Investigators are seeking clues into this week's deadly midair collision, the deadliest aviation disaster in the U.S. almost a quarter century.

The airspace around Washington, D.

Delta Air Lines says the pilot accused of threatening to shoot the plane’s captain during a flight no longer works for the airline.

Aviation experts say the incident in which an off-duty pilot tried to disable a jetliner in midflight renews questions about the threat posed by insiders — airline workers who have special access to places where passengers can't go.