The National Transportation Safety Board has finished on-scene investigation of January's fatal crash between a regional jet and an Army Black Hawk helicopter near Reagan National Airport. On Friday, agency officials shared more details about the events leading up to the crash.
The crew aboard the helicopter were wearing night vision goggles for a qualification flight.
The tower had communicated to the helicopter that the CRJ700 it would later collide with was circling. Evidence from the cockpit voice recorder aboard the Black Hawk suggests this information may not have been fully communicated to the Black Hawk crew. The NTSB is investigating that discrepancy.
The tower then directed the Black Hawk to "pass behind the CRJ." Data reviewed by the NTSB suggests the Black Hawk crew may not have received a portion of the message telling them to "pass behind the" other aircraft.
NTSB chair Jennifer Homendy cautioned that the radio altitudes captured by flight recorders and the altitudes the flight crews saw from their main instruments may have conflicted.
"We are seeing conflicting information in the data, which is why we aren't releasing altitude for the Black Hawk's entire route," Homendy said Friday.
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NTSB officials also said they have identified "bad data" in the altitude measurements captured by the Black Hawk's flight recorder. The agency will have to work with Sikorsky, the helicopter manufacturer, and review the physical debris from the wreck to reconstruct the exact behavior and any malfunctions that may have occurred in the altitude instruments.
As part of its investigation, NTSB will conduct a visibility study, in which it measures the cockpits of both aircraft and accounts for the variables introduced by night vision goggles, to determine exactly what the pilots of both aircraft could see during the incident.
The agency has not yet issued a final report about the crash. Homendy reiterated to reporters on Friday that it will take time to completely investigate all of the data and variables involved in the incident.
