A Cessna 182G was climbing to 10,000 ft for a parachute drop
over the Warnervale authorised landing area (ALA) while a Twin
Otter was operating a regular public transport flight from
Aeropelican to Sydney at 6,000 ft outside controlled airspace
(OCTA). The airspace above Warnervale ALA was Class G up to 7,500
ft, including a common traffic advisory frequency (CTAF) from
ground level to 3,000 ft, and Class C above 7,500 ft.
While climbing OCTA, the Cessna pilot broadcast his intentions
on the CTAF and area frequencies, but received no replies. When the
pilot called Sydney Departures for clearance into Class C airspace
above 7,500 ft, the controller advised him of the Twin Otter in his
vicinity. The controller then cleared the Cessna to enter the CTA
and cleared it to carry out the parachute drop.
Immediately after releasing the parachutists about 1.5 miles
west of the drop zone, the Cessna pilot looked back and saw the
Twin Otter just south of the drop zone on a southerly heading. He
then called the Twin Otter crew and asked if they had seen the
parachutes. The Twin Otter crew replied that they had not seen the
parachutes and had no prior warning of the drop. The parachutists
later reported that they did not see the Twin Otter. The minimum
separation between the Twin Otter and the parachutists was
estimated to be 1 NM.
Procedures governing parachuting operations from Class C
airspace are detailed in AIP OPS SPEC-8 para 95.2.which states;
95.2.2 Where parachutists will leave classes B, C or D airspace
on descent, the pilot of the aircraft must broadcast the intention
to drop, at least two (2) minutes prior to exit, on the relevant
CTAF, Area VHF or MBZ frequency. Notwithstanding that a drop
clearance may have been issued, the drop must not proceed if
replies to this broadcast (or visual observation) indicate that
there is conflicting traffic beneath the CTA. The drop must not
proceed until the conflicting traffic is clear.
The controller advised the Cessna pilot of other aircraft in the
vicinity of the drop zone in accordance with the AIP requirements.
Although aware of the presence of the Twin Otter below, the Cessna
pilot did not ensure that the Twin Otter was clear of the drop zone
before releasing the parachutists.