrons reflect radiated energy

It consists of several ionized layers with varying ion density. Each layer has a central region of dense ionization.

LayerAltitude (Miles)Frequency RangeAvailability
D20-25Several MHzDay Only
E55-9020MHzDay, partially at night
F190-14030Mhz24 Hrs
F2200-25030Mhz24 Hrs
Ionosphere characteristics (note: F1 & F2 separate during daylight, merge at night).

VHF Radio

Primary characteristics:

  • Direct wave
  • Line-of-sight
  • Can be easily blocked or shielded by:
    • Terrain (e.g. mountains)
    • Natural obstructions (e.g. trees)
    • Unnatural obstructions (e.g. buildings)
Emaple of terrain blocking VHF radio.

What this means for an operator:

  • If you cant see the aircraft, neither can the radio.
  • No radio means “loss of comms.” protocol
  • Loss of comms. protocol means a failure to complete the mission!
  • Worst case: – Loss of comms. means loss of the aircraft!

HF Radio

Primary characteristics:

  • Used for communication over great distances.
  • Skywaves reflected by ionosphere.
Example of how different HF radio signals are reflected at different layers of the ionosphere.

Radio Class & Frequencies

Frequency Selection

SituationFrequencyAbb.Source
Outside Controlled AirspaceFlight Information Area (Glass G) Broadcast Area (e.g. Redcliffe)FIA/FISChart
Non-controlled (non-towered) AerodromeCommon Traffic Advisory Frequency Automatic Terminal Information ServiceCTAF ATISChart ERSA
Breakdown of Class G airspace (i.e. outside controlled airspace).

Frequency Selection – Class G

Depiction of Class G controlled airspace on a typical navigation chart for Sydney, Australia (source: Airservices Australia. (2014).
Depiction of Class G controlled airspace on a typical navigation chart for Melbourne, Australia (source: Airservices Australia. (2014).
Depiction of Class G controlled airspace on a typical terminal chart for Melbourne, Australia (source: Airservices Australia. (2014).

MULTICOM Frequency

At a non-towered aerodrome, or in an area where no specific frequency has been nominated on the aeronautical charts, there is a common “multicom” frequency that may be used.

This frequency is 126.7MHz.

Part 4 – High-Performance Batteries

Aim

To gain a basic understanding of the requirements and use of high-performance batteries commonly used to power small unmanned aircraft.

Objectives

At the end of this briefing you will be able to:

  • Discuss the characteristics of a lithium polymer cells.
  • Consider the vulnerabilities and dangers associated with lithium polymer batteries.
  • Explore the measures we can employ to maximise service life.
  • Discuss battery selection methodologies explore ‘safe’ disposal of depleted batteries.

Lithium Polymer Batteries

General Construction

DO NOT ATTEMPT TO DISASSEMBLE A BATTERY!

Lithium Polymer (Li-Po) batteries are a type of high-performance (high current output) power storage devices. This comes at a cost, as they have a much lower power density (i.e. lower capacity, low Ah/mAh) compared to batteries of a similar size.

A typical construction for a lithium polymer battery

Typical Cell

Think of a battery cell as a “ideal” cell in series with a resistance.

A battery broken down into it’s internal components.

Internal Resistance & Voltage Drop

Voltage drop of the internals of a battery.

Effect of Internal Resistance – Charging

Internal resistance during charging.

Result: Cell appears to be more fully charged than it actually is.

Effect of Internal Resistance – Discharging

Internal resistance during discharging.

Result: Cell appears more discharged than it actually is!

External Connections

Battery connectors.
Internal view of the balance connector wiring.

Internal Construction

Inside a Li-Po “foil pouch” cell you will find a long piece of very thin plastic film – the polymer!

Laminated onto the polymer are the thin lithium carbon coated aluminium & copper anode & cathode electrodes. These are laminated in an alternating pattern on the front and back side of the polymer separator film.

Everything will be saturated with a greasy solvent based organic electrolyte.

An “un-rolled” lithium polymer battery cell.

The long internal polymer film (which is over 7 feet long in the case of a 5000 mAh cell), is folded accordion style back and forth upon itself. The entire folded material is then heat sealed into the foil pouch, along with the gelled electrolyte.

As a matter of interest, the gelled electrolyte has a very sweet solvent smell, not dissimilar to nail polish remover, or acetone.

Charge & Discharge Cycle Chart

Typical charge and discharge cycle charts for Li-Po batteries at room temperature (20°C). These particular charts are based on Sanyo data.

Lithium polymer discharge cycle chart.

The cell voltage is reasonably constant out to about the 20% capacity state, and then falls off precipitously, similar to NiCad and NiMH cells.

Lithium-Based Battery Charge Regime

Lithium-based battery charge regime.

Battery Management

Service Life as a User

Fact: We are battery users, not battery manufacturers.

This means that we can only use the battery in accordance with manufactures directions!

From the user perspective, battery life can usually only be extended by preventing or reducing the cause of unwanted parasitic chemical effects which occur in the cells.

Shelf life & Cycle Life

Fact: Battery performance deteriorates over time regardless of whether the battery is used or not.

Shelf Life refers to how long a battery can remain on the shelf – in other words not being used – before it is no longer serviceable.

Cycle Life refers to the number of charge/discharge cycles a battery can be subjected to before it is no longer serviceable.

Cycle Life

The effects of voltage and temperature on cell failures tend to be immediately apparent, but their effect on cycle life is less obvious. We have seen above that excursions outside of the recommended operating window can cause irreversible capacity loss in the cells.

The cumulative effect of these digressions is like having a progressively debilitating disease which affects the life time of the cell. In the worst case, this can cause sudden death if you overstep the mark.

At about 15 ºC cycle life will be progressively reduced by working at lower temperatures. Operating slightly above 50 ºC also reduces cycle life but by 70 ºC the threat is thermal runaway.

The battery thermal management system must be designed keep the cell operating within its sweet spot at all times to avoid premature wear out of the cells.

Beware: The cycle life quoted in manufacturers’ specification sheets normally assumes operating at room temperature.

Li-Po Battery Service Life

Fact: Batteries have a finite service life.

This is due to the occurrence of unwanted chemical or physical changes to, or the loss of the active materials from which they were manufactured.

(Otherwise they would last for ever!)

Some Li-Po batteries have been rated by the company for 300+ cycles, but those numbers are usually in a ‘perfect’ setting. It is reasonable to expect around 200-250 cycles from any good/decent Li-Po manufacturer.

Battery life greatly depends on how the battery is used and stored. There are well documented cases of over 300 cycles with little drop off in measured performance (voltage under load, IR, etc, although capacity will tend to drop some with time).

Inappropriate care can make that number just about as low as you want. At the very least it will accelerate the capacity loss.

Limit the amount of discharge, store properly and routinely, etc.

Managing Battery Stock

Batteries – like all other aircraft components – are a controlled item. Batteries are a critical component, and come under the controlled maintenance program.

As a minimum there must be:

  • Battery pack numbering and identification:
    • Serial Number
    • Voltage and Capacity
    • Maximum Charge Rate
  • A Record or Log for each battery:
    • The Record or Log must be accessible
    • The Record or Log must be useable
    • The Record or Log must be sensible

Other useful information that could be recorded (where appropriate):

  • Record (Log) Usage Information:
    • Date / Time of Day / Flight Duration
    • Start capacity – end capacity = consumption in mAh
  • Record (Log) Charge Information:
    • Start time and finish time
    • Charge rate
    • End Capacity
  • Add operational information to Record (Log):
    • Ambient temperature
    • Maximum altitude (calculate operating temperature)
  • Installation considerations:
    • Vibration and Shock Absorption
    • Access
    • Identification
    • Cooling
    • Mounting
  • Storage considerations:
    • Charge as per manufacturers instructions
    • Identify and isolate from other equipment as necessary

Alphanumeric Designation

The alphanumeric designation for battery cells – as used in radio control applications – refers to both the number of cells in the battery pack, and the way in which those cells are interconnected.

Series (S): Denotes batteries connected in series. For example, 3S denotes a three-cell battery wired in series, thus multiplying the voltage to three times that of a single cell.

Parallel (P): Denotes batteries connected in parallel. For example, 2P would be two batteries connected in parallel to give twice the current capacity, but the voltage of one cell only.

Thus, a 3S2P battery contains 6 cells, and has three times the voltage and twice the capacity of any individual cell.

All cells should be identical if they are to be manufactured into a single “battery pack“.

Specific Notes on Managing Lithium Polymer Batteries

Main Points of Li-Po Batteries

Lithium ion polymer batteries, or lithium polymer batteries (abbreviated “Li-Po“) are rechargeable batteries which have technologically evolved from lithium ion batteries. Li-Po batteries contain a dry polymer suspended in an electrolytic gel (no metal-based conductive elements).

Li-Po Batteries are extremely volatile. The chemical compounds within the battery are flammable, and if not cared for correctly the battery can catch fire, or even explode.

Because of the volatile nature of Li-Po batteries, chargers specifically designed for use with Li-Po batteries must be used. Failure to do so incurs the very real risk of explosion and/or fire.

Battery output leads must never be allowed to short together, as immediate damage to the Li-Po battery will result.

Li-Po batteries must never be allowed to discharge below a certain point. It is therefore critical that low voltage cut-out devices are employed to protect the battery.

A battery that has been involved in a severe crash should be isolated for a reasonable amount of time (a few hours). It should never be immediately loaded into a vehicle, or transported from site until it is confirmed safe. This is because of the elevated risk of fire.

Li-Po in Comparison to Lithium-Ion

Lithium-Ion Batteries began their development in 1912, but did not become popular until they were adopted by Sony in 1991.

Lithium Ion Batteries have high energy-densities and cost less than lithium-polymer batteries.

Lithium-Ion batteries:

  • Do not require priming when first used
  • Have a low self-discharge
  • Suffer from aging – even when not in use
  • Usually come in a rigid plastic case
  • Have a nominal voltage of 3.7V
  • Don’t like near-freezing temperatures

Charged initially with a constant current, has a gradually increasing voltage. When the voltage limit per cell is reached, then the charger switches to a constant voltage with a gradually decreasing current flow.

Safe Transport

There have been very few cases of batteries suddenly exploding when they are not being used, abused or charged (i.e. during transport and storage).

Lithium batteries are commonly air-freighted protected by a few layers of bubble wrap and small versions are carried around in mobile phones. Should it be required to ship a battery pack, care must be taken when packing to ensure that it cannot be physically damaged.

It has been reported that some Li-Po battery fires have been caused when a dog was attracted to the smell of a lithium battery – and bit it.

Charging & Safety

The majority of lithium battery fires occur during charging, therefore charging should only take place where a fire cannot spread. Fire safety must always be a prime concern when working with Li-Po batteries.

Additionally it is most strongly recommended that Li-Po batteries are not charged inside a vehicle, and in particular a moving vehicle.

Charging in an purpose built and approved fire/explosion resistant bag is recommended. Alternatively a heat-resistant ceramic container with a loose fitting lid as flames, smoke and gas are released should the battery “vent”. Metal containers can be used, but ensure the charging wires cannot be cut or shorted.

Keep batteries separated so that a fire cannot damage other batteries. The charging container should be kept away from anything flammable.

Battery Charging & Charge Balancing

Many Li-Po batteries, particularly larger packs, come with a second, smaller, multi-wire plug – which is to be used for balance charging.

Balance charging simply ensures that all individual cells within the battery pack are at the same voltage. If a battery is not balanced, some cells may be overcharged, others may be over-discharged. In either case the life of the battery pack will be compromised.

Lithium batteries are not automatically balanced by applying a small “overcharge” in the same way that nickel-cadmium or lead-acid batteries may be balanced.

Note: Not all balancers are compatible with all chargers – some research into compatible types will be necessary in order to avoid battery damage.

For example, some balancers are only able to balance a small amount of amps, which, depending on the Li-Po cell, may not be enough to achieve a balanced state. Some of the ‘newer’ Li-Po chargers are able to individually charge each cell using the balancer plug, thus eliminating the need for a separate balancer, and at the same time ensuring sufficient power to complete the balancing process.

Storage Tips & Techniques

Extracting the longest service life out of a battery packs is of prime concern. One of the key factors contributing to the service life is correct storage.

The greater portion of the service life of many battery packs is spent in storage. The conditions that a battery pack is exposed to during storage directly impact on the achievable service life from the battery pack.

Additionally a unique characteristic of Li-Po batteries is that their life span is dependent on aging from time of manufacture, not just a number of charge/discharge cycles. An older battery will not perform as well as a new one, due solely to its age.

This limitation is not widely publicized, and consequently is not well known. This is because as Li-Po battery ages, it’s internal resistance increases.

Under load the effect of internal resistance is to cause the battery terminal voltage to drop, which in turn reduces the maximum current that the battery can provide to the load. To add to this phenomena – as Li-Po batteries age, usable capacity is lost.

Cell Storage – Voltage

A fully charged Li-Po cell will produce a terminal voltage of approximately 4.2 volts. Li-Po’s are different from other battery chemistries as they should never be stored fully charged. In fact, LI-Po batteries should be stored approximately “half full”, or at 50 State of Charge (SoC).

Many of the newer Li-Po battery balance chargers include a “Storage Mode”, which charges the pack to the proper reduced voltage state for storage purposes.

Some commercial chargers charge cells to 3.85Vdc in Storage Mode.

Storing battery packs at the proper voltage level is the simplest thing you can do to lengthen their usable life span (assuming of course proper application).

‘Storage’ should not only be considered as a long term (e.g. “over the winter” situation). Even if, for example, you only fly on weekends, these battery packs are technically in storage all week – week after week – during the entire flying season. Those cumulative hours can add up slowly degrading the battery packs.

Cell Storage – Temperature

Li-Po batteries produce energy via a chemical reaction that occurs inside sealed foil envelopes. The output power is produced by a chemical reaction. The aging/degrading process is also in reality a chemical reaction.

A chemical reaction doubles its speed for every ten degrees increase of ambient temperature.

It is for this reason that Li-Po batteries do not perform as well in cold weather. Cold “slows down” the chemical reaction process – something we need to be aware of when anticipating aircraft performance.

Reducing storage temperature slows the chemical reaction of the aging/degrading process, however there is a limit as to how cold is acceptable. Li-Po batteries should not be for example frozen solid. Laboratory testing has determined that the typical household refrigerator (0 to +5 degrees C) is the perfect storage place.

Li-Po battery packs should be placed in plastic zip top storage bags prior to placing them in the refrigerator for storage. When removed from the refrigerator prior to use, leave the batteries in the zip top storage bag to prevent any atmospheric moisture from condensing on them as they warm. After the batteries have attained room temperature, that may be used as normal.

Storage & Battery Degradation

Storage Temperature40% Charge100% Charge
0 °C (32 °F)2% loss after 1 year6% loss after 1 year
25 °C (77 °F)4% loss after 1 year20% loss after 1 year
40 °C (104 °F)15% loss after 1 year35% loss after 1 year
60 °C (140 °F)25% loss after 1 year40% loss after 3 months
Permanent capacity loss versus storage conditions (source: www.batteryuniversity.com)

Over Discharging

Li-Po batteries are intolerant of over discharging, and tend to die if discharged below approximately 2.5 V.

In operation, controller circuitry should prevent the cell voltage from dropping below 3.0 V.

Cell temperature should never exceed 90 °C in order to prevent the internal separator polymers from melting and allowing plate shorting through physical contact.

Batteries with discharge rates of 20C or 25C are commonly available on the commercial market. In battery discharge terminology, each “C” is a discharge current equivalent to the value of the energy capacity of the cell (it is not the abbreviation for the Celsius degree unit).

In the case of a 1,200 mAh rating, 1C is equal to a discharge current of 1,200 mA, or 1.2 amps. A 10C cell can deliver a continuous current to a load of 10 x 1.2 A = 12 A during its discharge cycle.

Safe Disposal of Failed Li-PO Batteries

FOLLOW THE MANUFACTURERS DIRECTIONS FOR SAFE DISPOSAL!

Unlike others, lithium-polymer batteries are environmentally friendly.

It must be remembered that should the outer case of a Li-Po battery be compromised, the lithium inside is highly volatile and will react violently with water.

For safety reasons, it is recommended that Li-Po cells be fully discharged before disposal.

If the battery is physically damaged, discharge is not recommended. Li-Po batteries must also be cool before proceeding with the disposal instructions.

Safe Discharging

For Li-Po packs rated at 7.4V and 11.1V, connect a 150 ohm resistor with a power rating of 2 watts to the pack’s positive and negative terminals to safely discharge the battery pack.

Connecting the battery pack to an Electronic Speed Controller/motor system, and allowing the motor to run indefinitely until no power remains to further cause the system to function is not an preferred method of discharging the battery pack.

Discharge the battery pack until its voltage reaches 1.0V per cell or lower. For resistive load type discharges, discharge the battery for up to 24 hours.

Safe Disposal

After discharge, submerse the battery into bucket or tub of salt water. This container should have a lid, but it should not need to be air-tight. Prepare a plastic container (do not use metal) of cold water. And mix in 1/2 cup of salt per gallon of water. Drop the battery into the salt water. Allow the battery to remain in the tub of salt water for at least 2 weeks.

Remove the Li-Po battery from the salt water, wrap it in newspaper or paper towels and place it in the normal trash.

When neutralised these batteries are “reported” to be landfill safe.

Note: Some cells might react to any attempt to discharge them by bloating more. Should this occur, or should any doubt arise as to the stability of the cells, the cells should immediately be placed into a saltwater bath. It may take several days (or weeks) for a fully charged cell to deactivate in saltwater, however it will eventually deactivate.

Li-Po Battery Safety Summary

  • Keep Li-Po batteries in a cool environment
    • Do not leave Li-Po batteries in direct sunlight. Elevated battery temperatures increase the likelihood of the battery chemicals reacting in a hazardous manner.
  • Do not overcharge your battery
    • Excessive charging will cause the battery pack to heat up, expand, or explode.
  • Handle Li-Po batteries carefully
    • Try to prevent holes being punctured into the battery. The chemicals inside the battery may leak out. These chemicals may become volatile in contact with air.
  • Never leave Li-Po battery unattended while charging
    • Ensure the correct charge settings for the battery are being used.
    • The charging area should be away from any flammable material.
    • If smoke appears, or there are signs of the battery expanding, or “puffing out”, disconnect the battery charger from the wall socket, eliminating any further flow of energy into the battery.
  • Use Li-Po specific chargers only
    • EXTREMELY IMPORTANT: Using a NiCd or NiMh charger will create an unwanted reaction within the battery that may result in a fire. Remember to only use Li-Po specific battery chargers!
  • Never leave Li-Po batteries plugged to an Electronic Speed Controller (ESC)
    • Li-Po batteries are always ageing, even when they’re not connected. The chemicals inside the Li-Po battery are extremely volatile.
    • This also puts a heavy reliance on the system failsafes, which are the only thing from stopping a motor powering up if the battery is connected.
  • Never arc the positive and negative terminals
    • A positive-negative short creates a continuous flow of uncontrolled energy through the battery, with nowhere for the energy to be released.
  • Check the battery after each run period
    • Check for signs of puffing, for severed or cut wires, for dents and/or damage, and the overall condition of the battery.
    • If the battery is starting to puff out, swell, or looks like it has been punctured, do not continue to use it.
    • Charging a damaged battery MUST NOT BE ATTEMPTED!
  • Chemical reactions of Li-Po battery are not instantaneous
    • Be careful if you see a battery starting to smoke without fire. Although it has not yet reached the reaction of a fire, it is highly likely that it will reach the stage of combustion, and burst into flames.
    • Remember, if you see smoke, UNPLUG THE CHARGER FROM THE WALL SOCKET AND MOVE THE BATTERY TO A SAFE LOCATION.
    • Wait at least 10-15minutes before moving it again just to be safe.
  • Never leave Li-Po batteries in your car
    • This is for the same reason why you should store your Li-Po Batteries in a cool environment.
    • Heat = Reaction. Reaction = Expansion. Expansion = Cause for burning! BE AWARE!
  • Do not leave batteries unattended with children
    • Children do not know how to handle a battery safely. Be extremely careful and limit access to batteries.
    • There are no age restrictions with respect to the use of batteries, however common sense is required.
  • The “C” rating – and what it means
    • A 3S 11.1 Li-Po battery with 5000mAh have 1C = 5 ampere.
    • If the battery is rated for 25C continuous use that means it can output 125 ampere, or almost 1400 watt.

Part 3 – Pulse Width Modulation

Aim

To gain a basic understanding of the principles of pulse width modulation, which is commonly used as motor and servo control signals in small unmanned aircraft.

Objectives

At the end of this briefing you will be able to:

  • Discuss the basic principles of operation for pulse width modulation.
  • An understanding on how pulse width modulated signals are generated.

Pulse Width Modulation

What is Pulse Width Modulation?

Pulse Width Modulation (PWM) is a means of generating an electrical pulse of a specific width (i.e. duration) can be altered.

PWM signals with different duty cycles.

PWM is a process mainly used for getting an analog signal using a digital source.

H-Bridge Inverters – Creating AC from DC

Single-phase H-bridge (voltage source) inverter topology:

Switching rules:

  • Either A+ or A- is closed, but never at the same time*
  • Either B+ or B- is closed, but never at the same time*

Corresponding values of Va and Vb:

  • A+ closed ⇒ Va = Vdc
  • A- closed ⇒ Va = 0
  • B+ closed ⇒ Vb = Vdc
  • B- closed ⇒ Vb = 0

* Same time closing would cause a short circuit from Vdc to ground (i.e. a “shoot-through“). To avoid shoot-through when using real switches (i.e. there are turn-on and turn-off delays) a dead-time or blanking time is implemented.

H-Bridge Inverters – Square Wave Modulation

How a H-Bridge creates a PWM signal.

H-Bridge Inverters – Square Wave Operation

The different outputs of a H-Bridge inverter.

The Vab = 0 time is not required but can be used to reduce the rms value of Vload.

Lagging Current

Many loads have lagging current – consider an inductor!

There must be a provision for voltage and current to have opposite signs with respect to each other.

Examples of voltage and current having opposite signs.

H-Bridge Inverters – Current Flow

Load current can always flow, regardless of switching state:

Example of current flowing left to right through the load.
Example of current flowing left to right through the load in a different direction.

H-Bridge Inverters – Where the Current is Goes

Example of load consuming power.
Example of load generating power.

H-Bridge Inverters – Circuit Isolation

The four firing circuits do not have the same ground reference. Thus, the firing circuits require isolation.

Example of why ground isolation is needed in a H-Bridge inverter.

Signal Generation

Pulse Width Modulation through Harmonics

Harmonics with square wave modulation.

Sine Waves with Digital Signals

Question: How can a sinusoidal (or other) input signal be amplified with low distortion?

Answer: The switching can be controlled in a smart way so that the FFT of Vload has a strong fundamental component, plus high-frequency switching harmonics that can be easily filtered out and “thrown into the trash”

Sine wave constructed from digital signals.

Unipolar Pulse Width Modulation

Vcont is the input signal we want to amplify at the output of the inverter. Vcont is usually a sinewave, but it can also be a music signal.

Rules for creating a unipolary PWM signal.

Vtri is a triangle wave whose frequency is at least 30 times greater than Vcont.
Ratio ma = peak of control signal divided by peak of triangle wave.

Unipolar PWM using H-Bridge Inverters

A unipolar PWM signal created using a H-Bridge Inverter.
Deconstructing the signals of a unipolar PWM signal.
The idealised waveform to create unipolar PWM signal.

Amplification of Unipolar PWM

Ratio ma = peak of control signal divided by peak of triangle wave.
Ratio mf = frequency of triangle wave divided by frequency of control signal.

Load voltage with ma= 0.5 (i.e. in the linear region)
Load voltage with ma = 1.5 (i.e. over-modulation)

Voltage Ratios in Single-Phase Inverters

Variation of RMS value of no-load fundamental inverter output voltage (V1rms ) with ma. For single-phase inverters ma also equals the ratio between the peak output voltage and the input Vdc voltage.

The linear, over-modulated, and saturated modulation zones.

Load Frequency Components

RMS magnitudes of load voltage frequency components with respect to Vdc / √2 for ftri >> fcont.

H-Bridge Inverter Performance Analysis

100Hz Signal as Input, Inverter Output
FFT of 100Hz Inverter Output
Inverter Performance with Music Input

Summary

  • Very efficient
  • Distortion higher than linear amplifier, but a linear amplifier has, at best, 50% efficiency
  • Perfectly suited for motor drives where voltage and frequency control are needed
  • Well suited for bass music amplification, such as automotive applications, or where high power is more important than a little loss in quality

Part 2 – Electric Motors

Aim

To gain a basic understanding of the principles of electric motors, specifically the types commonly used in small unmanned aircraft. Also, to gain a sound understanding of the considerations and concerns present when working with electric motors and the effects they can have on other on-board systems.

Objectives

At the end of this briefing you will be able to:

  • Discuss the BASIC principles of operation of an electric motor, of the types commonly used in small unmanned electric aircraft
  • Understand Voltage, Current and Resistance
  • Describe how to reverse the direction of rotation of the electric motors discussed
  • List and describe the considerations and concerns when working with electric motors and their associated equipment
  • Nominate the implications and possible effects  on other equipment on-board the aircraft when an electric motor is used

Electricity

Describing Electricity

Voltage: The potential difference in charge between two points in an electrical field (also called electromotive force).

Current: The rate at which electric charge flows past a point in a circuit. In other words, current is the rate of flow of electric charge.

Electrical impedance: The measure of the opposition that a circuit presents to a current when a voltage is applied. 

Resistance: Once of the forms of impedance.

The Water Analogy

Consider a water tank at height above the ground. At the bottom of this tank there is a hose.

The pressure at the end of the hose represents voltage.

The water in the tank represents charge. The more water in the tank, the higher the charge, the more pressure is measured at the end of the hose.

Resistance is similar to the size of the hose. A big hose means lots of water flows (LOW resistance). A small hose means only a little water flows (HIGH resistance).

Think of this tank as a battery! We store energy, and then release it. If we drain some of the water out of our tank the pressure created at the end of the hose will go down. This represents decreasing voltage.

The Formula

Voltage = Current x Resistance
Or: V = IR

A simple electric circuit.

If  the battery is at 1.5V, and the lamp draws 0.5A, the RESISTANCE is:

V=IR
Then,
R=V/I
Therefore,
R = 1.5/0.5 = 3 Ohms (Ω)

Electric Motors

How Does an Electric Motor Work?

The answer is a circuit and magnets!

The magnetic field of a flowing current.

The voltage across the battery will cause a current (“I”) to flow through the wire.

Current flowing through the wire will cause a magnetic field to be created around the wire.

The Permanent Magnet DC Motor

The heart of any motor! A Direct Current (DC) motor uses a current flowing in one direction to cause the motor to spin.

When a current is passed through a coil of wire it becomes an “electromagnet”!

The magnetic field around an electromagnet.

Using a simple wire will work, but not very well. Placing a (ferrite based) core in the coil concentrates and focuses the magnetic field.

This is very predictable, and the “Right Hand Rule” can be used to determine the “North pole” and the “South pole”.

Magnetic Attraction & Repulsion

Magnetic attraction.
Magnetic repulsion.

A Simple Motor (Magnetic Field)

A constant magnetic field to start as the basis of the motor.
A direct current to create a second magnetic field.
Putting the two together makes movement (the “Elastic Band Theory”)!

To get the DC motor to keep spinning (and not “elastic band”), then we need to switch the direction of the current!

This is usually done with brushes and a commutator.

Adding brushes & commutator (to the bit that spins).
A full DC motor that will keep rotating!

Three-Phase Motors

What is a Three-Phase Motor?

What if we don’t want to use brushes and a commutator (as these will wear out eventually)?

A three-phase motor uses alternating current in a specific manner to avoid needing brushes and a commutator!

The Basic Principles

A basic triangular sine wave (it’s a start!).
Creating a properly referenced three-phase sine wave.
A properly referenced three-phase sine wave.

Putting the Phases Together

The “red” phase.
The “yellow” phase.
The “blue” phase.

Making it Spin – Time Interval 1

The input signal at time interval 1.
The motor phases at timer interval 1.

Making it Spin – Time Interval 2

The input signal at time interval 2.
The motor phases at timer interval 2.

Making it Spin – Time Interval 3

The input signal at time interval 3.
The motor phases at timer interval 3.

Reversing the Spin Direction

To reverse any 3 phase motor swap any two phases!

Making it Spin in Reverse – Time Interval 1

The reverse input signal at time interval 1.
The reverse motor phases at timer interval 1.

Making it Spin in Reverse – Time Interval 2

The reverse input signal at time interval 2.
The reverse motor phases at timer interval 2.

Making it Spin in Reverse – Time Interval 3

The reverse input signal at time interval 3.
The reverse motor phases at timer interval 3.

Three-Phase Motors for Small Unmanned Aircraft

Brushless Electric Motors

Brushless electric motors come in several different physical configurations.

Different brushless electric motors.

In the inrunner configuration, the permanent magnets are part of the rotor. Three stator windings surround the rotor.

In the outrunner configuration the stator coils form the centre (core) of the motor, while the permanent magnets spin within an overhanging rotor which surrounds the core.

Common Terms – The “kV Rating”

The term “kV” – as generally used by hobbyists – refers to the so-called rpm constant of a motor.

Expressed in the most simple terms, this alludes to the number of revolutions per minute that the motor will develop when 1V (one Volt) is applied to the motor with no load attached.

A motor with a kV rating of 4600, and a 12V supply, 4600 x 12 = 55,200 RPM. This is the maximum RPM the motor can achieve under no load.

What does this mean?

  • A motor with a higher kV will have more top end speed, but not as much acceleration/torque
  • A motor with a lower kV will not be as fast, but will accelerate faster.
  • The KV figure allows a comparison of similar motors!

Common Terms – Motor Turns

Motor Turns is the same for either brushed motors or brushless motors. The word “turns” stands for the number of turns of wire around each of the motor’s rotor poles.

  • The higher the number of wirings/turns means less top speed, but higher acceleration/torque.
  • The lower the number of turns equals higher top end speed and lower torque/acceleration.

For example, a motor with a turn rating of 5.5 will have less acceleration/torque but higher top speed than a motor with a 12 turn rating.

Common Terms – Current Rating (Amps)

The max current rating is the maximum amount of current that a motor is able to handle safely. This current is measured in Amps. The continuous current rating of a motor is the Amps that a motor can handle safely over a long period of time.

It is a great idea to find an ESC that has a current rating that is higher than your motor by at least 20%. It will be a good safety cushion.

The estimated current rating of a motor is usually on the factory specs sheet, however other factors affect the actual current that a motor will draw. Such things typically include the kV rating of the motor, the battery voltage, how heavy the aircraft is, prop size. The harder a motor needs to work to reach it’s top speed, the higher the current will be.

Common Terms – Watts

Watts are the power rating of the Motor.

The simple math here is Amps x Volts = Watts.

The motor should have a watt rating on its specification sheet, e.g. “180W”. This is the amount of power that the motor should produce safely. Running anything over this rating could damage the motor, especially over an extended period.

Common Terms – Motor Efficiency

The efficiency of a motor is generally a function of the quality of the motor. A 70% efficient motor produces 70% power and 30% heat. A 85% efficient motor produces 85% power and 15% heat.

If the battery is supplying the Motor/ESC combination with 180 watts, an 85% efficient system will produce 153 watts (85%) power, with 27watts of heat. (27 Watts of heat is capable of melting solder).

A Typical Brushless Motor

A Turnigy SK3 1340kV Brushless Motor

Motor Specifications:

  • Turns: 24T
  • Voltage: 2~3S LiPo (7.4~11.1V, max: 12.6V)
  • RPM/V: 1340kv
  • Internal resistance: 0.052 Ohm
  • Max Loading: 28A
  • Max Power: 375W
  • Shaft Dia: 4.0mm
  • Bolt holes: 25mm
  • Bolt thread: M3
  • Weight: 76g
  • Motor Plug: 3.5mm Bullet Connector

Summary

You should now be able to:

  • Discuss the basic principles of operation of an electric motor, of the types commonly used in small unmanned electric aircraft.
  • Describe how to reverse the direction of rotation of the electric motors discussed.
  • List and describe the considerations and concerns when working with electric motors and their associated equipment.
  • Nominate the implications and possible effects  on other equipment on-board the aircraft when an electric motor is used.

Part 1 – Propellers

Aim

To gain a basic understanding of the principles of propeller aerodynamics, and how they are used to create thrust for unmanned aircraft.

Objectives

At the end of this briefing you will be able to:

  • Describe the naming convention for propellers
  • Discuss the meaning of the pitch of a propeller
  • Discuss propeller pitch and performance

Propeller Design

Propellers in Simple Terms

The aircraft propeller consists of two or more blades and a central hub to which the blades are attached.

Each blade of an aircraft propeller is essentially a rotating wing.

As a result of their construction, the propeller blades are like aerofoils and produce forces that create the thrust to pull, or push, the aircraft through the air.

The engine furnishes the power needed to rotate the propeller blades through the air at high speeds, and the propeller transforms the rotary power of the engine into forward thrust.

Propellers for Unmanned Aircraft

Examples of different sizes of propellers for unmanned aircraft.

Pitch

Pitch is the displacement a propeller makes in a complete spin of 360° degrees.

Example of how propeller pitch effects the translational motion.

This means that if we have a propeller of 40” pitch it will advance 40 inches for every complete spin as long as this is made in a solid surface; in a liquid environment, the propeller will obviously slide with less displacement.

The pitch concept is not exclusive to propellers, other mechanical devices like screws also use it. For instance, a screw with 10 mm of pitch will advance 10 mm for every complete turn of the screwdriver.

Propeller Blade Angle

Relative wind speed affecting the angle of attack of a propeller blade.

Fixed Pitch

Fixed-pitch and ground-adjustable propellers are designed for best efficiency at one rotation and forward speed.

They are designed for a given aircraft and engine combination. Since the efficiency of any machine is the ratio of the useful power output to the actual power input, propeller efficiency is the ratio of thrust horsepower to brake horsepower. Propeller efficiency varies from 50 to 87 percent, depending on how much the propeller “slips.”

Propeller slip is the difference between the geometric pitch of the propeller and its effective pitch.

Geometric pitch is the theoretical distance a propeller should advance in one revolution; effective pitch is the distance it actually advances.

The Twist on a Propeller

The reason a propeller is “twisted” is that the outer parts of the propeller blades, like all things that turn about a central point, travel faster than the portions near the hub.

Propeller blade twist.

If the blades had the same geometric pitch throughout their lengths, portions near the hub could have negative AOAs while the propeller tips would be stalled at cruise speed.

Propeller Pitch and Efficiency

The pitch of the propeller is generally chosen to provide the speed characteristic of the aircraft for the purpose required.

Increasing the blade pitch increases the blade drag, and decreasing the blade pitch decreases the blade drag.

A larger (coarser) blade angle, for a given RPM, will adsorb more power and require more torque to turn it at the requested RPM.

Usually 1° to 4° provides the most efficient lift/drag ratio, but in flight the propeller AOA of a fixed-pitch propeller varies — normally from 0° to 15°. This variation is caused by changes in the relative airstream, which in turn results from changes in aircraft speed. Thus, propeller AOA is the product of two motions: propeller rotation about its axis and its forward motion.

Propeller Designation

Propellers are designated by two numbers:

  • Diameter
  • Pitch

A propeller designated as a 12-6 propeller is therefore:

  • 12″ in diameter
  • 6″ of pitch.

…where pitch is the distance a propeller will move forward in one revolution in a perfect fluid (which air is not).

Theoretically a 6″ pitch will move forward 6″ with each complete (360°) revolution of the propeller.

How Pitch Affects Propulsion

The properties of a propeller with high pitch:

  • High speed flight
  • Poor Acceleration
  • Poor Climb
  • Can be difficult to slow down for landing

The properties of a propeller with low pitch:

  • Low speed flight
  • Good Acceleration
  • Good Climb
  • Finer speed control throughout throttle range – particularly at low throttle settings

Pitch in Simple Terms

An easy way grasp the concept of propeller pitch is to draw a parallel to the gearing in a car.

Low pitch propellers = low gear in your car.

It will get you up hills well but will not take you any where fast.

High pitch propellers = Beginning your drive in fifth gear.

It will take forever to accelerate to speed but the plane is cruising when it gets there.

Propeller Performance

Propeller Balance

An out of balance propeller can be the cause of a lot of problems.  Some of these problems manifest as:

  • Prevents the engine from developing full power.
  • Causes excessive vibration through the airframe.
  • Causes excessive vibration through on-board electronics, leading to premature failure.
  • Causes fuel foaming which can cause the engine to run ‘lean’.
    • The result is the engine loosing performance and power, to stall, or just not run smoothly.

This is all amplified in a smaller aircraft.

Trimming Balance

Before you attempt to balance a propeller, be sure to clean it.

Most propellers are close to being in balance when purchased, so they should only need a small amount of work to bring them into perfect balance. 

If the propeller is severely out of balance – return it because too much material would have to be removed which would significantly change the shape of the blade.

Propeller Balancing Device

If one blade is heavier than the other, then the usual method to bring the propeller into balance is to remove material from the heavy blade using sandpaper.

Trimming Heavy Propellers

Do not trim the tip of the heavy blade!

Although the blade may balance statically, it will not be balanced when it starts to spin, because of unequal mass distribution.  Material is generally removed from the face (front) of the propeller or from the back of the propeller.

Generally all that is required is to sand the face a little.

Propeller Tracking

Occasionally you may encounter a propeller that does not track properly.  Either the mounting hole is off-centre or the hub is not square to the plane of rotation. 

In either case, if the propeller is noticeably out of track you should not use it.

It is easy to see if the propeller is tracking correctly.  Stand back for safety and look at the propeller from the side and from the rear.

From the side, both tips should be clearly visible in the same line.  If you see two lines, then the hub is not square to the plane of rotation.

The recommended procedure is to return the propeller – it is defective, and may require too much modification to ‘repair’.

Selecting Motors & Propellers

Propeller Selection

Beware the “hobby mentality“

The propeller should be chosen to match the aircraft — not the engine. An appropriate engine should then be chosen! 

Consider this. Mounting a racing propeller to a scale WWI aircraft will severely limit the model as an early warbird has so much airframe drag that the propeller will never be able to deliver it’s full potential, with the result that the aircraft will be a sluggish flyer at best.

Additionally, using too ‘slow’ a propeller – one with low pitch – on a model intended to go fast may prevent the aircraft from gaining enough speed to fly at all. A basic mistake is finding a propeller that works great – with a certain engine in a certain aircraft – and then imposing that propeller on that engine regardless of the aircraft!

Number of Blades

With ‘model’ sized aircraft the most efficient propellers are two bladed.  Because the diameter of our propellers tend to be small, multiple blade propellers disturb the air that the trailing blade is entering tending to make them less efficient.

Generally, with smaller aircraft, for best overall performance, it is recommended to utilise 2-blade propellers.

Matching Propeller and Motor

Propeller-Motor Thrust Output

The Reality of Motor and Propeller Selection

Test & Verification Procedure (Actual procedure – V-TOL Aerospace):

  1. The propeller was fitted to the motor, which was mounted on the scales to provide down thrust, pushing against the scales.
  2. The current meter was setup in line with the battery and Electronic Speed Controller to measure current drawn by the motor.
  3. The servo checker was setup to control the motor through the ESC.
  4. A camera was mounted such that it could see the current meter and the display on the scales.
  5. For safety the video display and servo checker were operated from behind a safety barrier.

Test Results

ThrottleVoltsAmpsThrust (g)
μs%9×4.59×69×4.59×69×4.59×6
1000012.5712.570000
11001012.5512.550.30.36560
12002012.5212.491.61.7165150
13003012.4712.423.13.7285290
14004012.2712.216.27.6480500
15005012.1512.0620.312.5680705
16006011.9711.9116.119.6900910
17007011.7811.7322.825.811401085
18008011.5211.4429.434.513301240
19009011.3911.0638.139.515251345
200010011.1311.0138.944.315501390
Collected thrust data for differently sized propellers
ThrustVoltsAmpsWatts
(g)8×69×69×4.58×69×69×4.58×69×69×4.5
10012.412.512.51.61.10.919.8413.7511.25
20012.412.412.53.42.22.142.1627.2826.25
30012.312.412.45.53.83.567.6547.1243.4
40012.212.412.38.75.54.9106.1468.260.27
50012.112.312.312.77.86.7153.6795.9482.41
6001212.212.216.89.98.7201.6120.78106.14
70011.812.112.1221310.7259.6157.3129.47
80011.7121226.215.713.4306.54188.4160.8
90011.711.911.934.118.415.5398.97218.96184.45
100011.611.711.739.223.418.1454.72273.78211.77
1100—11.611.6—27.622.6—320.16262.16
1200—11.411.6—33.324.5—379.62284.2
1300—11.311.4—37.828.9—427.14329.46
1400—11.211.4—44.232.4—495.04369.36
1500——11.2——38.1——426.72
Collected power draw data for different thrust values

Given the test data, and noting that cruise speed for the condor aircraft is attained at 8A/100W with a 9 x 4.5 propeller, it can be seen that the most efficient propeller to produce the required amount of thrust is the 9 x 4.5 propeller.

Safety

Hazards of Propellers

Safety must always be first and foremost in your thoughts when handling unmanned aircraft, or components from unmanned aircraft.

  • Propellers spin at relatively high speed.
  • Propellers are made from hard material.

This is why should we pay special attention to the propeller when completing an inspection of an aircraft!

What happens when things go wrong?

Example of a propeller that was broken while spinning.
A broken propeller that was found after an incident during an indoor test.

All that stopped the blade segment from passing all the way through the partition was the fabric on the other side!

Summary

You should now be able to:

  • Describe the naming convention for propellers.
  • Discuss the meaning of the pitch of a propeller.
  • Discuss propeller pitch and performance.

Part 3 – Flight (Multirotors)

Aim

To gain a basic understanding of the principles of aerodynamics, as they apply to unmanned aircraft.

Objectives

At the end of this briefing you will be able to:

  • Describe the aerodynamic principles of multirotor flight and how multirotor aircraft attitude is controlled
  • Outline considerations when Hovering In Ground Effect and operating in confined spaces
  • Outline the normal and non-normal flight modes available for Academy multirotor flight operations

Movement

Aircraft Axes

MovementAxesLimits
PitchLateral35o (180o/sec)
RollLongitudinal35o (180o/sec)
YawNormal90o/sec

Motor Configuration

Note: Refer Specifications for YOUR airframe

To facilitate flight path control:

  • The motor numbering sequence and direction of rotation are linked to the orientation of the autopilot
  • The firmware interprets any control inputs and commands the correct motor(s) in the correct sequence to change motor speed (RPM)

Aerodynamics – Rotary Wing Flight

  • Aerofoil (rotor) is rotated by the aircraft power plant
  • Air is drawn down from above and accelerated though rotor disc
  • There will be lower pressure above the rotor, and higher pressure below the rotor
  • There will be a large blade tip vortex
  • Maximum downwash velocity will occur approximately two rotor diameters below the disc

The Multirotor as a System

Flying a Multirotor

Question: Is it possible to take the theory we have learned for fixed wing aircraft and make it apply to multirotor aircraft?

Vertical Flight

Each rotor provides ¼ of TRTR

Horizontal Flight – Theory

Control inputs required ⟹ Pitch & Roll ⟹ Tilting the TRT

From previous theory, for horizontal flight:

  • TRT needs to increase
  • RTVC supports weight
  • RTHC moves airframe along flight path

Horizontal Flight – Example

Pitch Forward1234
HoverKKKK
Entry⇓⇑⇓⇑
MaintainKKKK
Exit⇑⇓⇑⇓
HoverKKKK
Roll Right1234
HoverKKKK
Entry⇓⇑⇑⇓
MaintainKKKK
Exit⇑⇓⇓⇑
HoverKKKK

Yaw

Newton’s Third Law: For every action there is an equal and opposite reaction.

MotorsRotationEffect of Torque
1 & 2Counter-clockwiseClockwise
3 & 4ClockwiseCounter-clockwise
Right Yaw1 & 2 ⇑3 & 4 ⇓
Left Yaw1 & 2 ⇓3 & 4 ⇑

Operating in Confined Spaces

  • Low pressure (i.e. suction) in region above disc and region of the tip vortex
  • Objects such as poles, walls or ceilings will interfere with the flow similar to the strong winds felt in alleyways around bases of tall buildings close together – venturi effect)
  • Increased air velocity will lower the pressure
  • Airframe likely to be sucked into collision with object

Operations

Multi-Crew Operations – Crew Stations

Person stationed at GCSPerson stationed with hand controller
1st Pilot / Captain2nd Pilot / First Officer
Responsible for:
– Start, continuation, diversion and end of a flight by the aircraft
– Operation and safety of the aircraft (including payload) during flight time
– Conduct and safety of members of the crew		Actively support the Captain in:
– Safe flight outcomes
– Appropriate operation of the aircraft and payload
– Achievement of mission objectives (as planned and subsequently amended)
Crew stations.

Multi-Crew Operations – Responsibilities

Pilot Flying (PF)Pilot Monitoring (PM)
Person controlling the aircraft:
– Direct manipulation of the flight controls and flight path; or
– Entering commands into a navigation system (e.g. GNSS) that is coupled to an autopilot		Person monitoring the aircraft:
– Monitoring flight path and other aspects of operational performance
– Authorised to TAKE CONTROL if undesired aircraft state develops and remains uncorrected
Crew responsibilities.

Undesired Aircraft State: aircraft position or speed deviations, misapplication of flight controls, or incorrect system configurations associated with a reduction in margins of safety

Flight Modes

ModeAnnunciationSelectedFunction
StablisedSTABLabelled switch on right side hand controller– Co-pilot is Pilot Flying with autopilot engaged (or stability board)
– Continuous control inputs required to maintain station (i.e. position & height)
Height HoldHHLabelled switch on right side of hand controller– Co-pilot is Pilot Flying with autopilot engaged (Barometric sensor on autopilot)
– Power lever in neutral position = aircraft will maintain height with no pilot input
– Co-pilot makes roll / heading inputs to maintain station / manoeuvre laterally
NavigationNAVON and OFF labelled position switch on left side of hand controller– Only selected ON when authorised by Captain
– When selected ON, Captain becomes Pilot Flying
– When selected ON, autopilot will command the aircraft to navigate vertically and laterally to the waypoint from the Active Flight Plan that is annunciated on the Captain’s Primary Flight Display. Waypoint sequencing will automatically continue
– When selected OFF, Co-Pilot becomes Pilot Flying in either HOV or STAB mode depending on that switch position
Return to LaunchRTLON and OFF labelled position switch on left side of hand controller– GNSS coupled to autopilot
– Airframe will track direct from present position to starting point
– If > 50 ft AGL, present height will be maintained
– If < 50 ft AGL, airframe will climb to 50 ft AGL then track to launch site
– At launch site, hover for 5 secs, autoland, then motor shutdown and lock
– Mode cancelled by cycling RTL switch to OFF
Normal operations.

Emergency Operations

PriorityStateConditionsAction
1Critical BatterySTAB, HH or NAV; GNSS; and
> 2m from launch position		– RTL then autoland
– GCS annunciations (Low Battery; Critical Battery – RTL)
STAB, HH or NAV; and / or
< 2m from launch position		– Autoland
– GCS annunciations (Low Battery; Critical Battery, Landing)
2Loss of C2 link + 10 seconds
(Set to risk)		HOV or HH; and GNSS; and
> 2m from launch position		– RTL then autoland
– GCS annunciations if C2 link re-established
< 2m from launch position– Autoland
3Nil GNSSSTAB or HH– GCS annunciation indicating NAV not available
NAV– Autoselects HH mode
– GCS annunciations
– Co-pilot recovers aircraft via hand controller to land in STAB
4GeofenceBreach– RTL then autoland
– GCS annunciations
Breach + 100 meters– Autoland
– GCS annunciations
Non-normal operations.

Example Flight Profile

Take-OffMissionLanding
Pilot Flying (PF)Co-Pilot:
– Gentle climb in STAB to visually establish aircraft outside ground effect to check control operation, then HH mode
– Position to vicinity of Take Off Rally and wait for authorisation from Captain to select NAV mode		Captain:
– NAV mode commands autopilot to navigate vehicle both laterally and vertically in accordance with Active Flight Plan, or as directed by specific command buttons on GCS		Captain:
– When Landing Rally has been sequenced as the active waypoint, the autopilot will navigate a pre-determined descent and landing profile
Pilot Monitoring
(PM)		Captain:
– Validate PFD/MFD information during climb (max 1 minute)
– Once (a) satisfied PFD/MFD checks out OK and (b) Captain is ready to take control, Co-Pilot can be advised that NAV mode may be selected  		Co-pilot:
– Watches vehicle throughout flight
– If undesired aircraft state observed, Co-pilot (as Pilot Monitoring) is authorised to immediately deselect NAV and take over to assure safe flight outcome
– Maintains situational awareness over operating environment (e.g. intruding aircraft, spectators, obstructions on runway, wind, weather etc)		Co-pilot:
– Watches vehicle throughout flight
– If undesired aircraft state observed, Co-pilot (as Pilot Monitoring) is authorised to immediately deselect NAV and take over to assure safe flight outcome
– Maintains situational awareness over operating environment (e.g. intruding aircraft, spectators, obstructions on runway, wind, weather etc)
Example of changes in pilot roles.

Hand-over/Take-over Procedure

What: The process of a pilot in command positively giving control of   the aircraft to another pilot or positively assuming   control from another pilot and the acknowledgement of this action by the pilot or co-pilot.

How:  Verbally

  • Handing Over – response: Taking Over
  • Taking Over – response: Handing Over

Captains:

  • If you authorise your Co-Pilot to select NAV mode, what you are implying is I’m happy and ready to take over.
  • Be watching out for your mode annunciation to change to NAV; your Co-pilot may not be able to fly and talk at the same time!
  • Acknowledge the NAV annunciation with Taking Over (and Handing Over if NAV changes to FBWA or UNAS)

Note:

  • A remote crew member can take control of the aircraft at any time should they believe an abnormal situation has arisen (legal implications may apply)!
  • If you are not ready or able to take over, withhold or rescind the NAV mode authorisation!

Summary

Covered Information:

  • Described the aerodynamic principles of multirotor flight and how multirotor aircraft attitude is controlled
  • Outlined considerations when Hovering In Ground Effect and operating in confined spaces
  • Outlined the normal and non-normal flight modes available for Academy multirotor flight operations