CHICAGO (AP) — New air traffic control procedures have been put in place at Chicago’s O’Hare International Airport to try to eliminate the risk of midair collisions over a pair of runways, after two near misses last year raised serious concerns, federal officials said Wednesday.

The planes involved in the incidents, which occurred three months apart in 2011, came within a few hundred feet of each other, according to a preliminary report released this week by the National Transportation Safety Board. No one was hurt, but the crew of one of the planes had to delay their takeoff and stay low to avoid a collision even though they were rapidly approaching the end of the runway.