Operate & Manage – Collision Avoidance & Automated Systems

Operate & Manage – Collision Avoidance & Automated Systems

Class Discussion
  • Is it possible to detect and avoid other aircraft in flight?
  • Is it possible to detect and avoid collision with terrain?
  • If so how can these be accomplished?
Collision Avoidance Systems

Modern aircraft and RPAS often use several collision avoidance systems to prevent:

  • Ground collisions
  • Aircraft collisions
  • Obstacle collisions

Radar Systems

  • Airborne radar:
    • Airborne radar can detect the relative location of other aircraft, and has been in military use since World War II
    • It was introduced to help night fighters (such as the de Havilland Mosquito and Messerschmitt Bf 110) locate bombers.
    • While larger civil aircraft carry weather radar, sensitive anti-collision radar is rare in non-military aircraft
  • GPWS:
    • Ground proximity warning system (GPWS), or Ground Collision Warning System (GCWS)
    • Uses a radar altimeter to detect proximity to the ground or unusual descent rates
    • GPWS is common on civil airliners and larger general aviation aircraft

Transponder-Based

  • TCAS:
    • Traffic Collision Avoidance System (TCAS) actively interrogates the transponders of other aircraft and negotiates collision-avoidance tactics with them in case of a threat.
    • TCAS systems are relatively expensive, and tend to appear only on larger aircraft. They are effective in avoiding collisions only with other aircraft that are equipped with functioning transponders with altitude reporting.
    • It is a type of airborne collision avoidance system mandated by the International Civil Aviation Organization to be fitted to all aircraft with a maximum take-off mass (MTOM) of over 5,700 kg (12,600 lb) or authorized to carry more than 19 passengers.
    • ACAS/TCAS is based on secondary surveillance radar (SSR) transponder signals, but operates independently of ground-based equipment to provide advice to the pilot on potentially conflicting aircraft.
  • PCAS:
    • A Portable Collision Avoidance System (PCAS) is a less expensive, passive version of TCAS designed for general aviation use.
    • PCAS systems do not actively interrogate the transponders of other aircraft, but listen passively to responses from other interrogations. PCAS is subject to the same limitations as TCAS, although the cost for PCAS is significantly less.

GPS-Based

  • FLARM:
    • FLARM is a small-size, low-power device (commonly used in gliders or other light aircraft) which broadcasts its own position and speed vector (as obtained with an integrated GPS) over a license-free ISM band radio transmission.
    • At the same time it listens to other devices based on the same standard.
    • Intelligent motion prediction algorithms predict short-term conflicts and warn the pilot accordingly by acoustical and visual means.
    • FLARM incorporates a high-precision WAAS 16-channel GPS receiver and an integrated low-power radio transceiver. Static obstacles are included in FLARM’s database. No warning is given if an aircraft does not contain an additional FLARM device.
  • TAWS:
    • A Terrain awareness and warning system (TAWS) uses a digital terrain map, together with position information from a navigation system such as GPS, to predict whether the aircraft’s current flight path could put it in conflict with obstacles such as mountains or high towers, that would not be detected by GPWS (which uses the ground elevation directly beneath the aircraft).
    • One of the best examples of this type of technology is the Auto-GCAS (Ground Collision Avoidance System) and PARS (Pilot Activated Recovery System) that was installed on the entire USAF fleet of F-16’s in 2014.

Visual Systems

  • Synthetic Vision:
    • Synthetic vision provides pilots with a computer-generated simulation of their outside environment for use in low or zero-visibility situations.
    • Information used to present warnings is often taken from Global Positioning System (GPS), Internal Navigation Systems (INS), or gyroscopic sensors
  • Visual Positioning:
    • Uses camera systems to detect upcoming obstacles
    • Requires significant processing power on-board the aircraft to perform the detection
    • Very new technology; it is not flight-proven and is only available in some state-of-the-art RPAS systems
Limitations of Automated Systems

Class Discussion Topic:

  • Is a highly automated aircraft a bonus or a problem to the aviation industry?
  • At what point does automation become autonomy?
  • Would autonomous aircraft be more of a bonus or problem?

Advantages to Automation:

  • Increased capacity and productivity
  • More precise handling of routine
  • Human benefit:
    • Decreased mental workload
    • Reduction of manual workload and fatigue
    • Relief from routine operations
    • Lower operator proficiency requirements
  • System accuracy:
    • Higher accuracy
    • Smaller tolerances
    • Relief from small errors

Disadvantages to Automation:

  • Dehumanizing and lower job satisfaction
  • Automation-induced failures:
    • Low alertness of human operators
    • Loss of operator proficiency for manual takeover
    • Over-reliance
    • Complacency
    • Willingness to uncritically accept results
  • Edge cases:
    • False alarms
    • Silent failures
    • Systems are fault intolerant, issues may compound