Introduction
On 5 July 1963, a Jodel D-ll aircraft, registered HB-SOL, was destroyed in an accident near Giswil, Canton Obwalden, Switzerland. Both occupants, the pilot and a passenger, sustained fatal injuries. The aircraft was operated by the Motorfluggruppe der Sektion Biel des Ae.C.S. and was on a private flight from Ascona to Biel.
Flight and Accident
The pilot and passenger had flown from Biel to Ascona on 3 July 1963 and spent two days in Ticino. On the morning of 5 July, rain in the Locarno area prompted the pilot to delay the return flight until the afternoon upon advice. At 1516 MEZ, after refueling and two local flights, the pilot departed Ascona for Biel. He had briefly discussed weather conditions with an aircraft mechanic, indicating he would return if conditions were unfavorable.
The aircraft traversed the Alps and at 1609 emerged from clouds at about 1600 m AMSL in the Giswil area. During the ensuing pull-up maneuver, the aircraft broke up in flight. The wreckage fell near Grossteil, coordinates 655.500/187.700, elevation 500 m AMSL, within the municipality of Giswil.
Aircraft and Crew
The aircraft was a Jodel D-ll, a two-seat low-wing wooden monoplane with a Continental C-90-12-F engine. It was not equipped or certified for instrument flight. The pilot held a private pilot license issued 30 June 1960, valid until 28 July 1963, and had logged approximately 170 flight hours, with 65 hours on type. He had completed 15 Alpine crossings. The passenger had no flight experience.
Weather
The general weather situation featured a flat pressure distribution over central Europe. The Alpine region was mostly cloudy with scattered thunderstorms. The actual en-route weather from Ascona to Giswil included increasing cloud cover; near Giswil at the accident time, the sky was 7-8/8 cloudy, with mountain peaks in clouds and some fog banks on slopes. The cloud base was around 1600 m AMSL with tops at 2500 m AMSL, and an upper layer from 2800 m AMSL to 4000-4500 m AMSL. Turbulence was not significant below 3000 m AMSL, and light icing existed above 3000 m AMSL.
Investigation
The official investigation, conducted by the Eidgenössische Flugunfall-Untersuchungskommission, found no pre-existing technical defects on the aircraft. The pilot had not received instrument flight training, and the aircraft was not approved for instrument flight. The investigation noted that the pilot had a previous incident in September 1962 involving inadvertent entry into clouds. No health issues at the time of the accident were identified. The report did not state a probable cause for the in-flight breakup.