Investigators trying to determine what caused last week’s deadly midair collision between a US military Black Hawk helicopter and an American Airlines plane near Washington, DC, briefed lawmakers Thursday on what they’ve learned after combing through data from both aircraft and air traffic control.

The training of U.S. military helicopter pilots is getting heightened attention following the mid-air collision between an Army Black Hawk helicopter and a passenger jet.

A key safety system was turned off on the US Army helicopter that collided with an American Airlines regional jet last week near Washington’s Reagan Airport, killing 67. Senate Commerce Committee chair Ted Cruz told reporters the Black Hawk helicopter had turned off its automatic dependent surveillance-broadcast (ADS-B),

The pilots of the US Army helicopter that collided with an American Airlines Group Inc. regional jet near Washington last week were likely wearing night-vision goggles at the time of the accident. Preliminary information including the type of mission they were flying and crew communications indicates the pilots were using the device,