(AP) — Federal accident investigators are urging the adoption of new air traffic control procedures for handling aborted landings after five near collisions involving airliners.

The National Transportation Safety Board said in a letter Monday to the Federal Aviation Administration that current procedures should be modified so that in cases where two planes are departing at once, controllers shouldn’t also clear a plane to land at a time it would create the potential for a collision if the flight crew of the landing plane decides to abort the landing and go around for another attempt.

NTSB said there were four such near collisions last year: two in Las Vegas, and one each in New York and Charlotte, N.C. There was also a similar near collision in Las Vegas in 2006.