NTSB livestream - briefing 5 for Potomac crash

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Techhead7890@reddit (OP)

For context, this is the pdf briefing notes on the NTSB website.

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NeverNo@reddit

It says the CRJ started pitching and to the left one second before the collision - would this suggest they saw the Black Hawk and tried to avoid?

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FloridaWings@reddit

Why would they ever design a procedure that left that little margin for error? 100FT seriously??

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biggsteve81@reddit

Because there was supposed to be horizontal visual separation. Which obviously doesn't work if you are looking at the wrong aircraft.

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This is always going to be a risk of visual separation. As someone who doesn't want the government to control GA flying too strictly, I don't think we should get rid of vis sep altogether. But there do need to be limits, particularly this close to an active runway with commercial traffic.

At the very least, I would have liked it if the helicopter pilots were required to read back the runway number for the traffic they're looking for. At the very least. Could have made all the difference here.

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curiosity-12@reddit

Do you think the rules should be any different for congested / restricted areas at night? Or that NVG usage should be limited in those areas? Not trying to be provocative, legitimately interested in your opinion because you know more than I do!!

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GaiusFrakknBaltar@reddit

For flying at night in busy airspace, yeah they probably shouldn't do vis sep unless it's a lower class airport with less traffic. For DCA and airports like it, I think this would be a good call though.

As far as NVG, I don't know enough about their operations to say. It sounds like they were using NVGs for safety reasons, especially flying at low altitudes. So that would have to be balanced with the fact it's going to make identifying conflicting traffic more difficult. How to find that balance? Idk, I just don't know enough.

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rocourteau@reddit

Were they not using NVG for training purposes? The main issue with them is the elimination of peripheral vision, requiring much more attention to perform scans for traffic.

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GaiusFrakknBaltar@reddit

I watched an NTSB conference that led me to that conclusion, but you're probably right, I just inferred that. Can't remember exactly what was said anymore.

My question is why do they need NVG's? Not trying to be contrarian, just curious. My assumption was so they can avoid radio towers and cranes, but perhaps there's some military reason for it.

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rocourteau@reddit

In mil ops, NVGs are used to fly low-altitude missions over unfriendly territory and for search-and-rescue missions. Since their use requires specific procedures, training with them is essential.

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Temporary-Fix9578@reddit

Because that entire airspace is held together with bubblegum and prayers

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Glum-Topic-669@reddit

Very interesting regarding the discrepancy of the altitude readings. So it's possible then 1 of the altimeters were either set to the wrong pressure correction setting or perhaps had a static port blockage and its pressure reading efffected, and which why NTSB referring to this as "bad data"? And am I correct that the ATC receives altitude readings from the primary altimeter? From my research, an error reading of the conflicting amount seems possible on an altimeter setting of '1000 feet per inHg' for the weather conditions/pressure that were apparent at the time of the incident.

Such a shame about the radio transmissions not being so smooth.

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Mightyduk69@reddit

ATC would get readings from all the data available, I think it shows the best available on the screen. That they had ADS-B not broadcasting meant the ATC wasn't getting the best. That said, the separation error was a huge factor that we shouldn't lose sight of over a 50-100' vertical error. They should have been hundreds of feet away.

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Techhead7890@reddit (OP)

Just want to add an addendum (can't edit this type of OP I guess) that this is the fourth briefing. It was a typo.

For context, I copied the stream title which originally said briefing 5, and just assumed there was an offline briefing at some point since the third one a week back. They have since corrected it on YouTube to say four; but this type of fix is unfortunately not possible on reddit.

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HonoraryCanadian@reddit

Haven't listened yet, but maybe someone who has can answer a couple questions:

Were Tower's instructions to the helicopter heard on the CRJ CVR? If so, did the CRJ pilots ever discuss that they were the ones being pointed out to traffic?

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801mountaindog@reddit

No one talks about their airplane being pointed out to others the vast majority of the time.

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graphical_molerat@reddit

They were on a different frequency, and unaware of ATC talking to the helicopter.

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HonoraryCanadian@reddit

The synopsis listed above says the tower transmission to the helicopter two minutes prior to impact was heard on the CVR of the CRJ. So tower appears to have transmitted on both frequencies, even as the aircraft were each only listening and transmitting on one.

But more to the point, the CRJ had the opportunity to realize they were the traffic pointed out to the helicopter, but did they?

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clocks212@reddit

If the CRJ was in a 10 degree left turn and was hit by the Blackhawk in the left side they probably never saw it (at least not at any point during their turn).

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AbsurdKangaroo@reddit

If you look at the report today it confirms that they had control inputs full elevator up which is an extremely aggressive input. It also confirmed they had rolled out onto final so werent turning anymore. That sounds to me like the CRJ crew did see the helo at the last moment which feels almost more tragic.

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railker@reddit

I'm also imagining the TRAFFIC, TRAFFIC callout from TCAS was the helicopter -- the only other close traffic was the American flight taking off from runway 1, but they were faster and over a mile and a half away, I'm not sure TCAS would've predicted that as a conflict. Would protocol for such a callout have been for the FO to look for the traffic on such a short final on a circling visual approach to a runway?

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TH3J4CK4L@reddit

If I was to do wild and irresponsible speculation, I would say: the protocol for a TA on short final for DCA RWY 33 is to ignore it... (Since it occurs so frequently due to helo traffic.)

One might say that's an unsafe procedure, others might say that it's been safely done multiple times a day for decades (conceivably a hundred thousand times, and this is the first ever crash between a US military helo and a civilian aircraft).

As always, we'll have to wait for the final report.

(Also, the CRJ might have been in a left bank at the time, so the help might not have been visible even if they were looking.)

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m149@reddit

The CRJ was initiating a climb at the time of impact....too late unfortunately. They saw the heli.

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TH3J4CK4L@reddit

The commenter asked about the time of the TCAS TA, not the time of impact.

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railker@reddit

They may have been on different frequencies, but the NTSB notes the transmissions ATC made to the helicopter were heard on the CRJ's CVR. I believe the Blackhawk's responses were what weren't audible to the crew of the CRJ, as ATC has the ability to transmit on multiple frequencies at once to ensure all traffic can hear their instructions without having to switch frequencies around.

The Airport Diagram for KDCA lists 119.1, 257.6 and 134.35 as Tower frequencies (the latter for helicopters.

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Mission_Nin@reddit

stepped on by a 0.8 second mic key from the Black Hawk.

Does this suggest that they "jumped the gun" on their response? Too dismissive of ATC? Not really listening?
As before it seems like they either don't see the CRJ or misjudge the distance

Also the Black Hawk crew may not have been aware that the CRJ was switching runways. - is this correct or do they just miss the word "circling" but still hear "runway 33"?

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Mission_Nin@reddit

"stepped on by a 0.8 second mic key from the Black Hawk."
Sorry, what does that mean? Were they responding too quickly?

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RedSquirrel17@reddit

Just watching now, important points:

The Black Hawk crew was "likely" wearing NVGs during the flight. If they had been planning to not wear them, they would have been required to hold a pre-flight discussion about operating the flight unaided. There is no evidence of such a discussion.
The instructor pilot was the Pilot Monitoring (PM) and was monitoring the radio.
When the Black Hawk as about 1.1 nautical miles west of the Key Bridge, the Pilot Flying (PF) indicated they were at 300ft, while the PM indicated they were at 400ft. Neither pilot commented on the altitude discrepancy. The cause of this discrepancy has yet to be determined.
As the Black Hawk approached the Key Bridge, the PM indicated that they were at 300ft, descending to 200ft.
As the Black Hawk overflew the Memorial Bridge, the PM told the PF that they were at 300ft and needed to descend. The PF said they would descend to 200ft.
The final transmission from the Tower to the Black Hawk ("Pass behind the CRJ") was not fully audible to the crew as the transmission was stepped on. The Black Hawk keyed the mic.
The CRJ's last attitude was recorded as 9 degrees up and 11 degrees roll to the left.
The Black Hawk's final radio altitude before the collision has been determined to be 278ft above the terrain. This has been fully validated, so there is a high degree of confidence that this is good data.
It has not yet been determined what the pilots saw on their barometric altimeters, as this is not recorded on the FDR. Further investigation is necessary to determine this.
The two aircraft were operating on two different VHF frequencies. Neither aircraft was operating on UHF.

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McCheesing@reddit

Amazing write up. Thank you for this!

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rhineauto@reddit

Something else that I thought was interesting

At 8:47.44 the crew said they had the traffic in sight and requested visual separation, which was approved. The PM then told the PF they believed ATC wanted the helicopter to move left, towards the east bank of the river.

If you look at the ADSB data, right around this time the helicopter started turning right.

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TH3J4CK4L@reddit

You may want to edit your comment to clarify that we do NOT have ADSB data for the Blackhawk.

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railker@reddit

An important part of looking at that track, I believe, is that there is no ADS-B data from the helicopter. Its position as shown on ADSBExchange or other sites is sourced from MLAT. As described on ADSBExchange's FAQ page:

MLAT is derived from multiple receivers receiving Mode S messages from the same aircraft. Mode S is somewhat of a precursor technology to ADS-B and includes the six hexadecimal digit “ICAO” code assigned to the aircraft, but does not include the lat/lon coordinates or other information. We calculate these coordinates for MLAT targets by timing when the signal arrives at the various participating receivers.

The tracks received and displayed from MLAT can be smooth, but typically are pretty janky and jagged depending on what position was calculated. A good point of evidence for that is the 1/4 mile westbound jog of the helicopter's flight path at 1:47:15Z. I don't believe we can accurately say the helicopter was necessarily turning right.

Also noted in the full video with the NTSB's briefing was that the helicopter was in a left roll at the time of the collision:

The Blackhawk pitch at the time of the collision was about 1/2 degree nose up, with a left roll of 1.6 degrees.

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RedSquirrel17@reddit

Thank you for this information. You are correct that there is no ADS-B data from the Black Hawk. The NTSB stated during the briefing that the helicopter was equipped with ADS-B Out but it was not transmitting. The reason for this has yet to be determined.

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railker@reddit

And thank you for writing up a great summary of the key points of a lot of new information learned from this press conference, very well laid out!

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TH3J4CK4L@reddit

Thank you for the summary.

Please note that the question of whether "circling" was heard by the Blackhawk crew, 2 minutes prior to the crash, is still being evaluated by the Recorders Group. FWIW, my ear, from the LiveATC recording, hears only a mumble for that word - but that doesn't impair my understanding of the transmission. Regardless, the rest of the sentence makes everything clear, and the Blackhawk crew reports traffic in sight...

The summary is ambiguous as to whether the rest of the sentence ("for runway 33") is present on the Blackhawk CVR. Did the Livestream clarify this?

Of course, we will wait and see if this detail becomes relevant in the final report.

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biggsteve81@reddit

Here is the link to Chairman Homendy's prepared remarks, including the timeline of events.

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railker@reddit

Another good note I think, considering the discussions about the Blackhawk being 'off course' or too far West from the routes on the chart:

On this chart, you'll see the routes they were generally following: Helicopter Route 1 to Helicopter Route 4. These routes are designated by the Federal Aviation Administration, or FAA, and although you see blue lines, there are no defined boundaries to these routes.

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salooski@reddit

Thanks for posting, very helpful