History of the Flight
The flight from Kägiswil (LSPG) to Valencia, Spain was planned about two months earlier. On the day before the accident, the pilot submitted customs declarations for the three occupants. That evening, the pilot and passengers had dinner; the pilot did not consume alcohol. The planned flight and weather were discussed.
On the morning of 27 August 2013, the pilot checked weather forecasts and decided to depart earlier than planned, at 13:00 local time, to avoid a front near Chambéry. He refuelled the aircraft with 171 litres of aviation gasoline. At about 12:20, a staff member arrived at the airfield; it was raining. The pilot informed him he intended to depart towards Brünig and mentioned he would need to see how to get through near Geneva.
Later, the pilot spoke with a local flight instructor, who expressed surprise about flying in such weather. The pilot replied that above 7000 feet conditions were good and his main concern was getting through the "hole in Geneva" before it closed.
Passengers arrived at 12:50. The pilot said he would get further weather information from Meiringen once the airfield reopened after lunch.
From the airfield, the pilot observed that the Brünig pass appeared open despite clouds in the valley, with a broken layer on the Interlaken side and scattered clouds at various altitudes, estimating a 2000-foot cloud base at the pass.
Departure and Incident
After loading and engine start, the pilot called Alpnach control tower at about 13:10 on the common frequency. He repeated the call four times, apparently not hearing the replies; he believed the tower was still closed. During taxi, the pilot noticed the attitude indicator seemed to "hang" slightly but attributed it to low engine idle.
The aircraft departed runway 03 at 13:12. The pilot planned to fly downwind in the middle of the valley towards Brünig to avoid scattered clouds along the western side. During crosswind, he saw the cloud deck but the pass remained open. On downwind, he flew along the right slope, avoiding a cloud patch with a slight left turn, then turned right back towards Brünig. Another cloud forced him into a tight right turn; he maintained visual ground contact. He then entered a tight left turn to return to course but encountered a larger cloud. Due to the short distance, the aircraft entered the cloud. The pilot lost orientation and the aircraft collided with terrain in the Rütiwald area, about 3 km west of Kägiswil airfield.
Injuries and Damage
The pilot and two passengers sustained injuries: one passenger received fatal injuries, while the pilot and the other passenger received serious injuries. The aircraft was destroyed. Minor damage to forest occurred.