My information is different (e.g. Greenwalds account: Without enough fuel to fly an alternative route, the Bolivian pilot was forced to make a U-turn and land in Vienna.)
If the pilot had enough fuel to reach his original proposed refuelling stop in the Canary Islands, he had enough fuel to get back to Russia
(The cockpit audio suggests the pilot actually was worried about the amount of fuel he had left as he reported an issue with his fuel gauge, but "Morales forced to land by minor technical issue" isn't quite as compelling a story...)
(The cockpit audio suggests the pilot actually was worried about the amount of fuel he had left as he reported an issue with his fuel gauge, but "Morales forced to land by minor technical issue" isn't quite as compelling a story...)