What happened
On July 5, 1989, a Robin DR 400/180, registration HB-KAI, was conducting touch-and-go training operations at Mulhouse-Habsheim aerodrome in France. The pilot in command, seated on the left, was undergoing initial training on this specific aircraft type. He was accompanied by an experienced pilot seated on the right, who likely served as an instructor despite lacking current instructional qualifications.
Approximately 12:40 local time, the aircraft completed its fifth touch-and-go on runway 024. After rolling briefly on the ground, it took off again and climbed to an altitude of 60 to 90 meters above the terrain. The pilot then executed a sharp right turn with a bank angle estimated between 60 and 80 degrees. The aircraft stalled, rolled onto its side, and crashed into the Hardt forest. It struck a large oak tree at an approximate angle of 40 degrees before coming to rest. Both occupants were killed instantly, and the aircraft was destroyed.
The investigation
The Bureau d'Enquêtes sur les Accidents de l'Aviation Civile (BEA) conducted the investigation. Examination of the wreckage revealed that the wings had been torn off and remained caught in the trees. The cockpit was completely shattered. Analysis of the propeller indicated it was rotating at low speed without engine power at impact, consistent with windmilling.
Engine teardown showed no internal anomalies that would explain an in-flight shutdown prior to impact. The cylinder number 2 piston rod was broken due to the impact forces. The carburetor throttle linkage was broken, likely from the crash impact, making it impossible to determine the throttle position before the accident. The ignition key was found broken in the 'L' (left magneto) position, but its state at impact could not be definitively established.
Fuel flow appeared adequate as the fuel valve was open and fuel was present in the carburetor intake line, though the carburetor body itself was dry due to venturi suction. The electric fuel pump was off, and the battery and alternator switches were cut. The engine crankshaft turned with difficulty, indicating damage from the crash rather than pre-impact failure.
Findings
The investigation concluded that the probable cause was loss of control during a steep turn at low speed and low altitude, following a loss of power during climb. Key contributing factors included:
- Pilot Experience: The pilot in command had only 35 hours on the DR 400 type and had not flown since June 1988.
- Instructor Qualification: The passenger, while highly experienced with 35,500 total flight hours, did not hold a current instructor qualification.
- Aerodynamic Stall: The aircraft entered a stall during a tight turn at low altitude, leaving insufficient time or height to recover.
No mechanical failure was identified as the primary cause. The engine appeared capable of producing power, and no pre-existing defects were found that would have caused an immediate shutdown.
Safety action
The report highlighted the discrepancy between the passenger's extensive experience and his lack of current instructional certification. It also noted the pilot's limited recent experience on the specific aircraft type. No further safety recommendations or actions were recorded in this specific document beyond the factual findings.