The "NZZ am Sonntag" today printed an article with the headlines "Die JU-52 flog an ihrer Leistungsgrenze" which translates as "the JU was flying at its limits", a statement I made longtime ago in this forum and was bashed for it by people who thought to know better. The author of the article, aviation journalist Mr. Sepp Moser suggested that a vapour lock might have caused a coughing of one of the engines which made the pilots turn away rather abruptly to avoid rising terrain. Considering the fact that the aircraft was parked in Locarno under a blazing sun until 16:00 and that the Junkers has no gravity fuel feed, its a possible scenario, even more so because booster pumps should not be used at altitude because they make the engines run too fat.