A preliminary analysis of the flight data and voice recorder on board a Black Hawk helicopter leading up to the collision with a commercial flight over Washington, DC, on January 29, indicated the helicopter’s altimeter may have been inaccurate and the pilots may not have heard some calls from the Reagan National Airport control tower,

Analysis of black box shows ‘conflicting information’ and suggests cockpit may not have seen accurate altitude information

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.