If their target were within fuel range, which India probably is, the attack would have taken place already.
If this is truly a planned event, it is more complicated than crashing an airplane into a building...unless that building is far far away and requires refueling and other preparations.
So who was on board?
Maybe nuclear scientists?
Government couriers carrying secret documents?
Engineers working on secret weapons?
If it is a highjacking, these are questions that need to be examined.
Or the crew went absolutely mad and there is no explanation...but that would have ended in a fireball long ago.