What happened
On August 15, 2008, a Piper PA-28R-200 Arrow II, registration OH-PDY, crashed into the southern tip of Peräluoto island in Lake Saimaa, near Lappeenranta, Finland. The aircraft, operated by Patria Pilot Training Oy, was conducting an instrument training flight from Helsinki-Malmi to Kuopio, with a subsequent check flight (VTL) toward Lappeenrant.
During the flight, the pilot requested permission to descend from 8,000 ft to 3,000 ft to perform maneuvers involving recoveries from unusual attitudes. During these maneuvers, the aircraft experienced an extreme increase in airspeed and structural loading. The aircraft's wings detached from the fuselage, and the aircraft plummeted into the water. The impact resulted in three fatalities, including the flight instructor and two flight students.
The investigation
Investigators examined wreckage recovered from the lake, noting that approximately half of both wings and the right side of the horizontal stabilizer were missing. Technical analysis of the wing spars and stabilizer components by the VTT Technical Research Centre found no evidence of metal fatigue or material defects.
Because the aircraft lacked a Flight Data Recorder (FDR) and the installed GPS lacked a track-log function, investigators utilized radar data to reconstruct the final two minutes of the flight. Mathematical modeling of the flight path indicated that for the wings to have failed, the airspeed must have reached at least 155 knots, subjecting the airframe to a load factor of approximately 7g.
Findings
- The immediate cause was the instructor's decision to maneuver the aircraft into an unusual attitude that left no margin for error during recovery.
- The instructor likely overestimated both their own ability to correct student errors and the student's ability to execute the recovery.
- High-speed control inputs during the recovery process caused the excessive acceleration that led to structural failure.
- A significant contributing factor was the lack of familiarity with the specific aircraft type; the instructor had performed this specific maneuver series only once previously on this model, and the student had never practiced it on this aircraft type.
- Organizational issues, including inconsistent instructor training, lack of detailed procedures for check flights, and schedule pressures due to high student numbers, contributed to the unsafe flight environment.