History
The pilot held a Private Pilot Licence (PPL(A)) issued by the Federal Office of Civil Aviation (FOCA) under EASA. After renewing his single-engine piston class rating in June 2016, he did not fly for two years. In June 2018, he completed the required flight training on a Cessna 152 for the next renewal, followed by another two-year break. In June 2020, he underwent familiarisation on the Mooney M20J, consisting of three flight hours and seven landings on the accident aircraft HB-DFK during a single afternoon. Subsequently, he conducted two additional flights, both local circuits in the same aircraft.
Accident Sequence
On 11 June 2020 at 10:06, the pilot departed from Runway 06 at Grenchen Airport (LSZG). After a 30-minute local flight, he contacted the control tower and received clearance for a straight-in approach to Runway 06, along with a wind report of 5 knots from 080 degrees. At 10:51, the aircraft touched down on the runway and became airborne again. This sequence repeated several times with increasingly hard touchdowns. After landing, the pilot taxied to the hangar and discovered damage to the propeller and nose gear. The damage was only noticed after landing.
Meteorological Conditions
Weather at Grenchen was fair with light winds. Shortly before the accident, the following conditions were observed: wind 4 knots from 070 degrees, visibility 10 km or more, clouds 1/8–2/8 at 2000 ft and 3/8–4/8 at 3900 ft above aerodrome reference height, temperature 17°C, dew point 12°C, QNH 1009 hPa.
Aircraft Information
The aircraft was a Mooney M20J, registered HB-DFK, owned and operated by Farner Aviation AG. The pilot had a total of 340:58 flight hours, with 6:04 hours on type, all within the last 90 days.
Analysis and Findings
The final approach followed a 3° glide path. Ground speed decreased continuously, with 76 kt at 50 ft above ground and 63 kt over the runway threshold. Calculated indicated airspeed was 81 KIAS at 50 ft and 68 KIAS at the threshold. The aircraft flight manual specifies an approach speed of 71 KIAS for a normal landing at maximum landing weight (2740 lb). For the actual weight of 2300 lb, later manual editions specify 65 KIAS for a normal landing. The pilot's speed was therefore above the recommended value.
The manual requires a "main wheels first" touchdown. The aircraft's design, with compact rubber shock disks, makes it prone to pitch oscillations if the nose gear touches down hard. During the landing, the initial touchdown resulted in a bounce. The pilot's elevator inputs caused a pilot-induced oscillation (porpoising). With each subsequent touchdown, the nose gear impacted harder, eventually leading to at least one propeller strike and damage to the nose gear.
The pilot's low recent flight training (no flying in the two years before the familiarisation) likely meant the brief familiarisation was insufficient to achieve the proficiency needed for this demanding aircraft type. This may have contributed to the decision not to execute a go-around.
The accident occurred because the aircraft touched down with excessive speed in an inappropriate attitude, leading to bouncing and porpoising. The pilot's limited recent training may have been a contributing factor.