Just before DC crash Army helicopter may not have heard order to go behind jet: NTSB

WASHINGTON -- The crew of the Army helicopter that collided in midair with an American Airlines jet near Washington, D.C.'s Ronald Reagan National Airport may have had inaccurate altitude readings in the moments before the crash, and also may not have heard instructions from air traffic control to move behind the plane, investigators said Friday.

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,

"That transmission was interrupted -- it was stepped on," she said, leaving them unable to hear the words "pass behind the" because the helicopter's microphone key was pressed at the same moment.

Homendy said the helicopter was on a "check" flight that night where the pilot was undergoing an annual test and a test on using night vision goggles. Investigators believe the crew was wearing night vision goggles throughout the flight.

It will take more than a year to get the final NTSB report on the collision, and Homendy warned reporters that many issues were still being probed.

SEE ALSO: All major pieces of the plane and helicopter from deadly DC midair collision recovered, NTSB says

"We're only a couple weeks out," from the crash, she said. "We have a lot of work to do."

The collision was the deadliest plane crash in the U.S. since 2001, when a jet slammed into a New York City neighborhood just after takeoff, killing all 260 people on board and five more on the ground.

The collision likely occurred at an altitude of about 325 feet, investigators have said, which would put the Black Hawk above its 200-foot limit for that location.

Cockpit conversations a few minutes before the crash indicated conflicting altitude data, Homendy said, with the helicopter's pilot calling out that they were then at 300 feet, but the instructor pilot saying it was 400 feet, Homendy said.

"At this time we don't know why there was a discrepancy between the two," she said.

Almost immediately after the crash, President Donald Trump publicly faulted the helicopter for flying too high. He also blamed federal diversity and inclusion efforts, particularly regarding air traffic controllers. When pressed by reporters, the president could not back up those claims. A few days later, Trump placed the blame on what he called an "obsolete" air traffic control system.

Sullivan reported from Minneapolis.