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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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DIBO
February 14, 2025, 23:17:00 GMT
permalink Post: 11828288

Quote:

Originally Posted by DIBO

Well, not duplex, but the existing simplex with 'stepping over' protection

Quote:

Originally Posted by MJA Chaser

Or Tx inhibit.

that seems indeed to be the more professional terminology

And before people start jumping all over this 'feature', yes, yes, indeed an extra 'button' needs to be provided on the radio, to knowingly override the 'Tx Inhibit' feature in case of stuck mic., etc.

Subjects: None

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DIBO
February 15, 2025, 00:52:00 GMT
permalink Post: 11828325

Quote:

Originally Posted by MechEngr

Barometric altitude is the only reading that all participants can share. Trying to avoid terrain? Radalt makes sense. Trying to comply with a corridor, barometric altitude. If there is a problem that the radalt is way too low for the barometric, that should be a call to the ATC to find out what the reading is at the airport.

but for this accident, this was all close to irrelevant, as QNH was very close to std.pressure (18ft. diff), Potomac AGL was almost MSL (3ft diff), even airfield/TDZ elevation is only 14ft / 13ft. So baro alt., encoding & radalt all should have been very close. Equipment rounding was even larger (or less small), with the UH60's mode C apparently even reporting rounded to the nearest 100ft (and TWR's BRITE displaying in 'hundreds' only).

Subjects ATC QNH

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DIBO
February 15, 2025, 00:56:00 GMT
permalink Post: 11828328

Quote:

Originally Posted by deltafox44

They stated the crew was likely wearing NVG, this would explain that

and I expect a lot of attention will go to the NVG aspect, as per NTSB brief, the qualification flight was both 'annual' and 'NVG'....

Subjects NTSB Night Vision Goggles (NVG)

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DIBO
February 15, 2025, 02:20:00 GMT
permalink Post: 11828339

Quote:

Originally Posted by airman1900

It would seem to me that "OVER POTOMAC RIVER" and "VIA EAST BANK OF POTOMAC RIVER" would indicate some sort of "boundary."

I think that 'lateral boundary' was implied, as this has also been the focus of some discussions on the internet.
Vertical and routing wise, the description is pretty detailed.

Personally I think these discussions on the lateral width, or the exact position of the route isn't really relevant. Abeam KDCA for example, I expect not exactly hugging the river bank, but remaining well within the eastern half of the river, wouldn't cause any 'pilot deviation'.

Subjects KDCA

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DIBO
February 19, 2025, 23:29:00 GMT
permalink Post: 11831848

Quote:

Originally Posted by deltafox44

Did you take QNH into account ? Ads-B gives pressure altitude

was my initial reaction too, but check the Y-axis description

Subjects QNH

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DIBO
February 27, 2025, 21:56:00 GMT
permalink Post: 11837401

Quote:

Originally Posted by Lonewolf_50

Hold at Hains Point being a common spacing technique in the past, per the discussion in the video with the CW3, makes me wonder why that expedient wasn't resorted to in this case for spacing.

and in addition to this official " non-compulsory holding/reporting point ", it seems they also commonly used " hold at the golf balls ", which is at similar distance from the rwy 15-33 extended centerline, but then on the south side. And only known to the locals and not as a landmark on the map (for obvious (??) reasons)

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....

Subjects Separation (ALL) Visual Separation

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DIBO
August 01, 2025, 22:40:00 GMT
permalink Post: 11932083

Quote:

Originally Posted by Lonewolf_50

As to your point on the cause of the accident, yes, they were not aware of the traffic coming into 33 (for reasons beaten to death already).

What do you mean by " they were not aware of the traffic coming into 33 "? They were specifically informed about the incoming traffic circling into 33.
And they acknowledged it, although in a very short reply (understandable to keep R/T's as short as possible).

But replying with " traffic circling 33 in sight " just might have improved their own SA, helping to build the mental picture that mentioned traffic was going to move slightly to their left and was at some point going to cross their route from left to right. And if they didn't have that mental picture of what "circling 33" meant for their routing, then a lot was wrong long before the impact.

Edit: UH60 CVR transcript of the same (notice the difference in transcript 'circling' <-> 'for')

and yes of course, we all know, beaten to death, etc. that they 'locked' onto the wrong traffic for their visual separation in this very challenging and complex visual situation (not to mention at night with NVG's !!!).

And what strikes me over and over again, is this mutual 'pavlovian' "request visual separation"-"approved" thing, as if proclaiming these words, absolves all involved from any rules/restriction that might hinder the smooth flow of things (which it does - kind of).
Even at the last chance of averting disaster by the controller (by clearly indicating the target), the pavlovian reaction was there again (totally meaningless as it was already requested and approved 96 second earlier)...

... even while not catching the drift of the controller's last R/T (but hey, we said the magic words, so lets keep on moving)

Last edited by DIBO; 2nd August 2025 at 22:03 . Reason: add extract from UH60 CVR transcript (not available/included in NTSB debrief animation)

Subjects ATC Night Vision Goggles (NVG) Separation (ALL) Situational Awareness Visual Separation

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DIBO
August 08, 2025, 00:17:00 GMT
permalink Post: 11934969

Quote:

Originally Posted by Sailvi767

The TCAS display according to the video in the investigation docket did show the traffic all the way to impact.

TCAS gave a TA just prior to that, why should TCAS have lost track?
That's why I don't understand all the fuzz about ADS-B in the UH60. TCAS in the CRJ worked as designed, including RA inhibit down low.

Quote:

It was the last chance to avert this accident.

the CRJ crew getting a visual on the UH60 some seconds earlier could have saved them as well, one of many items on the 'could have saved them' list.

I've wondered a couple of times, what if.... the CRJ crew had failed to spot the UH60 all together. Now a left-banking evasive manoeuver was started, and only the left wing was substantially shredded by the rotor.
If they would has kept wings level, maybe both wings would have narrowly escaped major damage, only MLG and belly at risk of the main rotor.
But it all doesn't matter, really. 'Fate is the hunter' and they got caught.

Subjects ADSB (All) ADSB In CRJ NTSB Docket TCAS (All)

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DIBO
August 11, 2025, 23:34:00 GMT
permalink Post: 11936975

Quote:

Originally Posted by Musician

What was the rationale behind putting the helicopter route that low anyway?

not intending to be cynical, but it makes the helos blend in nicely with the background, sort of out of the way for rwy 01/19 traffic (=95% of total)
I wonder how many pilots on rwy 01/19 really perceived this section of the routing as unsafe (when flown correctly = hugging the shoreline at max 200ft).
A nuisance, undoubtedly. And the whole helicopter traffic surrounding DCA, pretty unsafe, I can understand.
And then we have nighttime...

Quote:

Originally Posted by Musician

Shouldn't aircraft have 1000 ft ground/obstacle clearance in built-up areas, in general? and 500 ft. otherwise?

Quote:

\xa7 91.119 d 1:
A helicopter may be operated at less than the minimums prescribed in paragraph (b) or (c) of this section, provided each person operating the helicopter complies with any routes or altitudes specifically prescribed for helicopters by the FAA

Quote:

Originally Posted by Musician

That route forced helicopters below 200 ft., how can that not be unsafe?

taking the nearby airport out of the equation, I wonder if any of the professional operators on this route 4 section, ever felt that this low-level flying was (unnecessarily) unsafe

Subjects DCA FAA Route 4

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DIBO
August 11, 2025, 23:49:00 GMT
permalink Post: 11936982

Quote:

Originally Posted by Sailvi767

We went around from 400 feet.

with hindsight, this must have been one of your top 10 or even top 3 best pilot-decisions ever?

Subjects: None

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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 Links are to this post in the relevant subject page so that this post can be seen in context. No recorded likes for this post (could be before pprune supported 'likes'). Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
DIBO February 14, 2025, 23:17:00 GMT permalink Post: 11828288	Quote: Originally Posted by DIBO Well, not duplex, but the existing simplex with 'stepping over' protection Quote: Originally Posted by MJA Chaser Or Tx inhibit. that seems indeed to be the more professional terminology And before people start jumping all over this 'feature', yes, yes, indeed an extra 'button' needs to be provided on the radio, to knowingly override the 'Tx Inhibit' feature in case of stuck mic., etc. Subjects: None No recorded likes for this post (could be before pprune supported 'likes'). Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
DIBO February 15, 2025, 00:52:00 GMT permalink Post: 11828325	Quote: Originally Posted by MechEngr Barometric altitude is the only reading that all participants can share. Trying to avoid terrain? Radalt makes sense. Trying to comply with a corridor, barometric altitude. If there is a problem that the radalt is way too low for the barometric, that should be a call to the ATC to find out what the reading is at the airport. but for this accident, this was all close to irrelevant, as QNH was very close to std.pressure (18ft. diff), Potomac AGL was almost MSL (3ft diff), even airfield/TDZ elevation is only 14ft / 13ft. So baro alt., encoding & radalt all should have been very close. Equipment rounding was even larger (or less small), with the UH60's mode C apparently even reporting rounded to the nearest 100ft (and TWR's BRITE displaying in 'hundreds' only). Subjects ATC QNH Links are to this post in the relevant subject page so that this post can be seen in context. 2 recorded likes for this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
DIBO February 15, 2025, 00:56:00 GMT permalink Post: 11828328	Quote: Originally Posted by deltafox44 They stated the crew was likely wearing NVG, this would explain that and I expect a lot of attention will go to the NVG aspect, as per NTSB brief, the qualification flight was both 'annual' and 'NVG'.... Subjects NTSB Night Vision Goggles (NVG) Links are to this post in the relevant subject page so that this post can be seen in context. No recorded likes for this post (could be before pprune supported 'likes'). Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
DIBO February 15, 2025, 02:20:00 GMT permalink Post: 11828339	Quote: Originally Posted by airman1900 It would seem to me that "OVER POTOMAC RIVER" and "VIA EAST BANK OF POTOMAC RIVER" would indicate some sort of "boundary." I think that 'lateral boundary' was implied, as this has also been the focus of some discussions on the internet. Vertical and routing wise, the description is pretty detailed. Personally I think these discussions on the lateral width, or the exact position of the route isn't really relevant. Abeam KDCA for example, I expect not exactly hugging the river bank, but remaining well within the eastern half of the river, wouldn't cause any 'pilot deviation'. Subjects KDCA Links are to this post in the relevant subject page so that this post can be seen in context. No recorded likes for this post (could be before pprune supported 'likes'). Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
DIBO February 19, 2025, 23:29:00 GMT permalink Post: 11831848	Quote: Originally Posted by deltafox44 Did you take QNH into account ? Ads-B gives pressure altitude was my initial reaction too, but check the Y-axis description Subjects QNH Links are to this post in the relevant subject page so that this post can be seen in context. No recorded likes for this post (could be before pprune supported 'likes'). Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
DIBO February 27, 2025, 21:56:00 GMT permalink Post: 11837401	Quote: Originally Posted by Lonewolf_50 Hold at Hains Point being a common spacing technique in the past, per the discussion in the video with the CW3, makes me wonder why that expedient wasn't resorted to in this case for spacing. and in addition to this official " non-compulsory holding/reporting point ", it seems they also commonly used " hold at the golf balls ", which is at similar distance from the rwy 15-33 extended centerline, but then on the south side. And only known to the locals and not as a landmark on the map (for obvious (??) reasons) 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.... Subjects Separation (ALL) Visual Separation Links are to this post in the relevant subject page so that this post can be seen in context. 1 recorded likes for this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
DIBO August 01, 2025, 22:40:00 GMT permalink Post: 11932083	Quote: Originally Posted by Lonewolf_50 As to your point on the cause of the accident, yes, they were not aware of the traffic coming into 33 (for reasons beaten to death already). What do you mean by " they were not aware of the traffic coming into 33 "? They were specifically informed about the incoming traffic circling into 33. And they acknowledged it, although in a very short reply (understandable to keep R/T's as short as possible). But replying with " traffic circling 33 in sight " just might have improved their own SA, helping to build the mental picture that mentioned traffic was going to move slightly to their left and was at some point going to cross their route from left to right. And if they didn't have that mental picture of what "circling 33" meant for their routing, then a lot was wrong long before the impact. Edit: UH60 CVR transcript of the same (notice the difference in transcript 'circling' <-> 'for') and yes of course, we all know, beaten to death, etc. that they 'locked' onto the wrong traffic for their visual separation in this very challenging and complex visual situation (not to mention at night with NVG's !!!). And what strikes me over and over again, is this mutual 'pavlovian' "request visual separation"-"approved" thing, as if proclaiming these words, absolves all involved from any rules/restriction that might hinder the smooth flow of things (which it does - kind of). Even at the last chance of averting disaster by the controller (by clearly indicating the target), the pavlovian reaction was there again (totally meaningless as it was already requested and approved 96 second earlier)... ... even while not catching the drift of the controller's last R/T (but hey, we said the magic words, so lets keep on moving) Last edited by DIBO; 2nd August 2025 at 22:03 . Reason: add extract from UH60 CVR transcript (not available/included in NTSB debrief animation) Subjects ATC Night Vision Goggles (NVG) Separation (ALL) Situational Awareness Visual Separation Links are to this post in the relevant subject page so that this post can be seen in context. 3 recorded likes for this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
DIBO August 08, 2025, 00:17:00 GMT permalink Post: 11934969	Quote: Originally Posted by Sailvi767 The TCAS display according to the video in the investigation docket did show the traffic all the way to impact. TCAS gave a TA just prior to that, why should TCAS have lost track? That's why I don't understand all the fuzz about ADS-B in the UH60. TCAS in the CRJ worked as designed, including RA inhibit down low. Quote: It was the last chance to avert this accident. the CRJ crew getting a visual on the UH60 some seconds earlier could have saved them as well, one of many items on the 'could have saved them' list. I've wondered a couple of times, what if.... the CRJ crew had failed to spot the UH60 all together. Now a left-banking evasive manoeuver was started, and only the left wing was substantially shredded by the rotor. If they would has kept wings level, maybe both wings would have narrowly escaped major damage, only MLG and belly at risk of the main rotor. But it all doesn't matter, really. 'Fate is the hunter' and they got caught. Subjects ADSB (All) ADSB In CRJ NTSB Docket TCAS (All) Links are to this post in the relevant subject page so that this post can be seen in context. No recorded likes for this post (could be before pprune supported 'likes'). Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
DIBO August 11, 2025, 23:34:00 GMT permalink Post: 11936975	Quote: Originally Posted by Musician What was the rationale behind putting the helicopter route that low anyway? not intending to be cynical, but it makes the helos blend in nicely with the background, sort of out of the way for rwy 01/19 traffic (=95% of total) I wonder how many pilots on rwy 01/19 really perceived this section of the routing as unsafe (when flown correctly = hugging the shoreline at max 200ft). A nuisance, undoubtedly. And the whole helicopter traffic surrounding DCA, pretty unsafe, I can understand. And then we have nighttime... Quote: Originally Posted by Musician Shouldn't aircraft have 1000 ft ground/obstacle clearance in built-up areas, in general? and 500 ft. otherwise? Quote: \xa7 91.119 d 1: A helicopter may be operated at less than the minimums prescribed in paragraph (b) or (c) of this section, provided each person operating the helicopter complies with any routes or altitudes specifically prescribed for helicopters by the FAA Quote: Originally Posted by Musician That route forced helicopters below 200 ft., how can that not be unsafe? taking the nearby airport out of the equation, I wonder if any of the professional operators on this route 4 section, ever felt that this low-level flying was (unnecessarily) unsafe Subjects DCA FAA Route 4 Links are to this post in the relevant subject page so that this post can be seen in context. 1 recorded likes for this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
DIBO August 11, 2025, 23:49:00 GMT permalink Post: 11936982	Quote: Originally Posted by Sailvi767 We went around from 400 feet. with hindsight, this must have been one of your top 10 or even top 3 best pilot-decisions ever? Subjects: None No recorded likes for this post (could be before pprune supported 'likes'). Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

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