Jämijärvi air crash

Investigation

Jämijärvi aerodrome, near which the aircraft fell, is one of the largest parachuting sport centres in Finland. All the aircraft's passengers were members of an aviation club from Tampere. The Comp Air 8 turboprop aircraft had been built by them themselves, and all the licences related to the flights were valid. The aircraft received its operating licence in August 2009. The aircraft was last inspected in 2012. According to a statement by the Finnish Aeronautical Association, this aircraft «was the largest aircraft in the country built by amateurs».

According to preliminary data, the most likely cause of the air crash was problems with controlling the aircraft. There was a supposition that the aircraft had suffered a wing failure in flight, which could have been caused by overloading or by a design flaw.

Ismo Aaltonen was appointed head of the investigation into the aviation accident. According to him, the control problems that arose led to the aircraft entering a spin and striking the ground at high speed. Aaltonen reported that the three survivors were able to jump out of the aircraft through the front door, whereas the jump hatch was closed.

On 25 April it was announced that the Safety Investigation Authority had completed its investigative work at the crash site and the preliminary investigation; the cause of what happened, however, had not been established. The pilot told the investigation that at an altitude of about 4 km the aircraft had developed problems with longitudinal stability; the aircraft entered an inverted spin and after approximately one minute fell sideways to the ground. During the fall, the aircraft's wing cracked (but did not come off, as had been reported earlier).

According to the Safety Investigation Authority, one of the causes of the crash of the aircraft carrying parachutists was the failure of the support strut of the right wing, which occurred as a result of an error in controlling the aircraft. At the same time, as the technical examination showed, the crack in the wing support had existed even before the aircraft crashed, but it could not have been noticed during a standard pre-flight inspection.

In April 2015 the Safety Investigation Authority published a report on the investigation carried out, according to which the accident was caused both by structural failures and by violations in the operation of the aircraft, with the direct cause of the accident being the failure of the support strut of the aircraft's right wing.