Air safety investigators are still unable to determine why the pilot of the Cirrus light aircraft which crashed in a Gundaroo paddock on October 6 killing all four people on board was unable to deploy the "last resort" parachute.
The Australian Transport Safety Bureau has released a preliminary report on the crash which found that the single-engined aircraft had "low or no power" at impact and that key components of the airframe parachute system were all located in the wreckage.
The report noted that "spin recovery, icing, un-porting of fuel tank outlets in a spin, preparation for use of the parachute, and an engine mechanical issue" could all be reasons for a reduction in engine power.
Investigators found that experienced pilot Peter Nally, 65, who was taking a return flight from Canberra to Armidale, in northern NSW, struck problems when the single-engined Cirrus SR22 was climbing to its planned cruising altitude of 10,000 feet about 25km from Canberra Airport.
On board were his three grandchildren: Raphael, 11, Evita, 9, and six-year-old Philomena Smith.
During the flight, data was being transmitted by the aircraft's Automatic Dependent Surveillance Broadcast (ADS-B) equipment.
All appeared to be as normal as the aircraft passed through 7500 feet with a relatively constant rate of climb and ground speed decreasing at a "linear rate".
But then as the aircraft passed through 8500 feet, it lost ground speed, then entered a slight descent and gained speed. Over the next four minutes, the aircraft's track varied up to 35 degrees and the groundspeed fluctuated between 90 and 120 knots (167-222kmh).
"Several people at locations below the aircraft's flight path during this time reported hearing noises that they described as a rough running or surging light aircraft engine," the ATSB report said.
"Witnesses described the aircraft rotating in a corkscrew motion," ATSB director of transport safety Kerri Hughes said.
Around 12 minutes after take-off "it abruptly departed from controlled flight and descended steeply toward the ground".
The aircraft struck the ground at a paddock just off Brooks Creek Lane outside Gundaroo in a terrific impact and burst into flame.
Flight conditions at the time included isolated rain showers, broken cumulus/stratocumulus cloud, and a freezing level of 5000 feet in the south and 8000 feet in the north, "conditions which can imply moderate turbulence and moderate icing".
"As the investigation continues, the ATSB will continue an assessment of the recovered components, review pilot and operator documentation and pilot medical information, and analysis of the aircraft's performance based on flight track data and meteorological information," Ms Hughes said.
The SR22 was built in the US 21 years ago and features a ballistic parachute which was serviced and replaced in January this year. The previous engine service was in November 2022.
The Cirrus operating handbook stated it was "not certified for spin recovery, [therefore] the Cirrus Airframe Parachute System (CAPS) must be deployed if the airplane departs controlled flight".
The Cirrus Owners and Pilots Association reported there had been 145 CAPS deployments up to July 13 this year, of which 120 had been listed as "saves".
The three children from Armidale had been on a visit to Canberra, including going to the National Zoo and Aquarium. They had been returning home to Armidale when the crash occurred.
