The crew of the Army helicopter that collided with an American Airlines plane in DC may have had inaccurate altitude readings before the crash, investigators said. They also may not have heard key instructions to move behind the plane. The National Transportation Safety Board revealed that an incomplete radio transmission left them unaware of how to shift position before the January 29 crash, which killed all 67 people aboard both aircraft. ‘That transmission was interrupted — it was stepped on,’ the spokesperson said, leaving them unable to hear the words ‘pass behind’ because the helicopter's microphone key was pressed at the same moment. Read the full story at DailyMail.com. #news #dc #planecrash #blackhawk #dcplanecrash #airtraffic