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.

The National Transportation Safety Board wrapped up a three-day investigative hearing into the mid-air collision between a helicopter and passenger jet in Washington that killed 67. New information confirms the crew of the Army helicopter faced several problems,

A three-day National Transportation Safety Board hearing on the deadliest U.S. aviation accident in decades dug into problems with altimeters, chopper routes and the busy Washington, D.C., airspace.