What caused the DC plane crash? Blackhawk helicopter may not have heard key transmission, NTSB says

WASHINGTON - A miscommunication and bad data may have contributed to last month’s deadly crash near Reagan National Airport.

The Blackhawk helicopter that crashed into the American Airlines flight preparing to land at Reagan National Airport on Jan. 29 may not have heard key instructions from the air traffic control tower as it approached the jetliner carrying 64 people on board, according to the National Transportation Safety Board. 

"The instruction was to pass behind the CRJ. That transmission was interrupted — it was stepped on. We do not have evidence on the cvr of the Blackhawk they may have not received the "pass the behind the,’" said NTSB Chair Jennifer Homendy.

The revelation came as the NTSB provided an update on the investigation into the crash Friday afternoon. Officials say they have now wrapped up the on-scene portion of their investigation.

NTSB also said approximately 20 seconds before the collision, the plane's collision avoidance system issued an alert but they have not yet confirmed if the system was recognizing the Blackhawk in that alert. 

READ MORE ON THR DC PLANE CRASH

The NTSB says they will continue their investigation and move the wreckage from DCA to a secure location.

Homendy also told reporters the Blackhawk’s actual altitude may have been different from what the helicopter’s flight instruments showed the crew.

"We’re confident with the radio altitude, radio altitude of the black hawk at the time of the collision that was 278 feet, but I want to caution, that does not mean that was what the black hawk crew was seeing," Homendy said. 

And as for the possibility that the black hawk pilots were looking at bad data, aviation expert Richard Levy said  that "what the pilots were seeing on their altimeters would’ve been accurate if, number one, the altimeter setting is set correctly, and number two, it has passed certification tests. Then it would be rare for it to be inaccurate."

 One other thing that came up during Friday’s press conference, the NTSB says they believe the helicopter crew was wearing night vision goggles. Levy said this would be a challenging environment for that and that the goggles can impact your peripheral vision.

Deadly DCA plane crash

The backstory:

Around 9 p.m. on Wednesday, Jan. 29, American Airlines Flight 5342 was inbound to Ronald Reagan National Airport at about 400 feet and a speed of about 140 mph when the plane rapidly lost altitude over the Potomac River, according to data from its radio transponder. 

A few minutes before landing, air traffic controllers asked the arriving commercial jet if it could land on the shorter Runway 33 at Reagan National, and the pilots said they were able. 

Controllers then cleared the plane to land on Runway 33. Flight-tracking sites showed the plane adjusting its approach to the new runway. 

Less than 30 seconds before the crash, an air traffic controller asked the Black Hawk if it had the arriving plane in sight. The controller made another radio call to the helicopter moments later: "PAT 25, pass behind the CRJ." Seconds after that, the two aircraft collided. 

The plane’s transponder stopped transmitting about 2,400 feet (732 meters) short of the runway, roughly over the middle of the river.