Posts about: "Vertical Separation" [Posts: 73 Page: 4 of 4]ΒΆ

ATC Watcher
June 25, 2025, 11:25:00 GMT
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Post: 11910447
action is taking place with changes on the routes :
The FAA has made significant changes to helicopter flight zones south of the airport, effective June 12. They are now restricted from flying over a large portion of the Potomac River and have been moved further away from fixed wing arrival and departure paths. There’s a new route called the ‘Broad Creek Transition’ which provides greater vertical separation for heli transits south of the field. It is the latest in a series of safety improvements since January’s tragic collision.
(source Ops group Briefing ).

Subjects FAA  Separation (ALL)  Vertical Separation

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MechEngr
July 31, 2025, 19:18:00 GMT
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Post: 11931506
Depending on radalt for this flight mode is a problem when flying over buildings or terrain when one wants to maintain an absolute altitude relative to a common datum. If done perfectly radalt would be hammering back and forth with every chimney and tree and park and car. I'm sure they use smoothing to give something for the crew to read, but it doesn't tell how high the terrain is that the measurement is made from - it only reports clearance to the terrain when one wants clearance to other aircraft.

For TF/TA radalt is the go-to instrument, but for coordinating multiple aircraft to maintain vertical separation, barometric altitude is more suitable. The problem being that barometric altimeters are subject to a lot of measurement and reporting errors.

I am sure that GPS-RTK could be used to fix the absolute altitude with great precision, but I am also sure that depending on an easily denied measurement source on a military aircraft is not going happen.

The correct solution for operating in a civilian airspace is to use ADS-B In/Out for all manned aircraft to provide appropriate and timely situational awareness. While ADS-B is also subject to denial, it offers far greater benefit in civilian airspace over GPS-RTK in that it tells the pilots where all the other aircraft are rather than simply being more precise about where their own aircraft is.

It is clear that the helicopter crew not knowing where the passenger jet was was the primary cause of the collision.

Arguments about the error in the altimeter readings are suitable to emphasize that depending on them in a crowded airspace is a fool's choice and should have been spotted a long time ago as insufficient to provide clearance.

Subjects ADSB (All)  Separation (ALL)  Situational Awareness  Vertical Separation

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MechEngr
July 31, 2025, 23:36:00 GMT
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Post: 11931584
No matter, radalt only gives the altitude above some actual thing, not a shared pressure altitude that all air vehicles can agree on. AA5342 was not on a radalt path. AA5342 was flying over buildings.

EDIT: I also appreciate the arriving jet was on a geometric glide slope and that radalt under the glideslope could have been sufficient, but if one is expecting that vertical separation is sufficient then there needs to be certainty to that altitude and clearly that isn't possible on barometric altimeter and should never have been accepted by anyone.

Last edited by MechEngr; 1st August 2025 at 05:39 .

Subjects AA5342  Barometric Altimeter  Separation (ALL)  Vertical Separation

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andihce
August 10, 2025, 05:00:00 GMT
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Post: 11936009
There have been a number of references above to the woefully inadequate vertical separation provided between helicopter Route 4 and the approach to Runway 33. Given altimeter errors (expected and maybe not so expected) in the helicopter, a helicopter flying high (and possibly offset sideways towards the end of Runway 33) and an aircraft maybe low on approach, there really wasn’t any guaranteed separation.

I strikes me that, from my layman’s point of view, that this is the primary and gaping hole (among numerous others) in the Swiss cheese here.

At the same time, I get the sense that no controller was ever going to intentionally permit a helicopter to pass directly under an approaching aircraft and challenge that limited clearance.

My question is, should this have been (or was it?) formalized as an ATC procedure? Because if this had been proceduralized, I find it hard to believe that just nighttime VFR separation would have been found acceptable in that environment. Rather I would think that lateral separation should have been actively managed by ATC.

For one thing, with the CRJ (or whatever aircraft) pilots making a late switch to 33, turning to line up with the runway, etc., they may not have had the bandwidth to scan for a possibly conflicting helicopter, if they could even have seen it from their cockpit. (IIRC from the inquiry, the NTSB will be investigating that last point.)

I don’t know how difficult it may have been for the helicopter to see the CRJ, but the simple fact is that they did not.



On another subject, one thing that struck me from the inquiry was that the helicopter pilot apparently had very limited recent flight time, yet was assigned a challenging check ride.

This contrasted with the testimony of the leader (?) of one of the local Medivac groups, who discussed how much more experience he and his pilots had flying in that challenging environment (and often single-pilot ops at that).

Is the Army not providing adequate training and flight time to ensure their pilots can operate safely in those conditions?

Last edited by andihce; 10th August 2025 at 06:44 . Reason: clarification

Subjects ATC  CRJ  NTSB  Route 4  Separation (ALL)  VFR  Vertical Separation

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aox
August 10, 2025, 06:10:00 GMT
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Post: 11936017
Originally Posted by andihce
There have been a number of references above to the woefully inadequate vertical separation provided between helicopter Route 4 and the approach to Runway 33. Given altimeter errors (expected and maybe not so expected) in the helicopter, a helicopter flying high (and possibly offset sideways towards the end of Runway 33) and an aircraft maybe low on approach, there really wasn\x92t any guaranteed separation.

I strikes me that, from my layman\x92s point of view, that this is the primary and gaping hole (among numerous others) in the Swiss cheese here.

At the same time, I get the sense that no controller was ever going to allow a helicopter to pass directly under an approaching aircraft and challenge that limited clearance.

My question is, should this have been (or was it?) formalized as an ATC procedure? Because if this had been proceduralized, I find it hard to believe that just nighttime VFR separation would have been found acceptable in that environment. Rather I would think that lateral separation should have been actively managed by ATC.

For one thing, with the CRJ (or whatever aircraft) pilots making a late switch to 33, turning to line up with the runway, etc., they may not have had the bandwidth to scan for a possibly conflicting helicopter, if they could even have seen it from their cockpit. (IIRC from the inquiry, the NTSB will be investigating that last point.)

I don\x92t know how difficult it may have been for the helicopter to see the CRJ, but the simple fact is that they did not.
I wouldn't bother explaining it to laymen as a hole in cheese. In layman's terms it's the same as having two busy roads cross, and no traffic lights.

And to stick with motoring analogies, some of us are used to considering that at a junction another vehicle can be partly obscured by a pillar for one eye, and in the blind spot of our other eye, so we might move our head sideways to help check better. Some aircraft have more windscreen pillars (this helicopter has four) so the aircraft in a constant relative position - which is the one that is the collision risk - may stay behind a pillar unless we move our head.

Subjects ATC  CRJ  NTSB  Route 4  Separation (ALL)  VFR  Vertical Separation

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ignorantAndroid
August 10, 2025, 06:48:00 GMT
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Post: 11936029
Originally Posted by andihce
There have been a number of references above to the woefully inadequate vertical separation provided between helicopter Route 4 and the approach to Runway 33. Given altimeter errors (expected and maybe not so expected) in the helicopter, a helicopter flying high (and possibly offset sideways towards the end of Runway 33) and an aircraft maybe low on approach, there really wasn\x92t any guaranteed separation.

I strikes me that, from my layman\x92s point of view, that this is the primary and gaping hole (among numerous others) in the Swiss cheese here.

At the same time, I get the sense that no controller was ever going to allow a helicopter to pass directly under an approaching aircraft and challenge that limited clearance.

My question is, should this have been (or was it?) formalized as an ATC procedure? Because if this had been proceduralized, I find it hard to believe that just nighttime VFR separation would have been found acceptable in that environment. Rather I would think that lateral separation should have been actively managed by ATC.
It's simple; the altitude restriction was never intended to be the sole method of separation. At most, it was an additional layer of protection. The controller wouldn't have cleared the Blackhawk to continue if they hadn't said they had the traffic in sight. But they did say that, whether it was true or not. ATC is a service provided to pilots, not an authority. Pilot-applied visual separation essentially overrides any procedure used by ATC. When you say "Traffic in sight," you are saying "I don't need your help maintaining separation, I have it under control and I take full responsibility."

Originally Posted by andihce
For one thing, with the CRJ (or whatever aircraft) pilots making a late switch to 33, turning to line up with the runway, etc., they may not have had the bandwidth to scan for a possibly conflicting helicopter, if they could even have seen it from their cockpit. (IIRC from the inquiry, the NTSB will be investigating that last point.)
The IFR aircraft wouldn't be required to have the traffic in sight.

Subjects ATC  Blackhawk (H-60)  CRJ  IFR  NTSB  Route 4  Separation (ALL)  Traffic in Sight  VFR  Vertical Separation  Visual Separation

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Capn Bloggs
October 16, 2025, 09:20:00 GMT
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Post: 11970787
What load of codswallop. Now we'll have every dogsbody pilot peering at their ADS-B In screens and asking ATC "is that return going to miss us?". TCAS does not require ADS-B, only a transponder (Mode S best). ADS-B In in busy CTAs/zones will be a distracting nightmare for crews.

Every pax jet is separated by SIDs and STARs, with either lateral and/or vertical separation. That is what is required here with the choppers. Playing TCAS dodgem-cars below 1000ft when you're trying to land is not the way to go.

Point 3 is the only one that makes any real sense. The rest sound good only to the great-unwashed.

Subjects ADSB (All)  ADSB In  ATC  Separation (ALL)  TCAS (All)  Vertical Separation

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WillowRun 6-3
October 16, 2025, 16:07:00 GMT
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Post: 11971014
Originally Posted by Capn Bloggs
What load of codswallop. Now we'll have every dogsbody pilot peering at their ADS-B In screens and asking ATC "is that return going to miss us?". TCAS does not require ADS-B, only a transponder (Mode S best). ADS-B In in busy CTAs/zones will be a distracting nightmare for crews.

Every pax jet is separated by SIDs and STARs, with either lateral and/or vertical separation. That is what is required here with the choppers. Playing TCAS dodgem-cars below 1000ft when you're trying to land is not the way to go.

Point 3 is the only one that makes any real sense. The rest sound good only to the great-unwashed.
As a non-technical poster on this forum I sure as shucks won't comment on the ADS-B content of the proposed legislation. But point 4 of the summary:
"Directs the Army OIG to initiate a safety coordination audit. The Army Inspector General has declined to voluntarily review the Army's aviation safety practices. The Inspector General would conduct an independent review of the Army's approach to safety."

Why does this not make real sense?

The NTSB will very likely (undoubtedly, I think) include, in its report, quite extensive findings about the Army's operations. It was at least very unusual, if not unprecedented, for the NTSB to issue urgent recommendations to FAA in the immediate aftermath of January 29 with regard to use of the helicopter routes. On these facts, why is it not sensible to require the Army to undergo an IG review?

Although without a service record, I do generally understand the idea that the Army's task and purpose is lethality, at least in the meaning of that term before the assemblage at Quantico earlier this fall. Surely operating in domestic airspace doesn't make safety irrelevant "becasue lethality", does it?

One other aspect of this tragic and from many perspectives senseless midair collision is that very dedicated professional people in the aviation field are going to have their respective actions and failures to act in the events of January 29 scrutinized in the most harshly critical light in a courtroom. Bluntly, their performance will be trashed - the Army pilots, one or more controllers, and as discussed recently on this thread, the airline aviators too. On these facts, and hoping that reasonable minds may differ, I think the IG review isn't just a sensible idea, it's a necessity. It is something owed to those people, who are not going to speak up in their defense, or in their eternal regrets, from the great beyond. The least the United States can do is to find out what to do better. I'll work for the IG project, gratis, .... if they'd take me.

Subjects ADSB (All)  ADSB In  ATC  FAA  Findings  NTSB  Separation (ALL)  TCAS (All)  Vertical Separation

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island_airphoto
October 18, 2025, 03:44:00 GMT
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Post: 11971880
Originally Posted by Capn Bloggs
What load of codswallop. Now we'll have every dogsbody pilot peering at their ADS-B In screens and asking ATC "is that return going to miss us?". TCAS does not require ADS-B, only a transponder (Mode S best). ADS-B In in busy CTAs/zones will be a distracting nightmare for crews.

Every pax jet is separated by SIDs and STARs, with either lateral and/or vertical separation. That is what is required here with the choppers. Playing TCAS dodgem-cars below 1000ft when you're trying to land is not the way to go.

Point 3 is the only one that makes any real sense. The rest sound good only to the great-unwashed.
I 100% disagree. ADS-B, among other things, lets YOU see who is going to come close to you without asking ATC what they think about it.

Subjects ADSB (All)  ADSB In  ATC  Separation (ALL)  TCAS (All)  Vertical Separation

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scard08
December 13, 2025, 03:58:00 GMT
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Post: 12004467
I've been reading this thread for many months, and there were people in it (pilots and ATC) saying nothing would have changed if ADS-B Out was enabled in the helo. Isn't that what the House bill is trying to require? Politicians (and senior staff of federal agencies are certainly politicians) will produce all kinds of videos about all kinds of things, but does anyone in the industry think this matters? From what I have read, the problem was the lack of vertical separation between helo route 4 and the descent into 033, not the lack of data exchange. This feels like "we are going to do something" theatre.

Subjects ADSB (All)  ADSB Out  ATC  Route 4  Separation (ALL)  Vertical Separation

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WillowRun 6-3
December 13, 2025, 04:41:00 GMT
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Post: 12004472
Originally Posted by scard08
I've been reading this thread for many months, and there were people in it (pilots and ATC) saying nothing would have changed if ADS-B Out was enabled in the helo. Isn't that what the House bill is trying to require? Politicians (and senior staff of federal agencies are certainly politicians) will produce all kinds of videos about all kinds of things, but does anyone in the industry think this matters? From what I have read, the problem was the lack of vertical separation between helo route 4 and the descent into 033, not the lack of data exchange. This feels like "we are going to do something" theatre.
The NTSB has not said, and Chairwoman Homendy's letter does not say, that lack of ADS-B Out was the central cause of the accident. Without going through the whole thread again, as far as I recall no one has even argued, let alone persuasively asserted, that lack of ADS-B Out caused the accident. Any even mostly attentive reading of the thread would lead one to conclude that there were several big problems with the "situation" on the night of the accident. Just picking the one easiest for a non-aircrew to comprehend, the difficulty of discerning different objects, in the air and on the ground, at night and at low altitudes, particularly against the background of city lights, was a factor. No one has claimed lack of ADS-B Out made it a factor nor has anyone claimed that having ADS-B Out would remove it as a factor in given situations.

The argument that the NTSB Chair and the Congressional people who are opposed have heard some imperative to "don't just sit there, do something" is a straw man, imo.

But taking it with more credence than it seems to deserve, how do you explain the absence of much, or really any, opposition to the NTSB's recommendation issued shortly after the accident? Too much heat in the aftermath of the tragedy to state the opposition at that time, instead wait until things died down?

Subjects ADSB (All)  ADSB Out  ATC  NTSB  Route 4  Separation (ALL)  Vertical Separation

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WillowRun 6-3
January 28, 2026, 03:09:00 GMT
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Post: 12028338
"The NTSB determines that the probable cause of this accident was the FAA's placement of a helicopter route in close proximity to a runway approach path."

The PC statement should be read in its entirety, and at the conscious risk of ripe cliche, context matters. The Board did not assign the probable cause to the intersecting flight routes as such. For one thing, Chair Homendy repeatedly since the early days of the Board investigation has hammered upon the fact that the vertical separation was as little as 75 feet without any procedural separation (such as the helos holding at Haines Point). And also since the start of the investigation, time and again the complexity of the DCA airspace, and the (in my strident opinion) very messed up operation of DCA with regard to - as ATC staff testified - just "making it work", have been emphasized. Plus the refusal of FAA ATO to act upon the input from the helicopter working group several years ago, plus FAA's declining to note "hot spots" on charts. And the staffing issues, and lack of fidelity to SMS on the part of FAA and to some extent the Army as well. And there were, quite obviously, many findings of fact which are necessarily part of the context for reading . . . and understanding, the PC determination.

A person need not be an aeronautical engineer, airspace architect, or civilian or military aviator to understand from the get-go that intersecting flight paths might be found across the NAS. I'll stand to be corrected but I do not think - having watched the entirety of the hearing today - that the criticism of the Probable Cause finding is a valid, fair or accurate assessment of the Board's work in this investigation.
WillowRun 6-3

Subjects ATC  DCA  FAA  Findings  Helicopter Working Group  Hot Spots  NTSB  NTSB Chair Jennifer Homendy  Probable Cause  Separation (ALL)  Vertical Separation

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artee
January 28, 2026, 03:16:00 GMT
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Post: 12028339
Originally Posted by WillowRun 6-3
"The NTSB determines that the probable cause of this accident was the FAA's placement of a helicopter route in close proximity to a runway approach path."

The PC statement should be read in its entirety, and at the conscious risk of ripe cliche, context matters. The Board did not assign the probable cause to the intersecting flight routes as such. For one thing, Chair Homendy repeatedly since the early days of the Board investigation has hammered upon the fact that the vertical separation was as little as 75 feet without any procedural separation (such as the helos holding at Haines Point). And also since the start of the investigation, time and again the complexity of the DCA airspace, and the (in my strident opinion) very messed up operation of DCA with regard to - as ATC staff testified - just "making it work", have been emphasized. Plus the refusal of FAA ATO to act upon the input from the helicopter working group several years ago, plus FAA's declining to note "hot spots" on charts. And the staffing issues, and lack of fidelity to SMS on the part of FAA and to some extent the Army as well. And there were, quite obviously, many findings of fact which are necessarily part of the context for reading . . . and understanding, the PC determination.

A person need not be an aeronautical engineer, airspace architect, or civilian or military aviator to understand from the get-go that intersecting flight paths might be found across the NAS. I'll stand to be corrected but I do not think - having watched the entirety of the hearing today - that the criticism of the Probable Cause finding is a valid, fair or accurate assessment of the Board's work in this investigation.
WillowRun 6-3
I find it interesting that the actions of the crew of PSA5342 were not included as Probable Cause. How do you think this will affect the lawsuit against them?

Subjects ATC  DCA  FAA  Findings  Helicopter Working Group  Hot Spots  NTSB  NTSB Chair Jennifer Homendy  Probable Cause  Separation (ALL)  Vertical Separation

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