Andreas Lubitz locked pilot out of cockpit and 'deliberately ' crashed A320 . Flew the plane into French Alps at 400mph and killed 150 people on board . FlyBe , Virgin Atlantic and Norwegian introducing rule to avoid disaster . Jet2 , Monarch , EasyJet and RyanAir say the procedure is already in place . Industry insider said practice could become 'mandatory ' across all airlines .
Andreas Lubitz locked pilot out of cockpit and 'deliberately ' crashed A320 . Flew the plane into French Alps at 400mph and killed 150 people on board . EasyJet , Virgin Atlantic and Norwegian introducing rule to avoid disaster . Jet2 , Monarch , FlyBe and RyanAir say the procedure is already in place . Industry insider said practice could become 'mandatory ' across all airlines .