Accident to the Van's RV7 registered D-EIOI on 29/08/2018 at Bourg-Saint-Maurice

Investigation progression Closed
Progress: 100%

The pilot took off for a VFR flight from Fribourg-en-Brisgau aerodrome (Germany). The pilot initially headed towards the Feldberg where he had arranged to meet, in flight, a friend piloting a Van’s Aircraft RV7A registered D-EKPM. The plan was to fly to Cuers-Pierrefeu aerodrome (in the Var), on a transborder flight plan. From 18:12, the D-EIOI pilot had difficulties with maintaining visual contact with D-EKPM due to the meteorological conditions encountered. At 18:29, he lost sight of D-EKPM and disconnected the autopilot before tracking south and starting to climb. At 18:33, the EFIS data indicates the first icing phenomenon affecting the carburettor characterized by a decrease in the manifold pressure of the engine. From 18:39, the D-EIOI pilot continued climbing and started manoeuvring above 10,000 ft. A minute later, the EFIS data again shows an icing phenomenon affecting the carburettor managed by the pilot. At 18:49, he flew 360° to continue climbing and manoeuvred above 12,500 ft. At 18:56, the D-EIOI pilot said that he was “in clouds” and then “out of clouds” and that he was heading towards Megève altiport. Five minutes later, the aeroplane was abeam Mont Blanc at an altitude of 14,435 ft. At around 19:05, the manifold pressure of the engine decreased a third time again because of an icing phenomenon affecting the carburettor. The pilot lost control of the aeroplane which descended 4,600 ft in 35 s. During this phase, the aeroplane was probably on its back with a nose-down attitude which reached 80 degrees. The path then stabilized and the aeroplane was momentarily flat with full power just before colliding with the terrain.

The following factors may have contributed to the accident: an inadequate analysis when preparing the flight, of available weather forecasts consistent with those observed and estimated during the accident flight and of the possible diversions according to the meteorological conditions encountered in flight, and continuing the flight by tracking towards the highest massifs of the Alps in adverse/incompatible weather conditions for a flight under VFR.