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

A key safety system was turned off in a US army helicopter when it crashed into an American Airlines flight last week, killing 67 people.