Malaysia Airlines Flight MH17 was guided off its most recently used course as its pilots hoped to avoid thunderstorms brewing in the south of Ukraine, it has been claimed.
When it was shot down, the doomed jet was many kilometres north of the flightpaths from Amsterdam to Kuala Lumpur it had used on previous days.
Nico Voorbach, a pilot who flew the same journey earlier this northern summer for KLM, and who is president of the European Cockpit Association, said poor weather may have been the reason why flight MH17 found itself in the sights of a surface-to-air missile launcher.
Voorbach said: "I heard that they were diverting from some showers. I think there were thunderclouds.
You would ask air traffic control to divert left or right, and they would give you the permission."
It also emerged yesterday that flight MH17 had initially filed a flight plan requesting to fly at 35,000ft (10,668m) above Ukrainian territory. On entering Ukrainian airspace, however, the plane's pilots were instructed to fly at 33,000ft by the local air traffic control because of other traffic.
Malaysia's transport minister, Datuk Seri Liow Tiong Lai, told a press conference MH17's flight path was considered a safe route. "MH17 flew at an altitude that was set and deemed safe by local air traffic control, and it never strayed into restricted airspace. The flight and its operators followed the rules. But on the ground, the rules of war were broken."
In response to claims that weather led to flight MH17 changing its flight plan, Malaysia Airlines director of operations Izham Ismail said they had no reports from the pilot to suggest that was the case.
The UK Civil Aviation Authority recently urged UK-based airlines not to fly over a wide area near the Crimea, Black Sea and Sea of Azov, and several airlines have followed that advice. Others, however, had been continuing to use the route, one of the "aerial motorways" between northern Europe and south Asia.
Malaysia was one of more than a dozen airlines which flew the route on Thursday. MH17 was only a few kilometres from an Air India Boeing 787 and a Singapore Airlines 777 when it was shot down.