The deadly mid-air collision at Reagan Airport in January was years in the making, the operations manager of the DCA air traffic control tower on the night of the accident told the National Transportation Safety Board on Friday.

The National Transportation Safety Board questioned witnesses Friday on collision avoidance technology and organizational systems to manage risk. It is the third and final day of investigative hearings probing January’s midair collision between a US Army Black Hawk helicopter and an American Airlines regional jet,

March 13: Sen. Moran and Sen. Ted Cruz (R-Texas) press the Army to answer questions regarding the Army’s role in the midair collision on January 29th. March 27: The Senate Commerce Subcommittee on Aviation holds a hearing on the January 29 midair collision.