February 22, 2025, 01:37:00 GMT
permalink Post: 11833388
I can think of one: you apply IFR separation standards (the minimum in the US is 1.5nm/500\x92?), at least for night operations. If two routes come closer to each other than that in either dimension, e.g. DCA RW33 approach and helicopter route 1, then traffic must be actively kept apart.
If two aircraft are converging on the same runway or look like they are going to occupy it simultaneously, then one of them has to give way. Why should it be any different for a small volume of sky?
If two aircraft are converging on the same runway or look like they are going to occupy it simultaneously, then one of them has to give way. Why should it be any different for a small volume of sky?
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February 22, 2025, 07:49:00 GMT
permalink Post: 11833471
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February 22, 2025, 09:48:00 GMT
permalink Post: 11833528
I can think of one: you apply IFR separation standards (the minimum in the US is 1.5nm/500’?), at least for night operations. If two routes come closer to each other than that in either dimension, e.g. DCA RW33 approach and helicopter route 1, then traffic must be actively kept apart.
- Class B : Operations may be conducted under IFR, SVFR, or VFR. All aircraft are subject to ATC clearance. All flights are separated from each other by ATC.
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February 22, 2025, 10:39:00 GMT
permalink Post: 11833564
Which, put another way, means no visual separation, and I think that's the right answer. I would commend the DCA authorities also to a scheme we had in London where regular users of the routes such as PAT are given a number to call before planned movements to see if it was likely to come off. Another trick that I've seen is to add a suffix to the callsign for aircraft on a priority shout (eg. helimed).
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February 22, 2025, 11:12:00 GMT
permalink Post: 11833584
I can think of one: you apply IFR separation standards (the minimum in the US is 1.5nm/500\x92?), at least for night operations. If two routes come closer to each other than that in either dimension, e.g. DCA RW33 approach and helicopter route 1, then traffic must be actively kept apart
However, from a US point of view, this is arguably the solution which was in place on the night. It's just that the means of actively keeping the traffic apart, ie visual separation, failed. I am prepared to accept that FAA-style "visual separation" is slightly more robust than "see and avoid" in that it requires ATC to confirm that the pilot has the specific traffic in sight before relaxing separation minima, but the question for the FAA is whether "slightly more robust" is good enough when airliners are involved, particularly at night given the increased potential for misidentification.
I am not sure the subsequent line of discussion over how Class B requires ATC (not pilots) to separate all traffic is a very productive one. Any separation instruction given by ATC relies upon the pilot executing it, for instance by maintaining the cleared altitude. Here, it relied on the pilot not colliding with the specific traffic he had confirmed visual contact with. So far as the FAA is concerned, that's a sufficient degree of control and differs from the "see and avoid" principle applicable to VFR/VFR in Class C, and VFR/Any in Class D. Again, the question is whether that's appropriate.
That last point gives me an opportunity to make an observation I've been pondering for a while. Many European airport control zones are Class D, where on a strict reading of ICAO, VFR traffic is not required to be separated from IFR. But how many of us know a Class D zone where the controller gives traffic information and lets VFR traffic merge with IFR under see and avoid? In practice, European and especially UK ATC exercise a greater degree of control than is strictly required by the ICAO classification. At least in my experience, US airspace is operated closer to ICAO specifications ("visual separation" nothwithstanding).
Last edited by Easy Street; 22nd February 2025 at 11:31 .
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February 22, 2025, 11:14:00 GMT
permalink Post: 11833589
I'm sure it does, but UK helimeds use the suffix to indicate they are actually on a shout, rather than training or positioning.
That's not called for. PEI 3721 has a respectful and thoughtful response to your post.
I personally don't think there's anything to be gained from going down the ICAO route. The NTSB has it's own charter and that's what dictates what happens in the USA.
I can see several ways the NTSB could take this, first the obvious one. The helicopter assumed responsibility for separation when it was not able to do so, and then found itself on track for collision. That's what I would define as true proximate cause. Then there's a step back from there which says nobody should be allowed to request and receive visual separation responsibilities in Class B airspace. That would be a good result as far as I'm concerned.
And the final step, which I think is more contentious and really hard for the US to accept, is that the culture at the FAA and within the industry is to balance safety and boosterism for the industry, and I think that is a recipe for irreconcilable conflicts. I'm not holding my breath on that one.
I'm surprised that this is your conclusion. I think what I take away from the conversations on the night was that ATC was divesting himself of responsibility, and the helicopter was trying to expedite his sortie, and nothing in the 'system' prevented them from doing that. Removal of visual separation as an option IMHO deals with that hole in the cheese. It seems like you're suggesting that the helicopter might ignore instructions to hold before the tidal basin ?
Caley's Coachman:
My apologies, I tend to regard the conversation here as being reflective of the lounge bar rather than the witness box. You're right, 'recommends' is a better word and I will try to be more pedantic.
I personally don't think there's anything to be gained from going down the ICAO route. The NTSB has it's own charter and that's what dictates what happens in the USA.
I can see several ways the NTSB could take this, first the obvious one. The helicopter assumed responsibility for separation when it was not able to do so, and then found itself on track for collision. That's what I would define as true proximate cause. Then there's a step back from there which says nobody should be allowed to request and receive visual separation responsibilities in Class B airspace. That would be a good result as far as I'm concerned.
And the final step, which I think is more contentious and really hard for the US to accept, is that the culture at the FAA and within the industry is to balance safety and boosterism for the industry, and I think that is a recipe for irreconcilable conflicts. I'm not holding my breath on that one.
Easy Street:
I am not sure the subsequent line of discussion over how Class B requires ATC (not pilots) to separate all traffic is a very productive one. Any separation instruction given by ATC relies upon the pilot executing it, for instance by maintaining the cleared altitude. Here, it relied on the pilot not colliding with the specific traffic he had confirmed visual contact with. So far as the FAA is concerned, that's a sufficient degree of control and differs from the "see and avoid" principle applicable to VFR/VFR in Class C, and VFR/Any in Class D. Again, the question is whether that's appropriate.
Last edited by Wide Mouth Frog; 22nd February 2025 at 11:49 . Reason: Adding response to Easy Street
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ATC
FAA
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NTSB
See and Avoid
Separation (ALL)
Visual Separation
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February 22, 2025, 11:57:00 GMT
permalink Post: 11833610
I'm surprised that this is your conclusion. I think what I take away from the conversations on the night was that ATC was divesting himself of responsibility, and the helicopter was trying to expedite his sortie, and nothing in the 'system' prevented them from doing that. Removal of visual separation as an option IMHO deals with that hole in the cheese.
It seems like you're suggesting that the helicopter might ignore instructions to hold before the tidal basin ?
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February 22, 2025, 12:07:00 GMT
permalink Post: 11833616
Sorry, I may have over-interpreted your response. This is the line that prompted that.
I agree there's room for nuances in the visual separation thing, but opposite direction at night is a bridge too far IMHO.
Any separation instruction given by ATC relies upon the pilot executing it
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February 22, 2025, 17:10:00 GMT
permalink Post: 11833773
I am not sure the subsequent line of discussion over how Class B requires ATC (not pilots) to separate all traffic is a very productive one. Any separation instruction given by ATC relies upon the pilot executing it, for instance by maintaining the cleared altitude. Here, it relied on the pilot not colliding with the specific traffic he had confirmed visual contact with. So far as the FAA is concerned, that's a sufficient degree of control and differs from the "see and avoid" principle applicable to VFR/VFR in Class C, and VFR/Any in Class D. Again, the question is whether that's appropriate.
.
Listening to the NTSB , the only ATC instruction given : to " pass behind " was not received , and therefore not acknowledged by the crew , so we are here 100% in the good old "see and avoid" scenario I would say
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FAA
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Pass Behind
Pass Behind (All)
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February 22, 2025, 18:56:00 GMT
permalink Post: 11833817
From what I understand the delegation of separation used in the US is based on the "see and avoid ", It is basically delegating the positive control (ATC separation instructions ) from the controller to the pilot , who has to acquire the traffic visually and maintain visual contact and maneuvers to avoid it . = traffic info from ATC + See and avoid.
When genuine "see and avoid" applies (Class C VFR/VFR, Class D VFR/Any) the controller does not need to confirm that VFR pilots have visual contact before allowing separation to reduce, because there *are no* separation minima. At least, not according to ICAO.
As I mentioned earlier, European and especially UK ATC tends to apply more stringent separation than ICAO requires. The 'ATC duty of care' argument in the UK results in its Class D being operated in a similar way to US Class B, in my experience.
Last edited by Easy Street; 22nd February 2025 at 19:10 .
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ATC
FAA
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See and Avoid
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February 23, 2025, 11:43:00 GMT
permalink Post: 11834188
When operating in the USA (20+ years ago) I was told, "if ATC ask if you can see XXX traffic, say negative."
If everybody denied visual contact with the other traffic in IFR conditions then ATC will be really pissed, but will have to provide you separation. Isn't that still the case? You can never be completely sure that what you can actually see is the traffic ATC want you to see.
If everybody denied visual contact with the other traffic in IFR conditions then ATC will be really pissed, but will have to provide you separation. Isn't that still the case? You can never be completely sure that what you can actually see is the traffic ATC want you to see.
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IFR
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February 23, 2025, 12:09:00 GMT
permalink Post: 11834211
When operating in the USA (20+ years ago) I was told, "if ATC ask if you can see XXX traffic, say negative."
If everybody denied visual contact with the other traffic in IFR conditions then ATC will be really pissed, but will have to provide you separation. Isn't that still the case? You can never be completely sure that what you can actually see is the traffic ATC want you to see.
If everybody denied visual contact with the other traffic in IFR conditions then ATC will be really pissed, but will have to provide you separation. Isn't that still the case? You can never be completely sure that what you can actually see is the traffic ATC want you to see.
Lufty at SFO
ATC will still have to provide you with separation, yes. But some US airports have too much traffic to operate without pilots accepting visual separation, so you may have to land elsewhere. Hence the discussion upthread about the inseparability of regulation from policy, economics and (ultimately) politics.
Post #10 on that thread...
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February 23, 2025, 13:03:00 GMT
permalink Post: 11834248
At what distance and light conditions should any average (heli) pilot be able to identify specifically a \x93CRJ\x94 ?
That stand alone, or after having been told what other traffic was in range and view. For example another being a biz jet or A320.
And this question for both daytime and at night.
Would that performance improve when ATC would supply them with say \x93at your 11 o\x92clock and 1,500 ft and 150 kt and intent (visual to rwy33)?
And would that performance improve at say 3 o\x92clock?
Amazed that visual separation responsibility ended up in the lap of the \x91least able\x92 party involved that some here describe as being \x91clinically\x92 blind !
On the NTSB - as far as I have understood it, they can study and recommend on anything. They could for example start an SS parallel to this investigation addressing this wider issue.
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ATC
NTSB
Separation (ALL)
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February 23, 2025, 15:21:00 GMT
permalink Post: 11834312
At night, pretty near impossible to distinguish a CRJ from another set of lights in the stream unless you know the landing light configuration of each type. During the day, maybe a couple of miles. Otherwise, it’s all about, “At your 11 o’clock, 3 miles and third in the stream”, then you can identify them, not by type but by “third on final”. The Army crew is just whistling Dixie when they accept visual separation with an CRJ seven miles away at night.
Last edited by galaxy flyer; 23rd February 2025 at 20:28 .
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February 27, 2025, 21:56:00 GMT
permalink Post: 11837401
On thing that was strikingly absent in the interview, was an in-depth discussion on the use (or might I say abuse) of the " request visual separation ". This aspect is crucial in this accident, but I have a hunch that this topic is too sensitive to be commented on by a former colleague....
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February 28, 2025, 00:11:00 GMT
permalink Post: 11837458
At night, pretty near impossible to distinguish a CRJ from another set of lights in the stream unless you know the landing light configuration of each type. During the day, maybe a couple of miles. Otherwise, it’s all about, “At your 11 o’clock, 3 miles and third in the stream”, then you can identify them, not by type but by “third on final”. The Army crew is just whistling Dixie when they accept visual separation with an CRJ seven miles away at night.
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CRJ
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March 01, 2025, 09:36:00 GMT
permalink Post: 11838415
IMO the fact that the helo crew didn't readback/acknowledge "pass behind" is irrelevant. Twice before, they told the LC that they had the CRJ in sight and requested visual sep, which was granted. Surely you don't specifically need to be told to not hit the CRJ after you've reported it in sight?
I think the LC saw what was unfolding and said that because he had concerns that the chopper didn't actually have the CRJ. He was right.
I think the LC saw what was unfolding and said that because he had concerns that the chopper didn't actually have the CRJ. He was right.
PAT25 says (for the second time), “Traffic visual, request visual separation”,
which is not true, evidently they were not visual at all because they crashed into the CRJ.
LC responds, “Visual separation approved, [pass behind the] CRJ,”
which clearance was issued on the false premise that PAT25 was visual. But PAT 25 only hears, “Visual separation approved…[pause]…CRJ,” because they briefly stepped on the LC’s transmission themselves. No read back is forthcoming; the LC should be expecting one but he fails to chase it up, because he’s too busy.
If PAT 25 realised he’s stepped on the middle part of the LC’s transmission to himself (which likely could have included an instruction) then he ought to be professional enough to say, “Stepped on, say again,” etc and make absolutely sure he knows what the clearance may have been. That was standard practice a long time ago, but no longer, it seems.
My original point was that in the Mover/Gonky video (post #1228) it was suggested that it’s perfectly OK to second guess what ATC might have said to you, reply to that, and then if no correction is forthcoming you can comply with your guess. As others have pointed out implicitly, that works if there’s only one error involved, but here there were three: an untrue statement, leading to a wrongly issued clearance, and a missing read back.
System broken.
Last edited by Stagformation; 2nd March 2025 at 23:42 .
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PAT25
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March 05, 2025, 02:07:00 GMT
permalink Post: 11841017
LC says, “PAT25, do you have the CRJ in sight?”
PAT25 says (for the second time), “Traffic visual, request visual separation”,
which is not true, evidently they were not visual at all because they crashed into the CRJ.
LC responds, “Visual separation approved, [pass behind the] CRJ,”
which clearance was issued on the false premise that PAT25 was visual. But PAT 25 only hears, “Visual separation approved…[pause]…CRJ,” because they briefly stepped on the LC’s transmission themselves. No read back is forthcoming; the LC should be expecting one but he fails to chase it up, because he’s too busy.
If PAT 25 realised he’s stepped on the middle part of the LC’s transmission to himself (which likely could have included an instruction) then he ought to be professional enough to say, “Stepped on, say again,” etc and make absolutely sure he knows what the clearance may have been. That was standard practice a long time ago, but no longer, it seems.
My original point was that in the Mover/Gonky video (post #1228) it was suggested that it’s perfectly OK to second guess what ATC might have said to you, reply to that, and then if no correction is forthcoming you can comply with your guess. As others have pointed out implicitly, that works if there’s only one error involved, but here there were three: an untrue statement, leading to a wrongly issued clearance, and a missing read back.
System broken.
PAT25 says (for the second time), “Traffic visual, request visual separation”,
which is not true, evidently they were not visual at all because they crashed into the CRJ.
LC responds, “Visual separation approved, [pass behind the] CRJ,”
which clearance was issued on the false premise that PAT25 was visual. But PAT 25 only hears, “Visual separation approved…[pause]…CRJ,” because they briefly stepped on the LC’s transmission themselves. No read back is forthcoming; the LC should be expecting one but he fails to chase it up, because he’s too busy.
If PAT 25 realised he’s stepped on the middle part of the LC’s transmission to himself (which likely could have included an instruction) then he ought to be professional enough to say, “Stepped on, say again,” etc and make absolutely sure he knows what the clearance may have been. That was standard practice a long time ago, but no longer, it seems.
My original point was that in the Mover/Gonky video (post #1228) it was suggested that it’s perfectly OK to second guess what ATC might have said to you, reply to that, and then if no correction is forthcoming you can comply with your guess. As others have pointed out implicitly, that works if there’s only one error involved, but here there were three: an untrue statement, leading to a wrongly issued clearance, and a missing read back.
System broken.
Good points, especially the first, Keep in mind that no readback was required, and that type of instruction doesn't require a readback and according to the AIM is not even a type that "should" be read back, so the controller wouldn't be surprised if he didn't get one. Agree with Capn Bloggs;even if PAT25 didn't get the particular "pass behind" transmission, visual separation, which came up twice, carries the implicit instruction "Don't hit the other aircraft" ( no sarcasm intended), regardless of the method employed.
Last edited by Commando Cody; 5th March 2025 at 02:45 . Reason: Add reference to another post
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March 05, 2025, 11:58:00 GMT
permalink Post: 11841230
Originally Posted by
Stag
simply confirms the helicopter crew had no idea of the imminent danger they were in.
Now if the controller had said "you look to be tracking very close to the CRJ are you sure you can pass behind?" or similar, then maybe the helo crew would have got excited. A call like that might have even triggered a "holy sh1t" moment about the TCAS "Traffic". But as far as they were concerned, they knew they had the traffic in sight and could do the visual sep thing and even if they had heard "pass behind" they would have said/thought "well, obviously". Except they had the wrong aircraft. ATC had an idea they had the wrong aircraft but didn't get the message across.
As for the reference, same thing. The helo crew could have read-back "pass behind" but it wouldn't have achieved anything.
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ATC
CRJ
Pass Behind
Pass Behind (All)
Separation (ALL)
TCAS (All)
Traffic in Sight
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March 05, 2025, 19:00:00 GMT
permalink Post: 11841477
In this scenario, there is zero information in the call to "pass behind" that indicates any imminent danger. All it does is further legitimise the previous two approvals for visual separation.
Now if the controller had said "you look to be tracking very close to the CRJ are you sure you can pass behind?" or similar, then maybe the helo crew would have got excited. A call like that might have even triggered a "holy sh1t" moment about the TCAS "Traffic". But as far as they were concerned, they knew they had the traffic in sight and could do the visual sep thing and even if they had heard "pass behind" they would have said/thought "well, obviously". Except they had the wrong aircraft. ATC had an idea they had the wrong aircraft but didn't get the message across.
As for the reference, same thing. The helo crew could have read-back "pass behind" but it wouldn't have achieved anything.
Now if the controller had said "you look to be tracking very close to the CRJ are you sure you can pass behind?" or similar, then maybe the helo crew would have got excited. A call like that might have even triggered a "holy sh1t" moment about the TCAS "Traffic". But as far as they were concerned, they knew they had the traffic in sight and could do the visual sep thing and even if they had heard "pass behind" they would have said/thought "well, obviously". Except they had the wrong aircraft. ATC had an idea they had the wrong aircraft but didn't get the message across.
As for the reference, same thing. The helo crew could have read-back "pass behind" but it wouldn't have achieved anything.
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ATC
CRJ
Pass Behind
Pass Behind (All)
Separation (ALL)
TCAS (All)
Traffic in Sight
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