Military helicopter traffic over Washington was a longtime worry among aviators operating around the airport where an Army helicopter and commercial airliner collided this year, killing 67 people, federal investigators heard during testimony on Thursday.

The Army helicopter that collided with a plane over D.C. in January had incorrect altitude readings, contributing to the aircraft getting too close.

Tuesday is day two of a three-day hearing on the deadly plane crash at Reagan Airport that took the lives of 67 people in January.