Probing the 29 January mid-air collision of an American Airlines CRJ700 and a U.S. Army UH-60 Black Hawk helicopter over the Potomac River, US National Transportation Safety Board (NTSB) investigators have identified from preliminary data an altitude discrepancy between their initial read of the regional jet’s flight data recorder (FDR) and what controllers would have seen on their screens in the Reagan National Airport (DCA) control tower cab.
All 67 people on board the two aircraft — 64 on American Flight 5342 from Wichita, Kansas, as flown by its subsidiary PSA Airlines; and three servicepeople aboard the helicopter, which was on a training flight — perished in the collision.
“Our team has had some internal debate on releasing one part of this. And whenever I explain it, I hope you’ll understand why,” NTSB member J. Todd Inman warned during a Saturday, 1 February media briefing following the earlier recovery of the CRJ700’s cockpit voice recorder (CVR) and FDR by an FBI dive team, and the extraction of the combination CVR and FDR from the helicopter.
“When we received the recorders from the CRJ, we were able to define an altitude of where it was very close to the time of impact,” he said. “That is a data point we feel very comfortable with. We also have an initial set of information in regard to what was being seen on the cab in the control tower. We have not finalized that and need to get more granularity to it. And we currently don’t have the readout from the Black Hawk. I put all that into context for you in that whenever I give you some altitude information, one part of three pieces we have defined. Another part we feel fairly confident but need to get more information, and a third we don’t even have.”
With that strong preface, Inman revealed: “Currently the CRJ, based upon the data recorder at the time of impact, was at 325ft, plus or minus 25ft.” This, he said, is “a corrected altitude; it is based on the ADS-B data and the flight data recorder.” Meanwhile, NTSB’s “preliminary review of what the tower cab was showing on the data screen that would have been in front of the controllers was 200ft near the time of the accident.”
“Again, this data is preliminary,” he stressed, with additional data sources being analyzed that will confirm precisely what altitude would have been on the screen at the time. “And I would also caution you, there’s typically in the cab on that screen, it may be a four to five second refresh rate, but obviously this is something that we’re going to be looking at very closely.”
Pressed multiple times by journalists to clarify if there was a 100ft discrepancy between what the air traffic controller was seeing on the screen in front of them and the altitude of the CRJ, Inman reiterated:
I’m saying the initial data we have on the control tower cab says 200ft would have been visualized. This is a fairly good initial read. It needs to be finalized. And again, the CRJ was operating at 325ft plus or minus 25.
Inman said the NTSB cannot yet give any information on the altitude of the helicopter (Priority Air Transport 25 or PAT25). But he called the helicopter recorders “the third prong” of information that needs to be confirmed to understand the conflicting altitude information being seen in preliminary data. Whenever those data points are finalized, NTSB will feel “very comfortable” in saying exactly what altitude this collision occurred at.
Various media reports suggest that the PAT25 may have flown above its max limits. But Inman told journalists he hadn’t heard that and doesn’t try to look at the media. Board investigator Brice Banning provided context, saying: “The PAT25 was within the lateral boundaries of a helicopter route. The ceiling of that route was 200ft. As member Inman said, we have not got the data out of the FDR for the Black Hawk at this time, but that’s what we know.”
As to whether the CRJ was trying to pull up before the collision, Inman said: “I can tell you at a one point very close to the impact, there was a slight change in pitch, an increase in pitch. That is something that we will get you more detail on, but it was an indication of an increase in pitch.”
Currently being analyzed by a working group comprising NTSB, FAA and PSA Airlines, the FDR contains about 400 parameters. Meanwhile, a CVR group consisting of representatives from NTSB, PSA, ALPA and the FAA is transcribing the entirety of the CVR recording verbatim. Investigators observed a water intrusion in the CVRs of both the CRJ and the helicopter but stressed that this is not uncommon and that they feel confident they’ll have the data.
The CRJ pilots were communicating via VHF whilst the military pilots were on UHF, also a common occurrence. There were five controllers in the air traffic control tower cab at DCA at the time of the accident. The NTSB did not hold a press briefing on 2 February.
Featured image credited to NTSB
