His plane is described as a single engine 1968 Piper Cherokee with a tail number of N4151R, and as being white with red and blue wings. Martin was last believed to be in Tonopah near Round Mountain.

A crumple of silver and red. "That's the plane," says our guide, Dominik Nellen, pointing. Below us on the Aletsch glacier is the wreck of a Piper Cherokee aircraft lost in 1968. Hidden for more ...