Aircraft and Crew Information
The aircraft involved was a Comco Ikarus C 42, registration HB-WAS, a single-engine, two-seat light aircraft with a fixed three-blade propeller. The owner and operator was Motorfluggruppe Obersimmental.
The crew consisted of a flight instructor (born 1966, Swiss) holding a Commercial Pilot License (CPL(A)) with 1,177 total flight hours, of which 78 hours were on type. The pilot (born 1960, German) held a Private Pilot License (PPL(A)) with 576 total hours, including 50 hours on type. Both had flown only 15 minutes in the previous 90 days on the accident aircraft.
Flight History
On 27 April 2015, the pilot and flight instructor met to conduct an annual proficiency flight, which included three circuits with simulated engine failures. After a pre-flight briefing, the pilot prepared the aircraft, noting approximately 25 liters of fuel and a wind from the north at 10–15 kt. The engine was warmed up for about 10 minutes; magneto checks were normal, but idle speed was 1700 RPM instead of the expected 1900 RPM.
The flight took off from runway 35 at about 15:30. After reaching a safe altitude of 3400 ft AMSL, the pilot accelerated and retracted flaps. The instructor then reduced the throttle to idle to simulate an engine failure. The pilot initiated a right turn back toward the airfield. During the turn, the aircraft sank more than expected. When the crew attempted to add power, the engine did not respond. The instructor took control but was unable to restore engine power. The aircraft struck treetops and came to rest in the Simme River.
Injuries and Damage
The aircraft was destroyed. The pilot sustained serious injuries; the flight instructor sustained minor injuries. There were no other occupants or fatalities. Minor ground damage occurred.
Probable Cause
The Swiss Transportation Safety Investigation Board (STSB) determined that the accident was due to collision with terrain resulting from an engine failure during a simulated engine failure exercise, followed by a return turn at too low an altitude.