PAT25 Page: 4 of 6

BrogulT
February 07, 2025, 04:21:00 GMT
permalink Post: 11823381

Quote:

Originally Posted by Cobraguy

I've not read the entire chain of thoughts and comments, so please excuse me if my thinking has already been brought out:
Further, seems to me that the helicopter was reporting 200 feet via the IFF (transponder), probably from the AAU-32 Baro altimeter instrument in the cockpit.
.

We keep going back to the altitude, but even if a 100 foot discrepancy were relevant, the ATC playback shows PAT25 displaying "003" immediately before the collision. It had been previously showing 003, then went to 002 for a while and then back to 003 right as the traces intersect. What data is there that shows that the helo was transmitting 200 feet at the time of the collision? Where it was 15 seconds before the collision is irrelevant.

https://www.reddit.com/r/aircrashinv...radar_sources/

Of course, I think the whole altitude issue is a red herring and the concentration of attention on this "discrepancy" reduces the attention on other issues that aren't as easily "corrected".

Subjects ATC PAT25

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PPRuNeUser548247
February 07, 2025, 10:20:00 GMT
permalink Post: 11823511

The deactivation of the PAT25's ADS-B system meant that it was not broadcasting its position, making it invisible to systems that rely on ADS-B data for situational awareness, including those on AA534. There would be no signal from PAT25 to trigger TCAS alerts to pilots of AA5342. NTSB also said it was 'likely' PAT25 crew were wearing night-vision goggles, which have greatly reduced field of view, as little as 40 degrees

Quite extraordinary for a supposed 'recertification' flight.

Subjects AA5342 ADSB (All) NTSB PAT25 Situational Awareness TCAS (All)

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hoistop
February 07, 2025, 11:01:00 GMT
permalink Post: 11823555

Quote:

Originally Posted by The Brigadier

Yes, but their ATC transponder was obviously operating normally in C mode. That should be enough to show PAT25 on CRJ screen as traffic, even if no RA was given (bearing in mind, they were cca 300ft AGL) It is of course completelly unreasonable to expect that CRJ crew should see or even avoid the Blackhawk incoming from (slightly) right, as they were merely 20-ish seconds from touchdown and manually aligning with the runway. Also, I believe that operating ATC transponder on Blackhawk allowed for clear view on ATC screen and I wonder if there was no alarm triggered on ATC computers - they probably do have such guard software in operation on DCA?
In another midair collision report, that happened in July 2022 at NorthLas Vegas airport, NTSB put out this:
Interviews with personnel at the air traffic control tower indicated that staffing was deficient, and most staff were required to work mandatory overtime shifts, reaching an annual average of 400 to 500 hours of overtime per controller. According to the air traffic manager (ATM), the inadequate staffing had resulted in reduced training discissions, and the management team was unable to appropriately monitor employee performance. The ATM stated that everyone on the team was exhausted, and that work/life balance was non-existent. It is likely that the cumulative effects of continued deficient staffing, excessive overtime, reduced training, and inadequate recovery time between shifts took a considerable toll on the control tower workforce.
I wonder, how this situation is with DCA ATC service.
I am not trying to blame ATC either. He issued clearance to PAT25 to cross behind and asked (and got) confirmation for CRJ in sight twice. It seems quite clear that helicopter crew did not look at the same airplane that ATC was asking about.
What baffles me here is, that it was obvious a routine procedure to let helicopters cross active runway heading less than 2 miles from runway treshold, leaving practically zero margin for error. Backups, designed to catch pilots or ATC errors (TCAS and ATC alarms) cannot catch up in short time left if someone makes a mistake, so this arrangement as based on "see and avoid" concept, in the night, with many lights in the background and a fact, that other aircraft on collision course does not move relatively on the screen, but just grows bigger. Unfortunatelly, that dot on the screen that will kill you starts growing bigger only in the last few seconds.
If I would ask ATC to cross runway heading DAY VFR so close to runway treshold at my airport with incoming commercial traffic, I would be denied 100 times out of 100 attempts. (and probably called nuts).
My guess on this tragedy is, that thru the years, the system was trying to pack more and more aircraft in the same space and same infrastructure, by gradually squeezing margins and safegueards, until one day, Jenga tower collapsed.

Subjects AA5342 ADSB (All) ATC Blackhawk (H-60) CRJ DCA NTSB PAT25 See and Avoid Situational Awareness TCAS (All) VFR

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Capn Bloggs
February 07, 2025, 11:52:00 GMT
permalink Post: 11823587

Quote:

Originally Posted by The Brigadier

There would be no signal from PAT25 to trigger TCAS alerts to pilots of AA5342.

TCAS does not require, nor use, ADS-B information (yet). If the PAT had it's Mode C ON, the TCAS on the CRJ would give full warnings... if it was high enough, which it wasn't. However, the TCAS issued a Traffic Advisory "Traffic Traffic" as the CRJ passed through 500ft (as per the NTSB briefing).

Subjects AA5342 ADSB (All) CRJ NTSB PAT25 TCAS (All)

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51bravo
February 07, 2025, 13:24:00 GMT
permalink Post: 11823651

"wait" , for sure.
How? considering where they have been at the first briefing about the conflict, just about entering Washington Channel ?

I have learned here:

speed around 90kt min, when orbiting
hovering not a safe option at night over black water (despite lights left and right and everywhere else)
Washington Channel: 200 yards wide
plus golf course and Potomac: less 1 mile wide
runway ends 01 and 15
city to the left with stadions etc.

I really run out of an idea what ATC would clear if the PAT25 crew didnt ask for "visual separation"...

Last edited by 51bravo; 7th February 2025 at 13:42 .

Subjects ATC PAT25 Separation (ALL) Visual Separation

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Luc Lion
February 07, 2025, 14:19:00 GMT
permalink Post: 11823680

Quote:

Originally Posted by 51bravo

I really run out of an idea what ATC would clear if the PAT25 crew didnt ask for "visual separation"...

Maybe something like continue route RT1 up to Pennsylvania Avenue, then route RT2 to Woods Corner, then route RT3 to Wilson Bridge.
There is also route RT6 from Bolling to Woods Corner, but I don't think that the steep climb from Hains Point 200ft to Bolling 1400ft is reasonable.

Subjects ATC PAT25 Separation (ALL) Visual Separation

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YRP
February 07, 2025, 22:36:00 GMT
permalink Post: 11823982

Quote:

Originally Posted by The Brigadier

As someone mentioned above, ADS-B isn't used by/for TCAS. TCAS doesn't work below 500' for various reasons.

The recertification flight might specifically need to be at night. It might even specifically require NVG. I also wonder if both pilots would be on NVG or just one of the two.

Last edited by YRP; 7th February 2025 at 22:49 . Reason: Edited to sound 10% less grumpy

Subjects AA5342 ADSB (All) NTSB Night Vision Goggles (NVG) PAT25 Situational Awareness TCAS (All)

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BrogulT
February 08, 2025, 01:43:00 GMT
permalink Post: 11824068

Quote:

Originally Posted by 51bravo

I really run out of an idea what ATC would clear if the PAT25 crew didnt ask for "visual separation"...

There's a designated holding point on the route. IDK exactly what that means, but it must mean something, right?

The river is 4000 feet wide just south of that designated point. I imagine there is a procedure otherwise what would be the point?

The other option is that they would have to have the landing traffic go around.

Subjects ATC PAT25 Separation (ALL) Visual Separation

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Ant T
February 08, 2025, 10:23:00 GMT
permalink Post: 11824232

Quote:

Originally Posted by Lead Balloon

If I've read the chart legend correctly, that triangle at Hains Point is a "Non-Compulsory Reporting or Holding Point".
...

Interesting also that the legend clearly describes the \x93Route Altitudes\x94 as \x93Recommended\x94 (not compulsory), therefore PAT25 being at 300\x92 while not being recommended, was not breaking any rules.

Subjects PAT25

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BuzzBox
February 08, 2025, 11:26:00 GMT
permalink Post: 11824272

Quote:

Originally Posted by Ant T

Interesting also that the legend clearly describes the “Route Altitudes” as “Recommended” (not compulsory), therefore PAT25 being at 300’ while not being recommended, was not breaking any rules.

The route description on the chart says "ROUTE ALTITUDES ARE MAXIMUM". Routes 1 and 4 are described as follows:

Subjects PAT25

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Wide Mouth Frog
February 10, 2025, 18:56:00 GMT
permalink Post: 11825666

Quote:

Originally Posted by deltafox44

+1
I think many pilots would have made a mistake indentifying : seen from the helo, there are 3 aircraft in final, plus 1 on take-off, at the same bearing, how can you tell for sure which is the one "just south of Wilson Bridge" ?

Quote:

Originally Posted by spornrad

NYT has attempted a reconstruction of the visual picture from the Blackhawk at the time of the first traffic alert, with the CRJ just south of Wilson Bridge.
They could only later identify the correct light spot by following its trajectory according to their mental image of the approach to 33.

This simulation, if correct, is harrowing. The accident aircraft is actually almost superimposed over the following aircraft AA3130 at exactly the time of the tower's first notification of traffic to the helicopter. The helicopter's response is so quick, so reflexive. Then when the second notification is received, even though PAT25 knows he has just asked for visual separation and been granted he asks again, further suggestion that this is reflexive behavior.

At the same time the accident aircraft peels off to the right to swing around and line up to 33, thus taking his (smaller) lights out of the helicopter's direct line of vision and leaving 3130's (brighter) lights still heading to 01 to decoy the pilot. The reflexive nature of the helicopter's responses suggest to me that the full implication of 'circling to 33' in the tower's first call was missed, and also sort of implies that the helicopter could not conceive that following (nearly) the published heliroute could lead him into conflict with an aircraft on final. Me neither.

Quote:

NOTAM 5/1069 for DCA, valid from 07 Feb 0200 UTC until 31 March 2359 UTC

I'd push the expiry date of that one out a little.

Last edited by Senior Pilot; 10th February 2025 at 21:22 . Reason: Quote

Subjects Blackhawk (H-60) CRJ DCA New York Times PAT25 Separation (ALL) Visual Separation

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BFSGrad
February 11, 2025, 00:18:00 GMT
permalink Post: 11825784

Quote:

Originally Posted by deltafox44

The situation was actually more visually complicated. Screenshot below is about 5 seconds prior to collision with red arrow pointing at 5342 turning into 33. There are 5 aircraft on final for 1 with a 6th joining the parade. AAL 3130 is over the Wilson Bridge and as I recall, UAL 472 next with a couple more JIAs in the stack. Adding to the background against which PAT25 is target hunting is National Harbor with some lesser contribution from the Naval Research Lab and Blue Plains.

Subjects PAT25

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DIBO
February 11, 2025, 00:58:00 GMT
permalink Post: 11825797

Quote:

Originally Posted by BFSGrad

The situation was actually more visually complicated.

And I think you can drop the "visually".
For the ATCO, there wasn't only the flow of arrivals, but a good number of (no delay) departures, all this on intersecting runways and, not shown on the screenshot, in the seconds (a few dozens of...) prior to the accident, the ATCO was handling at least 3 helicopters (Mussel7 / Medevac / PAT25), even not counting the police helicopter working in the SW corner as depicted in the screenshot.

And all this on three* separate frequencies, not fully cross coupled, so TWR was receiving on several occasions, simultaneous/parallel incoming R/T calls (* based on info from other posters in both threads here on pprune & NTSB info - but I still have doubts PAT25 was on UHF, although 3 or 2 freq's, doesn't really matter in this accident's context)

And simulations by VASAviation and the likes, are heavily edited (as they correctly indicate in their comments), so they easily give the impression that traffic and R/T comm's were relatively light...

Subjects ATCO NTSB PAT25

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RetiredF4
February 11, 2025, 07:54:00 GMT
permalink Post: 11825889

Quote:

Originally Posted by DIBO

And all this on three* separate frequencies, not fully cross coupled, so TWR was receiving on several occasions, simultaneous/parallel incoming R/T calls (* based on info from other posters in both threads here on pprune & NTSB info - but I still have doubts PAT25 was on UHF, although 3 or 2 freq's, doesn't really matter in this accident's context)

And simulations by VASAviation and the likes, are heavily edited (as they correctly indicate in their comments), so they easily give the impression that traffic and R/T comm's were relatively light...

In the linked article after the first paragraph is a link to the ATC radio communication. I think it is unedited, the crash happens after17 minutes.

https://www.npr.org/2025/01/30/nx-s1...ntroller-radio

Subjects ATC NTSB PAT25

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airplanecrazy
February 11, 2025, 19:28:00 GMT
permalink Post: 11826281

Quote:

Originally Posted by SLFstu

I’m not sure your quoting FAA helicopter routes as having no defined centreline or width would strictly apply in DC versus what they wrote about the North Shore of Long Island route in NYC where they are required to be 1 mile off the shoreline. As shown on the published helo chart (DIBO’s post #863, and your little chart insert) and in writing (BuzzBox’s post #998) Route 4 directs traffic to track “via the east bank of the Potomac” from the Wilson Bridge to Anacostia River. If the impact point was 1000 feet or so (give or take some trig) from the east bank of a 3000 feet wide river at that point wouldn’t this mean that PAT25 was not only too high but off track too? Otherwise according to your graphic even at 200 feet max elevation, being that distance from the east bank any helicopter not maintaining visual separation could collide if an AC was still positioning itself from being low on the glideslope.

My understanding is that the FAA depicted width of a helicopter route is governed by the following doc: https://www.faa.gov/air_traffic/flig...2-complete.pdf . It specifies that on a fully printed chart the route should be 0.1 inches wide regardless of chart scale. The chart I pulled from was 1:125,000 scale (full chart size is 51x33 inch poster), which would mean the routes "appear" to be 125,000 * 0.1 / 12 = 1,042 ft wide. In the same FAA chart package https://aeronav.faa.gov/visual/12-26...-Wash_Heli.pdf , the third page is a "Washington Inset" with a scale of 1:62,500. In that inset the routes "appear" to be 62,500 * 0.1 /12 = 521 ft wide. Also, if you look at the centerlines of the routes depicted on those two pages (which I "drew in" below), they do not exactly match. For example, look at how the full chart shows the route going east of Hains Point while the inset shows it very close to Hains Point.

DCA Helicopter Routes

Given these chart differences, I wonder how far a helicopter can stray from the various depictions of a route before it is considered a pilot deviation? Perhaps the NTSB will give us some insight with their accident report.

Last edited by airplanecrazy; 14th February 2025 at 23:53 . Reason: Emphasize the route "appear"

Subjects DCA FAA NTSB PAT25 Route 4 Separation (ALL) Visual Separation

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SINGAPURCANAC
February 12, 2025, 17:30:00 GMT
permalink Post: 11826835

Quote:

Originally Posted by BFSGrad

I would like to ask if it is known number of aircraft at TWR Frequency( ies) at the moment of collision?
One ATCO, worked , at three separate frequency, three runways, 6 aircraft for arrival 01, one a/c 33, plus three helicopter, plus how many departures ( both active and approaching/crossing active runways) ?
Plus active estimate for a few aircraft more?
Ground vehicles, any?

Subjects ATCO PAT25

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BFSGrad
February 12, 2025, 22:17:00 GMT
permalink Post: 11827015

Quote:

Originally Posted by SINGAPURCANAC

Listening to the tower and helo local controller audio files, here\x92s what I come up with from shortly before up to the time of the accident:

Fixed wing
AAL1630, departed 1, waiting handoff to departure
JIA5305, holding short 1, #2
DAL832, holding short 1 #3
JIA5342, cleared to land 33
AAL3130, cleared to land 1
AAL472, cleared visual 1
JIA5347, cleared visual 1, requested 33

Rotary wing
PAT25
helo, Zone 4
helo, callsign Blackjack 1, freq change approved just prior
helo, callsign Muscle 12, handed off to ADW prior
helo, request Route 3, Zone 6
helo, Zone 7
Medevac AirCare helo, proceeding to Inova Fairfax

Some of the helo\x92s on above list may be duplicates due to poor audio quality.

At the time of the accident, runway 4/22 was not in use.

Subjects ATC ATCO PAT25

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DIBO
February 14, 2025, 21:03:00 GMT
permalink Post: 11828208

Quote:

Originally Posted by deltafox44

Just heard NTSB briefing. It seems that the scapegoat will not be any of the humans involved, nor even the procedures, but the altimeter system of the black hawk (a 100 ft discrepancy) and the radio ( they did not hear "circling" and "pass behind" )

(my bold in quote) well.... that doesn't surprise me.
For a couple of days now, was thinking about posting something on an "extra noise" I keep hearing in the R/T comms, when TWR gives the ' pass behind ' instruction. Was wondering whether TWR's Tx wasn't stepped over by someone.
My first impression was that the extra noise came from an radio call from a turbine helicopter (given the typical background noise often heard in radio calls from turbine helicopters). And was wondering if it wasn't PAT25 that started replying to TWR's first ' in sight? ' call, effectively blocking part of TWR's second call, the ' pass behind ' part of the instruction.

In attached mp3 (in .zip per forum attachment requirements) around 00:05 I hear this 'extra noise'.

Edit:
well, this seems to confirm my initial impression:

Quote:

Originally Posted by parabatix

Briefing the RT comms, NTSB stated that a portion of the ATC instruction to the BlackHawk to 'pass behind the CRJ' was received in the Blackhawk (according to the CVR), truncated due to the BlackHawk keying the mic at the same time. Apparently, the words 'pass behind the' were missing from the BlackHawk CVR.

Attached Files

KDCA1-Twr-Midair - PAT25 pass behind.zip (89.1 KB, 20 views)

Last edited by DIBO; 14th February 2025 at 21:07 . Reason: last posts with NTSB info seem to confirm my suspicion

Subjects ATC Blackhawk (H-60) CRJ NTSB PAT25 Pass Behind Pass Behind (All)

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DIBO
February 14, 2025, 23:10:00 GMT
permalink Post: 11828287

Quote:

Originally Posted by meleagertoo

On the cobntrary, it is vanishingly unlikely that the 60 crew even glanced at their baro alt. They were flying HEIGHT - that is AGL, on radalt and radalt alone. No helo ever flies at that sort of height by reference, even fleetingly, to bar-alt. That instrument is totally redundant in such a case (except for mode C reporting)

so I'm not sure what to think of this statement from the NTSB brief:

Quote:

Originally Posted by NTSB autogenerated transcript

14:40 the first term is Radio altitude
...
15:04 parameter is not the primary means the
15:07 pilots would have used to determine
15:08 their height during flight the pilots
15:10 are not typically navigating using radio
15:13 altitude it is often different from what
15:15 they see on their primary Al altimeters
15:18 the next term is barometric altitude
15:21 this is typically the altitude the
15:23 pilots would use while they were flying

As they also corrected some previous released information (like PAT25 was on V HF - I know, not really relevant, but it was incorrect when they stated UHF previously), I wouldn't be surprised if they have to come back on this " not using radalt " statement

Subjects NTSB PAT25

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Commando Cody
February 15, 2025, 05:36:00 GMT
permalink Post: 11828365

Quote:

Originally Posted by Lead Balloon

It appears from the NTSB's most recent press conference that the instruction "pass behind the CRJ" was not heard in the helo's CVR and, therefore by inference, not heard by the crew. Am I correct in assuming that there is no requirement to readback an instruction like that in the USA? ATC appeared not to expect one.

The Aeronautical Information Manual lists a number of instructions that should be read back, but there are none that must be read back (unless the controller specifically requests). "Pass behind..." is not even one of the "should" be read back instructions, so ATC wouldn't be bothered by not getting a read back. Frankly, if there was a requirement to fully read back all things like "Pass behind..." the frequency would be constantly full. In any case, whether PAT25 heard the "Pass behind" or not, it had already said that it was providing its own visual separation, so not hearing an instruction to pass behind does not take away the requirement to maintain separation.

Last edited by Commando Cody; 15th February 2025 at 07:45 . Reason: precision

Subjects ATC CRJ PAT25 Pass Behind Pass Behind (All) Separation (ALL) Visual Separation

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