Black Hawk battled faulty altitude data before Washington crash

Safety investigators probing January’s midair collision between an American Airlines Group Inc. regional jet and a US Army Black Hawk near Washington found a key instrument on the helicopter was displaying inaccurate altitude data that could have led the pilots to think they were flying lower than they actually were. 

The US National Transportation Safety Board on Wednesday kicked off a three-day hearing to pour over findings in its investigation into the crash that killed 67 people. 

“Investigators identified discrepancies related to the accident helicopter’s altitude,” said Chihoon Shin, an aerospace engineer at the NTSB. According to the agency, the Black Hawk’s so-called barometric altimeter, which determines altitude by measuring changes in air pressure, was showing the helicopter at 100 feet (30 meters) below the American Airlines jet at the time of the crash. 

It’s unclear, however, if the helicopter crew cross-checked that data against other devices like the radio altimeter, which determines altitude by measuring the time it takes for radio waves to travel to the ground and back to the aircraft.

The NTSB had previously said it was looking at whether the helicopter may have been getting faulty altitude readings, but this is the first time the agency confirmed findings on that front. 

The midair collision close to Ronald Reagan Washington National Airport, which was the worst US civil aviation disaster in decades, sparked renewed concerns about aviation safety and led to a crackdown on helicopter flights near the airport. It also helped galvanize support for major upgrades to the nation’s aging air traffic control system. 

The public sessions are digging into the equipment on the Black Hawk helicopter, the crowded airspace around Ronald Reagan Washington National Airport and air traffic control training and procedures at the hub. 

There are often multiple factors that lead to a tragedy like January’s midair collision.