Munich Air Disaster - Investigation

Investigation

Although the crash was originally blamed on pilot error, it was subsequently found to have been caused by the build-up of slush towards the end of the runway, causing deceleration of the aircraft and preventing safe flying speed from being attained. During the take off, the aircraft had attained a speed of 117 knots (217 km/h), but, on entering the slush, speed dropped to 105 knots (194 km/h), too slow for the plane to leave the ground, with not enough runway remaining to abort the take off. Aircraft with tail-wheel undercarriages had not been greatly affected by slush, due to the geometry of these undercarriages in relation to the aircraft's centre of gravity, but newer types, such as the Ambassador, with nose wheel landing-gear and the main wheels behind the centre of gravity, were found to be vulnerable. The accident resulted in the instigation of operating limits for the amount of slush build-up permitted on runways.

Despite this conclusion, the German airport authorities (who were legally responsible for the state of the airport's runways, but generally unaware of the danger of slush on runways for aircraft like the Ambassador) took legal action against Captain Thain, as the one pilot who had survived the crash. They claimed that he had taken off without deicing the wings and that responsibility for the accident was his alone, despite several witnesses stating that this was not so.

The basis of the German authorities' case relied on the icy condition of the wings hours after the crash and a photograph of the aircraft (published in several newspapers) taken shortly before take off, that appeared to show snow on the upper wing surfaces. When the original negative was examined, however, no snow or ice could be seen, the "snow" in the original having been due to the sun reflecting off the wings, which was clarified when examining the negative rather than the published pictures which had been produced from a copy negative. The witnesses were not called to the German inquiry and proceedings against Thain dragged on until 1968, when he was finally cleared of any responsibility for the crash. As the official cause, British authorities recorded a build-up of melting snow on the runway which prevented the Elizabethan from reaching the required take-off speed. Thain, having been dismissed by BEA shortly after the accident and never re-engaged, retired and returned to run his poultry farm in Berkshire. He died of a heart attack at the age of 54, in 1975.