Avoiding future G.A. mid-air collisions

Stephen Andrews | 15th January 2009 | Aviation | No Comments »

Civilian mid air collisions are not only occurring on an ever more frequent basis, but are wholly avoidable when aircraft are fitted with low-cost collision advisory equipment. Moreover, it is alarming that there is no apparent sense of urgency from the Civil Aviation Safety Authority (CASA) to address the problem permanently. With a rise in the density of General Aviation (GA) traffic accessing GAAP Aerodromes, it is now critical to review the required balance between appropriate airspace handling procedures and the need for mandatory onboard collision detection equipment.

Two separate incidents since July 2008 highlight this issue within the Australian general aviation industry; one near Sydney’s Bankstown GAAP Zone (Dec 08) and one at Melbourne’s Moorabbin GAAP Zone (Aug 08). A young flight instructor and two student pilots have lost their lives due to the crashes.

There have been comments that the prescribed general aviation airspace procedures are dangerous and are to blame for these deaths. It is true that significant reform has been seen over the last decade which decreases traffic interaction with air traffic control (ATC). Much more responsibility has been handed to the pilot in command to manage and follow their own flights unaided. If an aircraft is navigating visually outside of controlled airspace, it is essentially left to its own devices.

With respect to the Bankstown collision, concern has been expressed over the need for aircraft to report their inbound intentions at a certain fixed point outside the GAAP aerodrome (a VFR Approach Point). This simplifies and expedites the movement of traffic through the control zone itself. Concerns such as these are understandable as all aircraft wishing to enter the GAAP zone must fly to one of only 2-4 fixed points (depending on the aerodrome), are required to be at the same altitude and due to the fact that the airspace is uncontrolled the only means of separation is by sight. It is only once they reach one of these approach positions that ATC provides any kind of immediate traffic advice to the pilots. However, there are a number of reasons why this procedure should remain in force.

Due to the fact that GAAP zones are invariably placed in capital cities and thus near traffic-dense commercial/military airports, there is a need to control the flow of GA activity around these centres. One must also bear in mind the fact that a grand proportion of movement associated with GA facilities is of a flight training nature. Allowing traffic to approach a training aerodrome from any direction is confusing for a student pilot whose mind is occupied by an overwhelming number of new tasks. The insertion of aircraft though approach points provides GAAP ATC with the ability to allow circuit insertion in a generally consistent, predictable and therefore safe manner. It is the provision of information to pilots regarding separation at these approach points that requires attention.

With a sharp increase in the reliability of contemporary computer technology, civil aviation has been rapidly dragged into the 21st century. New aircraft are fitted with glass cockpits, terrain warning systems, digitalised engine monitoring, sophisticated flight management software and even airframe parachutes. In an industry where safety must be the paramount priority, it is no longer acceptable to simply specify a VHF radio and a transponder as the only communicative equipment required to legally enter controlled airspace.

Cockpit mounted Traffic Collision Avoidance Systems (TCAS) which would have averted both the Bankstown and Moorabbin incidents are now readily available. More importantly, despite common misconceptions about this type of instrumentation, they are incredibly affordable. These systems sense the transponder signals of aircraft in their vicinity and operate completely independent of ground based stations. Lower end systems simply provide a distance and relative altitude to nearby aircraft. Most importantly however, is that an auditory warning signal is fed to the pilot if a collision threat exists. Enough time is provided to allow for a change in flight level, and also to establish communication with ATC or the other aircraft so that the situation can be resolved in an informed and thus effective manner. While there are packages incorporating larger radar-style displays (costing USD$10,000-30,000), that level of detail is not needed for GA operations.

The following style of equipment is cost effective, simple and necessary to avoid further mid incidents (For information on higher end systems, see manufacturers such as Garmin, Avidyne & Honeywell):

After numerous large scale commercial mid air accidents, it took the deaths of 82 people in 1986 to spur the US and the rest of the world to mandate the carriage of TCAS in larger commercial aircraft. The same philosophy must now be applied to all aircraft wishing to operate in or around any form of controlled airspace. Indeed it would be simpler to apply a blanket regulation to any aeronautical craft operating in Australian airspace.

In the last 6 months, three people have been killed by these avoidable collisions in Australia alone. How many more need to occur before something is done? Next time, there will be no excuse.