Review of midair collisions involving general aviation ... - Fly Safe!

There were also five collisions that occurred near the circuit area (that is, within 5 NM
of an airport and with at least one aircraft arriving at, or departing from, that airport).
These included one aeroplane-aeroplane collision at 1,500 ft with both aircraft on
departure, one aeroplane-helicopter collision at about 1,500-2,000 ft with both aircraft
on arrival, and three aeroplane-glider collisions at less than 2,000 ft with the
aeroplane climbing.
Of the 20 aeroplane-aeroplane collisions that occurred in or near the circuit area, 25
aeroplanes were on training flights, 12 were on private flights, two were on passenger
charter flights, and one was on an aerial work flight. At least 21 of the aeroplanes
were being used for circuit training or practice. The aeroplane-helicopter collision
involved two aircraft on aerial work flights, and the aeroplane-ultralight collision
involved two aircraft on private flights. The seven aeroplane-glider collisions
involved five aeroplanes being used as glider tugs, although only one was actually
towing a glider at or just prior to the accident. The other two aeroplanes were engaged
in private and aerial work operations.
Fifteen of the collisions in or near the circuit area occurred at one of the five major
general aviation airports; that is, Archerfield, Bankstown, Jandakot, Parafield or
Moorabbin. Thirteen of these collisions occurred during tower operating hours 7 ,
although in one of these collisions neither pilot had yet contacted the tower
(Moorabbin, 1970). Of the other two collisions, one (Jandakot, 2002) occurred just
after the tower controllers had handed over to an air ground operator. The other
collision (Moorabbin, 2002) occurred at night when the control zone was classified as
a mandatory broadcast zone (MBZ). No other collisions have occurred in MBZs in
Australia, which commenced in 1991.
Most (10) of the 15 collisions at the major general aviation airports occurred prior to
the introduction of General Aviation Aerodrome Procedures (GAAP) during tower
hours in 1980. 8 The major change to operations at these airports in 1980 was the
introduction of simultaneous contra-rotating circuit operations onto parallel runways
(contra-circuits) at those airports with parallel runways. The previous procedures
(known as a secondary control zone) involved all aircraft flying circuits in the same
direction on the same side of the runways. Due to the high aircraft movement rates,
tower controllers were only required to provide a limited service at secondary/GAAP
airports, with aircraft separation being primarily a pilot responsibility. A review of the
10 collisions that occurred prior to 1980 found that many of them were unlikely to
have occurred if contra-circuit operations to parallel runways had been in use.
Only one of the 37 collisions occurred in controlled airspace where air traffic services
were providing a full control service. This collision occurred in the Coolangatta
primary control zone in May 1988.
There were six collisions involving pilots deliberately flying close to another aircraft.
All were aeroplane-aeroplane collisions, and four involved formation flying activities.
7 Due to the high movement rates and the types of operations at these airports during tower hours, tower controllers were only
required to provide a limited service. Aircraft separation was primarily a pilot responsibility.
8 GAAP commenced at Parafield in 1978 and at the other five airports during 1980. The level of air traffic control service was
similar both before and after the introduction of GAAP.
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