February 02, 2025, 05:50:00 GMT
permalink Post: 11819530
That\x92s the kind of information that the NTSB will discover from interviews.
Subjects
ATC
CRJ
DCA
NTSB
Separation (ALL)
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February 02, 2025, 06:03:00 GMT
permalink Post: 11819532
Well, that's interesting. You seem to be saying that "the system" worked as designed? FDR notes immediately before your reply:
Did ATC do all of that? Having listened to the ATC comms (including the UHF) a few times, I believe they did, for the most part? They mentioned CRJ (of what use is mentioning the type at night, I have no idea, but they did), they mentioned where it was and where it was headed, and they received two acknowledgments...
So that means this collision occurred entirely within all established protocls?
These aircraft crashed, as per the system specifications.
So the system is, to put it plainly...FUBAR?
That's not good.
Did ATC do all of that? Having listened to the ATC comms (including the UHF) a few times, I believe they did, for the most part? They mentioned CRJ (of what use is mentioning the type at night, I have no idea, but they did), they mentioned where it was and where it was headed, and they received two acknowledgments...
So that means this collision occurred entirely within all established protocls?
These aircraft crashed, as per the system specifications.
So the system is, to put it plainly...FUBAR?
That's not good.
The procedures effectively abdicate separation responsibility to a single point of failure, where failure is not unlikely and, as a consequence of the airspace design, failure results in high probabilities of collision.
The difficulties of identifying a specific aircraft, at night, in a background of stationary and moving lights, when moving objects on a collision course will always appear stationary to each other, are well known, as are the probabilities of mis-identification. The airspace design 'squeezes' inbound aircraft and transiting helicopters to practicality the same altitude, when instrument and other tolerances are taken into consideration.
Subjects
ATC
CRJ
Separation (ALL)
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February 02, 2025, 07:24:00 GMT
permalink Post: 11819550
Well, that's interesting. You seem to be saying that "the system" worked as designed? FDR notes immediately before your reply:
Did ATC do all of that? Having listened to the ATC comms (including the UHF) a few times, I believe they did, for the most part? They mentioned CRJ (of what use is mentioning the type at night, I have no idea, but they did), they mentioned where it was and where it was headed, and they received two acknowledgments...
So that means this collision occurred entirely within all established protocls?
These aircraft crashed, as per the system specifications.
So the system is, to put it plainly...FUBAR?
That's not good.
Did ATC do all of that? Having listened to the ATC comms (including the UHF) a few times, I believe they did, for the most part? They mentioned CRJ (of what use is mentioning the type at night, I have no idea, but they did), they mentioned where it was and where it was headed, and they received two acknowledgments...
So that means this collision occurred entirely within all established protocls?
These aircraft crashed, as per the system specifications.
So the system is, to put it plainly...FUBAR?
That's not good.
Musings:
"The system" includes all of us that are involved in aviation at all levels, everyday. Thee are a lot of flights that go into DCA every day, each crew observing the same conditions, and conducting briefings of the arrivals, approaches and departures. Same out of LAX etc. How many of us, as stakeholders in the system have raised our concerns to the system by the means available, the ASRS, company safety reporting systems, the squadron SMS systems. How many safety managers have bothered to go and do an operational route survey/audit? Without our active participation, then we are relying on some person long retired who designed a procedure that survives to this point in time, and due to our collective indifference to the common users safety we remain broadly mute, until something falls off the perch. At this point we feign surprise, shock and some horror, yet, search inside, how many of us are surprised by this event, or Jeju Air in Muan, or the Russians shooting down yet another civil aircraft, Instead, we pontificate, (myself possibly more than most) and point the bone at all others in the system,
SMS systems only work if they have data that is meaningful. Each airline may seem to be swamped in data, that however is not the case for dealing with extremely low incidence, but high consequence events. There is not enough data generally to do a damned thing with, for just UAL, DAL, AAL etc or other operators. To be able to understand fully a system behavior there has to be adequate data, At present the only aggregated data of any note is that with NASA under the ASRS, and with ICAO at the reportable event level. Each ICAO state safety plan is supposed to provide data to the extent it can to its own community and to ICAO, and that is generally the last that is seen of the data. The airlines and operators dont get feedback, ICAO may or may not apply that data towards rule making, but that is years hence, and does not meet the needs of the user or the public today. Without the data being available to all, it is diminished in its utility. SMS systems have limited effectiveness that is IMHO glossed over universally, as actually getting data that is useful takes effort, and then evaluating that data takes critical analysis. By squandering the opportunity to have the data to evaluate, it should be no surprise that occasionally, we have SA-1, SA-2 and SA-3 type situational awareness failures of biblical proportions.
Aerospace suffers from frequent events that are normal in most respects. Functional resonance is a reasonable paradigm to assess how the system is really working, to give the system the understanding of how large the slip between assumptions and real system behavior is. The means of doing that is available from the flight data, and from operational audit aimed at understanding how expectations of process match with the real world.
Alternatively, we can sit back and blame the victims of the most recent mishaps, chasing those that should take responsibility for this, which to an extent falls on all of us that use the system and don't bother to raise concerns to the system.
Complacency works well though, until it doesn't.
Subjects
ATC
CRJ
DCA
ICAO
Situational Awareness
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February 02, 2025, 10:36:00 GMT
permalink Post: 11819671
What should have been the vertical separation? I'm just a lowly PPL holder, but I imagine if the CRJ was at 325 feet, even a ceiling of 200 feet is too high for the helicopter.
Not just from a collision perspective, but a wake turbulance issue.
And maybe more importantly, what should have been the horizontal separation? Surely it should have been at least 500 feet after the passing CRJ (not based on air law, just common sense). Clearly there was no horizontal or vertical separation in the end, but just how far off minimums was the helicopter? Seems nearly impossible to be that far off the expected flight path.
Not just from a collision perspective, but a wake turbulance issue.
And maybe more importantly, what should have been the horizontal separation? Surely it should have been at least 500 feet after the passing CRJ (not based on air law, just common sense). Clearly there was no horizontal or vertical separation in the end, but just how far off minimums was the helicopter? Seems nearly impossible to be that far off the expected flight path.
Dozens of posts back, I asked the question that many recent posts have been keying on... if everyone was where they were supposed to be, they would have passed one over the other with 150 feet of separation! In what world is that OK?
Can all these non-aviation pundits here please get it into their heads that just because the helilane has a cieling of 200ft and the glideslope is 325 or whatever it does not imply that helos can, would or might EVER be allowed to pass 125 ft under an aircraft on finals nor would any sane helo pilot (there are some!) do so. That would be insane, as surely this common sense you speak of should tell you? What's a lateral 500ft got to do with air law or anything else, ever? You're muddling completely unconnected and irrelevant matters. Have you not read/heard the ATC transcripts? Helos are not given clearance to and cannot cross until landing traffic is clear (as this helo one was told) - ie until it has passed unless the incoming is sufficiently far away for there to be no possible confliction.
How far off minimums (actually a maximum)? - you've already answered that question yourself. 125ft.
The insanity of this routing procedure is that in the event of an accidental horizontal incursion into the track of an inboud as happened here there is in theory only 125 ft of vertical clearance to prevent a disaster which is nowhere near enough of a safety margin. That route should have been, imho, at least 5-800ft or more above two dots up on the glideslope.
Once again, helicopters never, never ever come to a free air hover for separation purposes - this is a ridiculous concept for numerous reasons that are too long to go into here, and would be downright dangerous at night over a black hole at 200ft. They slow and orbit if they have to, maybe slow right down if wind direction and speed allows, but never hover.
I know not everyone here is experienced on helos but if so could they please refrain from speculating on operating procedures? All this guff about altimeter accuracy is completely irrelevant and has created a huge amount of unnecessaty noise. The aircraft was flying a visual sight-picture approach where an altimeter barely features at all and helos at low level, especially at night and over water do not use the baro altimeter. They exclusively refer to rad-alt.
Finally, all those who think a visual self-positioning clearance as employed in this case behind crossing traffic is somehow hazardous are completely incorrect. Once again, at Heathrow the helilane crosses 27 L and R thresholds at (iirc)1000ft. The only clearances given as you approach the boundary is to the effect of 'cross NOW (directly) over the threshold', 'hold (at a VRP clear N/S of the threshold)' or, having confirmed and read back landing traffic visual and identified the formula is repeated, 'after the landing traffic 2 miles cross behind'. It's perfectly safe as as it isn't done at the same height as the airliner but with a large vertcal clearance too.
btw, does Marine One fly this route?
Last edited by meleagertoo; 2nd February 2025 at 11:41 .
Subjects
ATC
CRJ
Hover
Separation (ALL)
Vertical Separation
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February 02, 2025, 11:38:00 GMT
permalink Post: 11819710
Mere SLF here - I work in risk management (in a different industry) and so have an interest here, along with a lifelong interest in aviation - fully ready to be modded if I'm talking out of turn!
I accept the point regarding the likely economic impact. However I think its worth making the point that in the context of that '16 years without a fatality' record. there have been a number of potentially serious near-misses on the ground (JBU at BOS, AAL/DAL at JFK, SWA/FDX at AUS, etc etc) that are indicative of a system operating beyond its capacity and implementing procedures that are deemed to be of an acceptable risk profile in order to stretch that capacity. It was fortunate that those previous incidents were narrowly avoided. Wednesday night was where that luck, sadly, ran out.
I accept the point regarding the likely economic impact. However I think its worth making the point that in the context of that '16 years without a fatality' record. there have been a number of potentially serious near-misses on the ground (JBU at BOS, AAL/DAL at JFK, SWA/FDX at AUS, etc etc) that are indicative of a system operating beyond its capacity and implementing procedures that are deemed to be of an acceptable risk profile in order to stretch that capacity. It was fortunate that those previous incidents were narrowly avoided. Wednesday night was where that luck, sadly, ran out.
Despite what's said almost universally by politicians and aviation authorities worldwide, the answers are driven and determined by politics, not the laws of physics and probabilities. "Safety is always our highest priority" is a meaningless but comforting sop for the public.
Ponder this question: If the POB the CRJ were senior politicians and important bureaucrats instead of the actual POB killed in this tragedy, would the investigation be carried out any differently, and its outcomes be any different, than if the POB were us nobodies?
I earnestly (perhaps naively) hope that the NTSB has and continues to have the corporate competence and the corporate integrity to investigate the circumstances of this tragedy, comprehensively, and to make frank and fearless findings and recommendations based on the objective facts and objective risks.
Subjects
ATC
CRJ
Close Calls
Findings
NTSB
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February 02, 2025, 13:52:00 GMT
permalink Post: 11819808
When flying we have a mental picture of what is going on around us. Sometimes that picture is defective. The helicopter pilots saw a stream of landing aircraft for runway 01. Their mental picture may well have been to slot between the arrivals they could see lined up for that runway. The controller asks the CRJ if he can circle round to 33, maybe missed in the Blackhawk cockpit. But in any case the right and then left turn to align with 33 would have made them harder to see for the helicopter particularly from the right seat where the commander more often sits in helicopters. Self evidently the helicopter pilots did not see the CRJ. They thought they did and reported so. The controller clearly thought that they could see it. But I suspect the circle manouevre took the CRJ further left and possibly behind where the helicopter crew were looking.
Subjects
ATC
Blackhawk (H-60)
CRJ
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February 02, 2025, 15:04:00 GMT
permalink Post: 11819846
I'm struggling to make sense of the numbers being bandied about here. Apparently the NTSB has said that the CRJ was at 375 feet,
But from the beginning, various plots have shown the collision occurring in mid-river. A little work with Google Earth will show that the extended 33 centre line reaches mid-river about 3,300 feet from the aimpoint of runway 33. A 3 degree glideslope and some trig will put it at 175 feet at that range, with obvious implications. 375 feet would be a big error with not much more than half a mile left to run.
What am I doing wrong?
Also, helicopter route 4 hugs the eastern bank of the Potomac until Goose Island and doesn't cross to the western bank until Wilson Bridge. So why did the Black Hawk perform a 45 degree right turn while still abeam DCA? (See, e.g., post #25) Was it intending to route direct to Fort Belvoir, ignoring the heli routes? (I think I've seen it was operating out of Joint Base Anacostia en route to Fort Belvoir, so the fact it was still abeam DCA must have been more than obvious.)
Puzzled.
But from the beginning, various plots have shown the collision occurring in mid-river. A little work with Google Earth will show that the extended 33 centre line reaches mid-river about 3,300 feet from the aimpoint of runway 33. A 3 degree glideslope and some trig will put it at 175 feet at that range, with obvious implications. 375 feet would be a big error with not much more than half a mile left to run.
What am I doing wrong?
Also, helicopter route 4 hugs the eastern bank of the Potomac until Goose Island and doesn't cross to the western bank until Wilson Bridge. So why did the Black Hawk perform a 45 degree right turn while still abeam DCA? (See, e.g., post #25) Was it intending to route direct to Fort Belvoir, ignoring the heli routes? (I think I've seen it was operating out of Joint Base Anacostia en route to Fort Belvoir, so the fact it was still abeam DCA must have been more than obvious.)
Puzzled.
Last edited by DespairingTraveller; 2nd February 2025 at 15:24 . Reason: edited to correct typo
Subjects
Blackhawk (H-60)
CRJ
DCA
NTSB
Route 4
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February 02, 2025, 15:07:00 GMT
permalink Post: 11819849
I don't think visual separation would relax the height altitude for the route?? If you listen a little longer request visual separation and visual separation approved were requested and given so matter of factly almost without thought? Only my opinions....
If the reports of NVG's being used in such airspace this could be a factor? Plus instead of "confirm you have the CRJ in sight" a "confirm you have the CRJ in your left 10 O'clock 3 miles insight?" But it's easy with hindsight!
If the reports of NVG's being used in such airspace this could be a factor? Plus instead of "confirm you have the CRJ in sight" a "confirm you have the CRJ in your left 10 O'clock 3 miles insight?" But it's easy with hindsight!
Subjects
CRJ
Night Vision Goggles (NVG)
Separation (ALL)
Visual Separation
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February 02, 2025, 16:35:00 GMT
permalink Post: 11819905
I know I'm fighting a losing battle but here goes.....
What you are doing wrong is making guesses based on incomplete/inaccurate data that is in the public domain.
Assuming the NTSB figure of 375ft is correct, you still need more info for it to mean anything. Was that the AGL, AMSL or SPS height/altitude?
How accurate are the 'various plots' that indicate the collision occurred mid-river? They may be right; they may not be.
Was the CRJ on final or was it still positioning to final? If it wasn't on final then the trigonometric calculations of what height it should be at might not be correct.
What official evidence is there that the Blackhawk made a 45 degree turn, or could that be a data error in the publicly available information?
In summary what I am saying is that, despite all of the internet sleuths plotting tracking data, none of it is official and it is all subject to various errors. Whilst interesting to form an understanding of the circumstances, it can't be assumed to be accurate to within a few feet (vertically or laterally).
That 1-2 feet error would be a theoretical accuracy. The readout in the cockpit would be subject to significant errors during turns/pitch changes etc; without knowing the exact installation on a Blackhawk, it might also unlock based on the surface conditions. More importantly, the ATC instructions would probably be based on an altimeter setting and not Rad Alt.
How would that have worked in this scenario? Who do you think should have been directed by TCAS to do what? Does the Blackhawk even have TCAS?
I'm struggling to make sense of the numbers being bandied about here. Apparently the NTSB has said that the CRJ was at 375 feet,
But from the beginning, various plots have shown the collision occurring in mid-river. A little work with Google Earth will show that the extended 33 centre line reaches mid-river about 3,300 feet from the aimpoint of runway 33. A 3 degree glideslope and some trig will put it at 175 feet at that range, with obvious implications. 375 feet would be a big error with not much more than half a mile left to run.
What am I doing wrong?
Also, helicopter route 4 hugs the eastern bank of the Potomac until Goose Island and doesn't cross to the western bank until Wilson Bridge. So why did the Black Hawk perform a 45 degree right turn while still abeam DCA? (See, e.g., post #25) Was it intending to route direct to Fort Belvoir, ignoring the heli routes? (I think I've seen it was operating out of Joint Base Anacostia en route to Fort Belvoir, so the fact it was still abeam DCA must have been more than obvious.)
Puzzled.
But from the beginning, various plots have shown the collision occurring in mid-river. A little work with Google Earth will show that the extended 33 centre line reaches mid-river about 3,300 feet from the aimpoint of runway 33. A 3 degree glideslope and some trig will put it at 175 feet at that range, with obvious implications. 375 feet would be a big error with not much more than half a mile left to run.
What am I doing wrong?
Also, helicopter route 4 hugs the eastern bank of the Potomac until Goose Island and doesn't cross to the western bank until Wilson Bridge. So why did the Black Hawk perform a 45 degree right turn while still abeam DCA? (See, e.g., post #25) Was it intending to route direct to Fort Belvoir, ignoring the heli routes? (I think I've seen it was operating out of Joint Base Anacostia en route to Fort Belvoir, so the fact it was still abeam DCA must have been more than obvious.)
Puzzled.
Assuming the NTSB figure of 375ft is correct, you still need more info for it to mean anything. Was that the AGL, AMSL or SPS height/altitude?
How accurate are the 'various plots' that indicate the collision occurred mid-river? They may be right; they may not be.
Was the CRJ on final or was it still positioning to final? If it wasn't on final then the trigonometric calculations of what height it should be at might not be correct.
What official evidence is there that the Blackhawk made a 45 degree turn, or could that be a data error in the publicly available information?
In summary what I am saying is that, despite all of the internet sleuths plotting tracking data, none of it is official and it is all subject to various errors. Whilst interesting to form an understanding of the circumstances, it can't be assumed to be accurate to within a few feet (vertically or laterally).
Regarding UH-60L altimeters:
All UH-60 A and L Army aircraft incorporated the APN 209 radar altimeter. Our Sikorsky tech fellow for Avioics/electronis reports the accuracy in this area is 1-2 feet. The radar altimeter position in the instrument panel is just to the right of the attitude indicator and its top matches the top of the attitude indicator. The barometric altimeter is immediately below it.
Both pilots have the same setup.
All UH-60 A and L Army aircraft incorporated the APN 209 radar altimeter. Our Sikorsky tech fellow for Avioics/electronis reports the accuracy in this area is 1-2 feet. The radar altimeter position in the instrument panel is just to the right of the attitude indicator and its top matches the top of the attitude indicator. The barometric altimeter is immediately below it.
Both pilots have the same setup.
Instead of no RA below 500ft (or whatever the floor is), how about telling one conflict to climb and the other one to \x91not climb\x92? \x91Not climb\x92 could then be understood (and trained) to mean \x91descend a little, terrain/aircraft/wx permitting or fly level\x92. Lots of ifs and buts, spurious warnings, limitations for when 3 or more conflicts, TCAS vs. GPWS considerations etc. but perhaps worth a thought.
Subjects
ATC
Barometric Altimeter
Blackhawk (H-60)
CRJ
DCA
NTSB
Radar
Route 4
TCAS (All)
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February 02, 2025, 16:54:00 GMT
permalink Post: 11819920
I know I'm fighting a losing battle but here goes.....
What you are doing wrong is making guesses based on incomplete/inaccurate data that is in the public domain.
Assuming the NTSB figure of 375ft is correct, you still need more info for it to mean anything. Was that the AGL, AMSL or SPS height/altitude?
How accurate are the 'various plots' that indicate the collision occurred mid-river? They may be right; they may not be.
Was the CRJ on final or was it still positioning to final? If it wasn't on final then the trigonometric calculations of what height it should be at might not be correct.
What official evidence is there that the Blackhawk made a 45 degree turn, or could that be a data error in the publicly available information?
In summary what I am saying is that, despite all of the internet sleuths plotting tracking data, none of it is official and it is all subject to various errors. Whilst interesting to form an understanding of the circumstances, it can't be assumed to be accurate to within a few feet (vertically or laterally).
That 1-2 feet error would be a theoretical accuracy. The readout in the cockpit would be subject to significant errors during turns/pitch changes etc; without knowing the exact installation on a Blackhawk, it might also unlock based on the surface conditions. More importantly, the ATC instructions would probably be based on an altimeter setting and not Rad Alt.
How would that have worked in this scenario? Who do you think should have been directed by TCAS to do what? Does the Blackhawk even have TCAS?
What you are doing wrong is making guesses based on incomplete/inaccurate data that is in the public domain.
Assuming the NTSB figure of 375ft is correct, you still need more info for it to mean anything. Was that the AGL, AMSL or SPS height/altitude?
How accurate are the 'various plots' that indicate the collision occurred mid-river? They may be right; they may not be.
Was the CRJ on final or was it still positioning to final? If it wasn't on final then the trigonometric calculations of what height it should be at might not be correct.
What official evidence is there that the Blackhawk made a 45 degree turn, or could that be a data error in the publicly available information?
In summary what I am saying is that, despite all of the internet sleuths plotting tracking data, none of it is official and it is all subject to various errors. Whilst interesting to form an understanding of the circumstances, it can't be assumed to be accurate to within a few feet (vertically or laterally).
That 1-2 feet error would be a theoretical accuracy. The readout in the cockpit would be subject to significant errors during turns/pitch changes etc; without knowing the exact installation on a Blackhawk, it might also unlock based on the surface conditions. More importantly, the ATC instructions would probably be based on an altimeter setting and not Rad Alt.
How would that have worked in this scenario? Who do you think should have been directed by TCAS to do what? Does the Blackhawk even have TCAS?
Subjects
ATC
Blackhawk (H-60)
CRJ
NTSB
TCAS (All)
TCAS RA
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February 02, 2025, 17:19:00 GMT
permalink Post: 11819940
I know I'm fighting a losing battle but here goes.....
What you are doing wrong is making guesses based on incomplete/inaccurate data that is in the public domain.
Assuming the NTSB figure of 375ft is correct, you still need more info for it to mean anything. Was that the AGL, AMSL or SPS height/altitude?
How accurate are the 'various plots' that indicate the collision occurred mid-river? They may be right; they may not be.
Was the CRJ on final or was it still positioning to final? If it wasn't on final then the trigonometric calculations of what height it should be at might not be correct.
What official evidence is there that the Blackhawk made a 45 degree turn, or could that be a data error in the publicly available information?
In summary what I am saying is that, despite all of the internet sleuths plotting tracking data, none of it is official and it is all subject to various errors. Whilst interesting to form an understanding of the circumstances, it can't be assumed to be accurate to within a few feet (vertically or laterally).
What you are doing wrong is making guesses based on incomplete/inaccurate data that is in the public domain.
Assuming the NTSB figure of 375ft is correct, you still need more info for it to mean anything. Was that the AGL, AMSL or SPS height/altitude?
How accurate are the 'various plots' that indicate the collision occurred mid-river? They may be right; they may not be.
Was the CRJ on final or was it still positioning to final? If it wasn't on final then the trigonometric calculations of what height it should be at might not be correct.
What official evidence is there that the Blackhawk made a 45 degree turn, or could that be a data error in the publicly available information?
In summary what I am saying is that, despite all of the internet sleuths plotting tracking data, none of it is official and it is all subject to various errors. Whilst interesting to form an understanding of the circumstances, it can't be assumed to be accurate to within a few feet (vertically or laterally).
Similarly, given that both aircraft did sadly end up in the river, there's limited margin for error in the position of the impact as well. The Potomac is narrow near DCA as a glance at a chart will show.
Anyway, I have no expectation of solving anything. Just trying to understand the information that's out there.
Subjects
Blackhawk (H-60)
CRJ
DCA
NTSB
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February 02, 2025, 17:33:00 GMT
permalink Post: 11819950
It could have instructed the CRJ to climb (meaning initiate go-around immediately) and the heli to ‘not climb’ (meaning descend if practicable). Or it could have instructed heli to climb and CRJ to not climb (meaning continue descent or level and look out). I am saying that tech is there in principle and the 500ft RA floor was decided on 20-30y ago, probably to limit complexity and risk of dangerous RAs, but that this limitation could be revisited in future, especially with lots more data and modelling capability to assess.
TCAS RA have inhibits at low altitude, or do you have some other system in mind?
Subjects
CRJ
TCAS (All)
TCAS RA
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February 02, 2025, 17:43:00 GMT
permalink Post: 11819955
According to the NTSB chief yesterday, the CRJ was at 325 ft plus or minus 25 feet, so not sure where the 375ft comes from?
Subjects
CRJ
NTSB
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February 02, 2025, 19:00:00 GMT
permalink Post: 11820010
Do you honestly think that you've just thought of that and the system designers haven't?
In relation to your earlier response to my previous comment, how can the system tell someone to 'remain level' when that aircraft doesn't have TCAS? I am not sure of the Blackhawk fit, but I would be pretty surprised if it has TCAS fitted.
One of the main reasons that TCAS alerts are inhibited at low altitude is to avoid distraction during the landing phase, in an area that has a high traffic density and a high probably of nuisance alerts. The system would constantly be giving RAs and people would be going around and deviating all over the place. Even if just TAs were left active then it would be going off all the time, and we would be having the same conversation about becoming blase to the warnings as we are about the repetitive conflict alerts that were being given to the LC.
Getting TCAS to give RAs on final is not the solution in my opinion.
In relation to your earlier response to my previous comment, how can the system tell someone to 'remain level' when that aircraft doesn't have TCAS? I am not sure of the Blackhawk fit, but I would be pretty surprised if it has TCAS fitted.
One of the main reasons that TCAS alerts are inhibited at low altitude is to avoid distraction during the landing phase, in an area that has a high traffic density and a high probably of nuisance alerts. The system would constantly be giving RAs and people would be going around and deviating all over the place. Even if just TAs were left active then it would be going off all the time, and we would be having the same conversation about becoming blase to the warnings as we are about the repetitive conflict alerts that were being given to the LC.
Getting TCAS to give RAs on final is not the solution in my opinion.
And inhibition floor could still be greater than zero - say 100-200ft?
Separately, is it correct to say that CRJ were on final, or were they perhaps still turning onto final?
Subjects
Blackhawk (H-60)
CRJ
TCAS (All)
TCAS RA
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February 02, 2025, 19:19:00 GMT
permalink Post: 11820026
I have 2 questions regarding DCA ATC procedures.(they are probably related)
1) If PAT25 had said they were unable to identify the inbound CRJ, how would ATC have dealt with it?
2) Why was PAT25 requesting \x93Visual Separation\x94? What advantage did that give to PAT25?
1) If PAT25 had said they were unable to identify the inbound CRJ, how would ATC have dealt with it?
2) Why was PAT25 requesting \x93Visual Separation\x94? What advantage did that give to PAT25?
Subjects
ATC
CRJ
DCA
PAT25
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February 02, 2025, 19:56:00 GMT
permalink Post: 11820054
I have 2 questions regarding DCA ATC procedures.(they are probably related)
1) If PAT25 had said they were unable to identify the inbound CRJ, how would ATC have dealt with it?
2) Why was PAT25 requesting \x93Visual Separation\x94? What advantage did that give to PAT25?
1) If PAT25 had said they were unable to identify the inbound CRJ, how would ATC have dealt with it?
2) Why was PAT25 requesting \x93Visual Separation\x94? What advantage did that give to PAT25?
Subjects
ATC
CRJ
DCA
PAT25
Separation (ALL)
Visual Separation
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February 02, 2025, 20:28:00 GMT
permalink Post: 11820083
The CRJ700 was likely approaching Runway 33 at a heading of approximately 330 degrees, meaning it was moving northwest. The UH-60 Black Hawk may have been traveling at a heading roughly 240 to 270 degrees (west or southwest), which would place it on a near-perpendicular course relative to the plane.
If the aircraft were at a close to 90-degree intersection, then the CRJ700 would have been moving across the field of vision right in front of the helicopter, thus making the collision all the more perplexing, not withstanding night vision goggles (if indeed worn) interfere with depth perception and can reduce field of view to as low as 40\xb0. Of course there also remains the reported disparity in flying height, with the UH-60 100 feet above it's flight ceiling
If the aircraft were at a close to 90-degree intersection, then the CRJ700 would have been moving across the field of vision right in front of the helicopter, thus making the collision all the more perplexing, not withstanding night vision goggles (if indeed worn) interfere with depth perception and can reduce field of view to as low as 40\xb0. Of course there also remains the reported disparity in flying height, with the UH-60 100 feet above it's flight ceiling
Subjects
Blackhawk (H-60)
CRJ
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February 02, 2025, 21:03:00 GMT
permalink Post: 11820111
The CRJ700 was likely approaching Runway 33 at a heading of approximately 330 degrees, meaning it was moving northwest. The UH-60 Black Hawk may have been traveling at a heading roughly 240 to 270 degrees (west or southwest), which would place it on a near-perpendicular course relative to the plane.
If the aircraft were at a close to 90-degree intersection, then the CRJ700 would have been moving across the field of vision right in front of the helicopter, thus making the collision all the more perplexing, not withstanding night vision goggles (if indeed worn) interfere with depth perception and can reduce field of view to as low as 40\xb0. Of course there also remains the reported disparity in flying height, with the UH-60 100 feet above it's flight ceiling
If the aircraft were at a close to 90-degree intersection, then the CRJ700 would have been moving across the field of vision right in front of the helicopter, thus making the collision all the more perplexing, not withstanding night vision goggles (if indeed worn) interfere with depth perception and can reduce field of view to as low as 40\xb0. Of course there also remains the reported disparity in flying height, with the UH-60 100 feet above it's flight ceiling
I can't access the METAR history any more, but I think it was 270V330 with gusts above 20kts. With the helo showing a groundspeed of 80kts on the radar trace, a westerly wind of just 12kts would give 9 degrees of drift and therefore a helo heading of 196, putting the CRJ just outside the 20 degree semi-angle of NVG with 40 degree field of view if the pilots were looking straight ahead.
If anyone can supply the METAR info (there was a report just 10mins after the accident), I'll update my radar diagram with the helo heading and a superimposed field of view. (Edit: done at #729 )
Last edited by Easy Street; 3rd February 2025 at 02:04 .
Subjects
Blackhawk (H-60)
CRJ
Night Vision Goggles (NVG)
Radar
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February 02, 2025, 21:47:00 GMT
permalink Post: 11820135
Subjects
CRJ
TCAS (All)
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February 02, 2025, 21:47:00 GMT
permalink Post: 11820137
Subjects
ADSB (All)
CRJ
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