A Swiss Air Force helicopter, that claimed the lives of two pilots when it crashed on Wednesday, was brought down by a collision with a power line, Swiss public television SRF reports.
Military investigators have identified the cause of the crash, that happened near to the Gotthard Pass in central Switzerland, but still do not know if the collision was caused by pilot error or other factors.
The military authorities had earlier played down the chances of mechanical error while investigators said there appeared to be nothing wrong with the overall management of the exercise.
The power cable was classified as an obstacle, not a flight risk, as it did not rise more than 25 metres above the ground, reported the Schweiz Aktuell programme.
The Super Puma helicopter was taking off after unloading personnel from a Organization for Security and Co-operation in Europe (OSCE) mission that was inspecting Swiss army installations. The pilot and co-pilot were killed and a flight assistant badly injured.
The accident followed the fatal crash of an F/A-18 military jet in central Switzerland in August that claimed the life of its pilot.
Military exercises and an annual public live firing display at Axalp, canton Bern, due to be staged between October 11-13, have been cancelled as a mark of respect to the four victims of the crashes.
swissinfo.ch with agencies