This means, they have exactly the amount of fuel they
need to get to their destination +45 minutes. Anything under that +45
minutes means an emergency. So that means these aircraft were getting
close to that emergency point. It's dangerous for the pilot, the
controller, and the passengers espicially.


One item that is missing is alternate fuel. Aircraft always take into
consideration fuel needed to get to an alternate airport in case of
warranting conditions. The 45-minutes reserve is contingency fuel to
account for unexpected holding, weather, and other delays at the
destination. It's not necessarily an emergency.


--
Mike