The goggles also limited the pilots' peripheral vision as they flew near Ronald Reagan Washington National Airport.

On the eve of the investigative hearings, Republican Sen. Ted Cruz introduced legislation called "The Rotor Act," which would require all aircraft, including military, to transmit ADSB location when flying -- a system that allows aircraft to transmit its location to other aircraft as well as to air traffic controllers.

The National Transportation Safety Board will question witnesses Thursday about air traffic control training, a key part of the investigation into January’s deadly midair collision at Ronald Reagan Washington National Airport.