The Pan International crash was caused by fuel in the water tank. I believe that several (5 I think) containers were used to to to fill the water tank, 2 of which contained fuel that had been drained from another aircraft, but not marked as such. The fuel would have floated on the top of the water so that initially, during take off, all would be normal as the water was taken from the bottom of the tank, until the level got down to the fuel when there was a sudden over-temp of both engines. The water flow rate was higher than the fuel flow so the effect would be catastrophic on the hot end.
IIRC the luck and bad luck was the Autobahn they landed on had a bridge that they went under. It had no centre pillar so when a wing hit on one side the aircraft slewed sideways and broke apart. Had there been a centre pillar then both wings would have hit and the fuselage may have carried on in a straight line and remained intact.