National Transportation Safety Board Chairwoman Jennifer Homendy told reporters that the recording from the Black Hawk helicopter cockpit suggested an incomplete radio transmission may have left the crew without understanding how it should shift position just before the Jan. 29 crash, in which all 67 aboard the two aircraft were killed,

The NTSB gave an update on its investigation into the Potomac River crash between an American Airlines jet and an Army helicopter in January.

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.