What happened
On July 13, 1990, at approximately 10:45 local time, a Cessna C-172 P with registration HB-CLC was involved in an accident at the Triengen airfield in Switzerland. The aircraft was operating under visual flight rules for a private recreational flight. The pilot had departed from Basel earlier that morning with three passengers aboard. The planned itinerary included stops over Burgdorf, Thun, the Brünig Pass, Buochs, Beckenried, and Lucerne.
The aircraft departed with fuel tanks half-full, providing an endurance of approximately two hours and thirty minutes against a planned flight time of one hour and thirty minutes. After flying for about one hour and twenty minutes over Lake Lucerne, the pilot determined that fuel reserves were becoming low and decided to make an unscheduled stop at Triengen.
The initial approach to Runway 33 was conducted from the west. The pilot reported that the base leg and final approach segments were flown too high, necessitating a go-around. After completing a shortened turn, the aircraft presented itself on the second approach slightly above the optimal glide path. The pilot estimated an approach speed of 75 knots on final and 70 knots on short final.
Witnesses observed the aircraft touch down approximately 30 meters past the runway threshold at a relatively high speed. According to the pilot's account, the aircraft bounced once, then lifted off again after about 50 meters. Despite braking, it bounced a second time. Realizing that remaining runway length was insufficient to stop, the pilot initiated a go-around in the last third of the runway. The stall warning sounded as the aircraft lifted off but failed to gain sufficient altitude, resulting in a collision with a wheat field located 118 meters beyond the end of the paved surface.
The main gear struck the field first, followed by the nose gear. The aircraft rolled for 42 meters before coming to rest on its back. All four occupants escaped without injury. The aircraft sustained severe damage, including a bent nose gear, a detached engine, deformed left wing, and compressed empennage.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined the flight data, witness statements, and wreckage. The pilot held a valid private pilot license and had logged 57 hours and 13 minutes of total flight time, with only 7 hours and 4 minutes in the preceding six months. The aircraft was airworthy, maintained according to regulations, and within weight and balance limits.
Weather conditions at the time were clear with visibility exceeding 10 kilometers, variable wind at 3 knots, and a temperature of 20°C. The investigation found no evidence of medical issues affecting the pilot or technical failures contributing to the accident. Post-accident fuel analysis indicated approximately 15 liters remained on board.
Findings
The primary cause of the accident was the aircraft exceeding its minimum lift speed during a go-around procedure that was initiated too late. Contributing factors included the pilot's limited flight experience and insufficient pre-flight preparation for the specific challenges of landing at Triengen, which has a short runway (395 meters) that can be problematic for a fully loaded Cessna 172.
The pilot's decision to force a second landing attempt after the first go-around led to excessive approach speed. This resulted in multiple bounces on the runway. The decision to abort the landing and climb out was made after the aircraft had already touched down and bounced, leaving insufficient time and altitude to recover from the subsequent stall.
Safety action
The investigation highlighted the risks associated with short runways for light aircraft carrying full loads. It emphasized the importance of adequate pre-flight planning regarding fuel reserves and runway performance calculations. The report noted that while the decision to divert for fuel was prudent, the execution of the landing at a constrained airfield required greater caution and adherence to safe approach speeds.