Report on aviation accident at Trondheim Airport, Værnes on 13 June 1976 with Piper Super Cub PA-18-150, LN-NPM
Aviation report 1979/06
On 13. June 1976 LN-NPM was to tow two gliders from Værnes to Notodden. The departure was normal and the two gliders found their predetermined positions behind the tow plane. When the aircraft had achieved about 40–50 m height, the tow plane suddenly turned to the left. It then straightened, made a few undulating movements, and suddenly dived towards the ground. The sailplane in front released from the tow plane automatically during the turn. The rear sailplane released when the tow plane started to dive. The pilot of the tow plane died instantly when the plane impacted the ground.
The tow from Værnes to Notodden had been postponed due to technical issues with LN-NPM. It had been necessary to change two of the engine cylinders and fix an issue with the ignition. The investigation has, however, not found signs of technical failure of the engine before the crash.
The turn to the left at a low height was not planned, and the accident investigation board views this as a contributing factor to the accident. The accident investigation board has not found a clear answer as to why this turn was performed. Several hypotheses have been investigated, and the board highlights that the tow plane turned towards one of the best areas for an emergency landing outside the airport. This can indicate a non-critical problem, but the investigation has not found anything concrete. The accident investigation board also holds the opinion that the late release of the rearmost glider might have contributed to the tow plane diving.
Published 21.05.1979
Facts
| Location | Trondheim Airport Værnes, Norway |
| Occurrence date | 13.06.1976 |
| ICAO Location indicator | ENVA |
| Aircraft | Piper Cub-series |
| Registration | LN-NPM |
| Meteorological conditions | VMC |
| County | Nord-Trøndelag |
| Type of occurrence | Accident |
| Category of operation | Light, aeroplane (< 5 700kg) |
| Aircraft category | Landplane, Single-engine |
| FIR/AOR | ENBD (Bodø ATCC) |