What happened
On April 17, 2017, at 11:04 UTC, a private Piper PA-3/1T Cheyenne II, registration HB-LTI, departed from runway 17 of the Cascais aerodrome (LPCS) bound for Marseille (LFML). The aircraft was carrying a crew of one pilot and three passengers.
Following takeoff, air traffic control instructed the aircraft to turn right, intercept, and maintain radial 230 from the Cascais VOR while climbing to 3,000 feet. According to eyewitness accounts, the aircraft began to bank heavily to the left while climbing slowly to approximately 300 feet. As the aircraft's speed decreased, it entered a stall, leading to a steep descent. The aircraft impacted a supermarket truck unloading dock approximately 700 meters from the end of the departure runway.
The impact caused the aircraft to explode and catch fire, which also ignited a truck parked at the site. The impact and subsequent fire resulted in the four fatalities of all occupants on board the aircraft. The driver of the truck was also killed by the explosion.
The investigation
The GPIAAF investigation team was dispatched to the scene shortly after the occurrence. The investigation focused on the sequence of events following takeoff and the circumstances leading to the loss of control. Meteorological conditions at the time were reported as having a wind of 220 degrees at 05 knots, a temperature of 22°C, a QNH of 1014 hPa, and visibility exceeding 10 km.