The pilot of the Cessna 172R had planned a private flight, with three friends, from Moorabbin via Williamstown, Laverton, Melton and Torquay before returning to Moorabbin. Before departure, the pilot arranged for the fuel load on the aircraft to be adjusted in order to ensure that the aircraft did not exceed its maximum allowable weight limit. The aircraft departed Moorabbin at about 1350 Eastern Summer Time.
Witnesses, including some with relevant aviation experience, reported seeing the aircraft conducting steep turns south of Melton township, north-east of Melton aerodrome, north of Gisborne and in the vicinity of the accident site. This information is consistent with photographs taken from the aircraft during the flight.
Radar information indicated that between 1432 and 1435, the aircraft was flown in a sequence of left turns through 360 degrees in the vicinity of the accident site. These turns were conducted at an altitude of between 1,900 ft and 2,300 ft above mean sea level (approximately 550 to 950 ft above ground level).
Witnesses reported that after completing two 360 degree left turns in the vicinity of the accident site, the aircraft headed north and adopted a nose-high attitude before entering a steep turn to the left. Most of the witnesses, including an experienced pilot, described seeing the aircraft's bank angle steepen as it passed a westerly heading and then the nose dropped such that the aircraft was heading approximately south in a near vertical, nose-down attitude. However, one witness described seeing the aircraft roll in a right-wing-over-left manoeuvre before it pitched nose-down.
One witness reported seeing the aircraft spiral to the ground however most witnesses saw it descend straight to the ground in a nose-down, near vertical attitude. Witness reports and wreckage evidence indicated that the aircraft impacted the ground heading approximately south and in a nose-down, right wing low attitude. The aircraft, which was destroyed by the impact, came to rest approximately 27 m from the initial impact point. There was no fire. The occupants received fatal injuries.
The wreckage was located in a paddock approximately 400 m north of the Gisborne-Kilmore Road, approximately half-way between Gisborne and Riddells Creek. The residence of one of the passengers was less than 1 km from the accident site. The elevation of the accident site was about 1,350 ft and Mount Macedon (3,284 ft) was 11 km to the north-north-west. The damage indicated that the engine was producing power and that the flaps were extended to approximately 10 degrees at the time of impact. The investigation did not identify any pre-existing defects that could have affected the operation of the aircraft.
Coordinated use of aileron, elevator and rudder controls will ensure that an aircraft maintains balanced flight. Discussions with the US Federal Aviation Authority (FAA) indicated that the Cessna 172 aircraft will exhibit mild stall characteristics if the aircraft stalls during balanced flight, and a pilot can regain control of the aircraft with a minimal loss of height. Most aircraft would require significantly more height above the ground to allow a pilot to recover control following a stall during unbalanced flight.
The Cessna Integrated Flight Training System Manual of Flight stated that a stall during a steep turn will result in a sharp nose and wing drop and that recovery actions must be prompt and precise.
The pilot held a private pilot licence and was endorsed on the aircraft type. He had completed spin recovery training, however the training was conducted in a different aircraft type. The pilot had accrued approximately 68 hours total flying experience. The post-mortem and toxicological examination did not identify any pre-existing conditions that could have affected the pilot's ability to fly the aircraft.
At the time of the accident the prevailing weather conditions were fine with scattered high level cloud. The Kilmore Gap automatic weather observation taken at 1430 indicated that the wind was 340 degrees at 19 kts gusting to 27 kts. The observation taken at Melbourne's Tullamarine airport at 1431 indicated that the wind was 360 degrees at 15 kts gusting to 27 kts and that the temperature was 33 degrees Celcius. During strong, gusting wind conditions such as existed at the time of the accident, hills and mountains can induce severe turbulence and downdraughts.
The aircraft was probably operating in turbulent conditions at the time of the accident, given the location of Mount Macedon upwind of the accident site. The manoeuvre described by witnesses was consistent with the aircraft stalling during the steep left turn. It is likely that the aircraft's reduced performance in the ambient temperature and the gusty and turbulent conditions contributed to the stall. In addition, the turbulent conditions would have made it very difficult for the pilot to maintain the aircraft in balanced flight during the sequence of steep turns. The loss of control following the stall and the pilot's failure to recover control in the height available was consistent with the stall occurring during unbalanced flight.
|Date:||01 December 1999||Investigation status:||Completed|
|Time:||1434 hours ESuT|
|Location:||6 km NE Gisborne|
|State:||Victoria||Occurrence type:||Loss of control|
|Release date:||05 April 2000||Occurrence class:||Operational|
|Report status:||Final||Occurrence category:||Accident|
|Highest injury level:||Fatal|
|Aircraft manufacturer||Cessna Aircraft Company|
|Type of operation||Private|
|Damage to aircraft||Destroyed|
|Departure point||Moorabbin, VIC|
|Role||Class of licence||Hours on type||Hours total|