Voice recordings from the Black Hawk helicopter involved in the crash with a commuter plan in Washington, DC, on January 29 have been released by the NTSB in a briefing for reporters Friday.

The NTSB is turning the focus of its investigation into the Jan. 29 collision on what the Black Hawk pilots could see and hear.

The National Transportation Safety Board says altimeter in the Black Hawk helicopter may have malfunctioned before the DCA mid-air collision with an American Airlines jet. All 67 people aboard died.

WASHINGTON (AP) — The crew of the helicopter that collided midair with an American Airlines jet near Washington D.C.’s Ronald Reagan National Airport might not have heard instructions from the air traffic controller to pass behind the plane, investigators said Friday.

The National Transportation Safety Board is also studying whether the pilots of the Black Hawk in last month’s collision were seeing accurate data about the helicopter’s altitude.

The National Transportation Safety Board said the helicopter’s cockpit voice recorder didn’t capture key directions from air-traffic control and is investigating whether the crew might have seen a different altitude on the flight instruments.