When I was deeply involved in RAF flying training I was briefed by the Scientific Staff that detailed analysis of RAF selection tests showed that the only factors in selection that gave a better than random prediction of success were youth and previous flying experience.
But the RAF training system is (was) not the same as the civilian system so this is not directly transferable. For example, we expected to have to train out poor leadership, poor co-operation and overconfidence as well as teaching flying skills
Dick