What happened
On October 31, 2003, during the opening day of an air show at the Twin Ring Motegi Auto Race Circuit in Tochigi Prefecture, a Sukhoi Su-2t6, registration RA2821K, crashed while performing a precision maneuver. The aircraft, operated by the ASB Flying Club, was participating in a time challenge competition designed to test a pilot's ability to fly through specific gates and cut suspended tapes.
After successfully completing a standard flight through the first gate, the pilot attempted an inverted pass through the second gate. During this maneuver, the aircraft began to deviate from the intended course centerline. While attempting to maintain the flight path to complete the task, the aircraft entered a steep descent and drifted toward the left side of the course. At approximately 10:31 JST, the aircraft struck a floodlight stay and other obstacles, including a signal pole and a small observation building, before crashing into the ground. The pilot sustained serious injuries, and the aircraft was destroyed.
The investigation
Investigators analyzed video recordings and photographs provided by the event sponsors to reconstruct the flight path. The examination revealed that the aircraft entered the inverted portion of the course at an altitude of approximately 10 meters. Following the roll into inverted flight, the aircraft's right wing lowered, causing it to drift right, before the left wing lowered, causing a leftward deviation.
Technical analysis of the wreckage confirmed that the aircraft's left wing was severed at the root and the propeller blades were destroyed upon impact. The investigation also scrutinized the regulatory framework of the event, specifically looking at the flight permits issued under the Civil Aviation Law. It was determined that the specific maneuvers performed—flying at extremely low altitudes in inverted flight—did not align with the parameters of the aerobatic flight permits previously obtained by the organizers.
Findings
- The primary cause of the accident was the pilot's decision to continue the maneuver to cut the tape despite the aircraft deviating from the course. This focus on completing the task likely led to a momentary loss of situational awareness regarding the aircraft's attitude and position relative to ground obstacles.
- The aircraft was flying in a steep descent and a banked attitude, which made it impossible to avoid the floodlight stay once the deviation had begun.
- There was a regulatory discrepancy, as the organizers had not included the specific airspace requirements for the time challenge competition in their aerobatic flight applications, mistakenly classifying the event as an exhibition flight rather than an aerobatic one.
- The pilot's high level of skill and determination to succeed in front of a large audience contributed to the decision to pursue the task even when flight safety was compromised.