L2014-01 Experimental aircraft accident and risk of explosion at Nummela aerodrome on 27 March 2014

A two-seat wood-structured Jodel D18 aircraft, registration OH-XAC, which the pilot had built himself for his private use took off for a test flight from Nummela aerodrome on Thursday 27 March, 2014 at 13.49. During the climb the aircraft made a sharp turn which resulted in a stall and a collision with the ground. One pilot perished and the other was seriously injured. The aircraft was destroyed. The cause of the accident was a turn at low altitude and at a low airspeed. It is possible that the flight crew made the turn in an attempt to avoid hitting an imagined towing line of a paraglider. The practice that the pilots had adopted, i.e. climbing at a low airspeed in a clean configuration and making a turn at low altitude, is a factor which subjected them to the accident. Insufficient coordination between operators at an uncontrolled aerodrome was a contributing factor. The fact that flight activity was taking place on a runway which was reported closed can also be regarded as a contributing factor.

The aircraft was fitted with a pyrotechnical, ballistic parachute system, the rocket motor of which caused a risk of ignition during the rescue operation. The investigation specifically focused on how a rescue operation can be conducted in a safe manner if the accident aircraft is fitted with a recovery parachute. In the case at Nummela the markings warning of the presence of a recovery parachute were not clearly identifiable, nor did the rescue personnel realise that they were subjected to the risk of explosion. The investigation determined that the rescue sector is not aware of pyrotechnical systems in general aviation or sport aviation, and that virtually no related training or regulations exist.

Moreover, there are foreign aircraft flying in Finland whose pyrotechnical system markings either differ from those used in Finland or are completely absent. In addition, incorrectly installed systems have been discovered abroad. The present aircraft register does not indicate whether an aircraft is fitted with a rocket-propelled ballistic recovery system. The presence of any such system can only be established by inspecting the aircraft on site.

On the basis of the investigation seven safety recommendations were issued.

Finnish Transport Safety Agency:

• Add information about the aircraft’s pyrotechnical systems into the aircraft register, define the minimum requirements for the safe installation, use and storage of such systems and make thermal exposure indicators compulsory for them.
• Also give attention to pyrotechnical systems installed in aircraft, including any potential hazards to rescue operations, in aerodrome maintenance regulations, and
• Recommend that operators of uncontrolled aerodromes update any of their own rescue plans, together with the local rescue authority.

European Aviation Safety Agency (EASA):

• Harmonise the markings of pyrotechnical systems and add a system-related segment into LAPL(A) and PPL (A) curricula.

International Civil Aviation Organization (ICAO):

• Standardise the colours of pyrotechnical system parts so that they are clearly distinguishable and easily identifiable.
  
  
  L2014-01 report (pdf, 1.52 Mt)