The first of the National Transportation Safety Board’s three days of investigative hearings is underway to help determine what caused the deadly midair collision on January 29 between an Army helicopter on a training mission and American Airlines flight 5342 landing at Ronald Reagan Washington National Airport.

Investigators have found that a helicopter involved in a deadly crash with a passenger plane over Washington was flying above its height limit

The head of the National Transportation Safety Board sharply criticized U.S. officials for failing to act before the January 29 collision of a U.S. Army helicopter with an American Airlines regional jet in Washington that killed 67 people.