Airline pilots have warned of the potential dangers that helicopters posed in the Washington area before the fatal crash at Reagan National Airport on Wednesday night. A database of aviation safety issues maintained by NASA details two startling incidents in recent years that involved passenger jets nearly colliding with helicopters near the airport.

Bill Pearce, a commercial pilot from Maryland who has worked for several major airlines, says flying in and out of Ronald Reagan National Airport near Washington, D.C. is tough for pilots and air traffic control.