Norwegian investigators are recommending greater emphasis on spin prevention and recovery for flight instructors, after a fatal accident involving a Diamond Aircraft DA42 NG during a pilot-training exercise.
Two students from Oslo Torp-based Pilot Flight Academy – one under instruction, and one observing from the rear seat – had been on board with an instructor when the aircraft came down in woodland on 23 November 2021. None of the three survived.
Fire destroyed the wreckage and prevented investigation authority SHK from extracting any stored electronic data, limiting the inquiry’s ability to determine the circumstances of the accident.
SHK says the DA42 entered a spin, some 32min into the flight, but found no failures with the aircraft which could explain the event, and weather conditions were good.
The aircraft had been undertaking slow-speed flight, with the landing-gear and flaps extended, at a height of 3,600ft some 8km west of Larvik.
SHK says the flight was the student’s first instruction flight in a twin-engined aircraft, although he had recorded 18h in a DA42 simulator.
The inquiry could not determine whether the instructor or student was flying the aircraft at the time control was lost.
But SHK points out that the instructor is “meant to constitute a safety barrier”, even if a student is the flying pilot.
As the DA42 was performing a third slow-flight pass, its speed gradually declined from 123kt to 65kt, and it began rolling 7° to the left. While little accurate data is available, there is evidence it entered a right-hand spin with a descent rate reaching 8,000ft/min.
SHK found that the instructor had received only 45min of flight training, on top of theoretical work, relating to stalls and spins.
It believes that these levels of theoretical and practical training “do not provide a sufficient basis” for preventing a spin, emphasising that the need for rapid intervention means the skills required to recognise and exit a spin must become instinctive.
“There are no requirements for practical refresher training for instructors in spin prevention and spin recovery,” it adds.
SHK has examined other similar events involving the DA42, including a non-fatal spin and crash into woodland during an instruction flight in Sweden in January 2016.
This aircraft had also been carrying an instructor and two students – one in the rear – and the inquiry points out that flight characteristics of aircraft, including the DA42, become “more demanding” with respect to stalling and spinning when the centre-of-gravity is closer to the aft limit.
SHK says a flight-training instructor in Sweden detailed two DA42 spin incidents to the Norwegian investigation upon learning that three people had been in the aircraft that crashed near Larvik.
Only two people – the instructor and a student – had been on board when the first incident occurred, in August 2019. It happened during a simulated go-around with single-engine failure at 5,200ft, when the student pressed the wrong rudder pedal. The instructor recovered by using full rudder-pedal force and “kicking” the rudder to oppose the spin.
But the second incident, during a similar exercise in March 2021, was more serious. This time the aircraft had three occupants, including a second student in the rear seat, when it entered the spin. SHK says the aircraft rotated violently, and descended rapidly, and the instructor experienced significant difficulty in trying to recover. It ultimately stopped spinning without his understanding why, and control was regained only about 500ft above ground.
SHK says one of the students withdrew from the pilot-training programme after the incident, while the instructor was given time off. He described the second incident as being substantially more “brutal” than the first, and believed this might have been due to the aircraft’s having three people on board.
Weight-and-balance documentation for the aircraft which crashed near Larvik could not be located, and the inquiry assumes it was taken onto the aircraft instead of being left at the training school.
Immediately after the DA42 accident, Pilot Flight Academy prohibited the carriage of passengers in the rear seat during instruction flights. It subsequently lifted this ban, in favour of imposing centre-of-gravity limits for certain exercises, including slow flight and stall training – limits which effectively prevent passenger carriage in any respect.
SHK says the academy also conducted an extensive review of its activities, and took several steps to improve safety, including extending lesson-preparation time, raising the lower speed limit for slow-flight exercises, and revising procedures.