1997 Pulsar XP accident at Quinto, Piotta (HB-YHN)

Incident Overview and Flight Details On 16 November 1997, a privately owned and operated Pulsar XP, registration HB-YHN, was destroyed in a crash near Quinto, a fraction of Piotta in the canton of Ticino, Switzerland. The accident occurred at 1625 local time (UTC+1) during the climb phase after takeoff. The aircraft was on a private visual flight rules (VFR) flight from Ambrì to Wangen-Lachen. Both occupants, Pilot A and Pilot B, were killed. Pilot A, a Swiss citizen born in 1947, held a private pilot license and had a total of 240:36 flight hours, including 71:53 on the accident type. Pilot B, a Swiss citizen born in 1954, held an airline pilot license with approximately 3,535:40 total flight hours. Pilot B was seated in the right seat as a passenger. ## Accident Sequence and Observations The aircraft took off normally from runway 29 at Ambrì at 1621 local time with a good rate of climb. Witnesses observed the aircraft maintaining its route toward Airolo, entering the Stalvedro gorge. One witness reported seeing the aircraft pitch up and down twice on the transverse axis before deviating slightly to the right. Another witness from Airolo observed the aircraft making a left turn in the middle of the valley, which suddenly tightened. The aircraft was seen oscillating on the longitudinal and vertical axes, maintaining a southward heading while descending vertically in a constant and regular manner. The Pulsar XP struck the ground in a rotating phase with an incidence of approximately 20 degrees relative to the ground. The impact destroyed the aircraft and fatally injured both occupants. ## Investigation Findings and Technical Aspects The investigation found no evidence of physical impairment or alcohol involvement for either pilot. The aircraft's mass and center of gravity were within prescribed limits, though the mass was at the maximum allowable limit. Three-point seatbelts were used and withstood the impact. The emergency locator transmitter (ELT) functioned during the impact. Technical examinations by EMPA indicated no technical deficiency caused the accident. The propeller was likely still rotating at impact, though it could not be determined whether by engine power or windmilling. The fuel valve was found open, and the fuel filter was clean. The airspeed indicator was broken with the needle off scale, while the variometer indicated a descent of 1,400 ft/min. The investigation noted that the Pulsar XP kit had a difference in incidence angles between the right and left wings, and test flights showed it was easier to enter a right spin than a left one. The aircraft had two directional pedals but only one center-mounted control stick, making it practically impossible for the right-seat occupant to assume control. ## Operational and Meteorological Context Pilot A was not familiar with Ambrì aerodrome, having been there only about four times. The aerodrome is considered difficult due to its alpine location, narrow valley circuits, and mandatory axes for approach and takeoff. Pilot B, however, was very familiar with Ambrì and had completed several circuit flights in the hour before the accident. Meteorological data from the Piotta automatic station at the time of the accident showed 3-4/8th clouds with a base at 9,000 ft MSL, 20 km visibility, wind from 275 degrees at 12 knots with gusts to 22 knots, and a temperature of +09°C. The pressure was 1015 hPa/QNH. The investigation noted that north winds from the upper atmosphere descended from the Gotthard Pass and side valleys of the upper Leventina, creating wind shear and turbulence, particularly near the outflow of the Piora and Val Canaria valleys and the southern exit of the Gotthard Pass. The sun's position at the time had an azimuth of 238 degrees and an altitude of 4 degrees. The end of daylight was at 1728 local time, leaving the pilots little time margin to reach their destination before nightfall, given the 1621 takeoff and an estimated 40-minute flight time to Wangen-Lachen.