The investigation into the deadly midair collision between an American Airlines jet and a Black Hawk helicopter is revealing a critical safety system on the helicopter was turned off at the time of the crash.

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.

A 3-D model created by The Times visualizes the helicopter pilots’ field of view minutes before a fatal crash with a jet in Washington.

The incident comes a week after an American Eagle regional jet collided with an Army Black Hawk helicopter over the Potomac River near Washington D.C. The reasons as to why the plane was interrupted in its journeys over the past month is unknown

The Army pilots were juggling dark skies, low altitude, a busy airspace and a cockpit without certain traffic detectors before the helicopter’s midair crash with a regional passenger jet.

The U.S. Army helicopter that collided with an passenger jet near Washington, D.C., had an advanced surveillance system turned off.

A key safety system was turned off on a U.S. Army helicopter that collided with an American Airlines regional jet last week near Washington 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 Army Black Hawk helicopter involved in the fatal midair collision in Washington, D.C., had a tracking system turned off, Sen. Ted Cruz said.