Investigators so far have highlighted several factors that may have contributed to the collision, which left 67 people dead.

Friday was the final day of the National Transportation Safety Board's (NTSB) three-day hearing on the deadly plane crash at Reagan Airport that took the lives of 67 people in January.

The hearing, the second of three days, focused on the training guidance of the parties involved in the Jan. 29 incident that resulted in the deaths of 67 people. NTSB started the daylong hearing examining the responsibilities and readiness of DCA's air traffic controllers.