It doesn’t work that way. Delta operations started the ball rolling, mostly likely in close coordinated with the FAA (every airline has risk assessment teams that work closely with their local FAA office). UAL’’s afternoon flight was next, after the FAA issued their NOTAM. US Airways cancelled only tonight’s flight after the FAA issued their NOTAM. US Airways is going day to day.
Quoting from an article ...
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On Tuesday, four major U.S. airline carriers announced their decision to cancel flights heading to Israel indefinitely, one specifically citing the danger of Gaza rocket attacks near Israel’s Ben Gurion airport.
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Israel Transportation Minister: Cancellation of Flights to Israel Gives a ‘Prize to Terror’
http://www.freerepublic.com/focus/news/3183687/posts?page=35