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| YRP
January 31, 2025, 14:14:00 GMT permalink Post: 11818242 |
It's often that way in engineering too. The most valuable engineer in a company is the one that says, "No, don't do it", saving the company billions in not pursuing a dumb idea. Yet there's plenty of companies that do adopt dumb ideas and lose billions in the process. A "can do" culture is a very human thing it seems...
Speaking up like that is often a way to shorten a career at that company\x85 Subjects: None 6 recorded likes for this post.Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
| YRP
February 01, 2025, 14:06:00 GMT permalink Post: 11819045 |
They're audible on the ATC radio transcript ergo of course they are equipped with (and are using) standard VHF radios to communicate with civ ATC and are audible to other aircraft. Unless you think someone's spliced different radio channels together to make a youtube video. Which is, you know, a reach.
That\x92s why using their recordings leads to comments on pprune that the controller was cut off or didn\x92t say something or the aircraft didn\x92t acknowledge. It can be just the scanner not picking it up, because it focuses on one transmission at a time. That\x92s not to comment on whether they had VHF or not. Subjects
ATC
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| YRP
February 01, 2025, 14:26:00 GMT permalink Post: 11819059 |
Agree. Redesigning the Helicopter route or procedure now seems essential.
- but equally describing a fast developing potential collision situation in terms referencing local bridges (was the pilot local ?) is (at least with hindsight) inadequate and something 'far more alarming' could have been said in time. I have only once flown into the Washington area, and it was more than a decade ago in a light single. I seem to recall DCA required special training even for airline pilots. Is that not the case now or not for helicopter pilots? I thought it was a case where you need to be familiar to use those routes. Subjects
DCA
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| YRP
February 01, 2025, 14:37:00 GMT permalink Post: 11819062 |
Talk of it being difficult to pick out aircraft nav lights is a red herring. The heli was, initially, several hundred feet below the CRJ and should have been able to easily see the lights against the night sky.
Blaming the airspace design is also a non starter. Are we really going to say that just because the airspace is poorly designed then I'm just going to fly in to that regional jet over there? First rule of airmanship anyone? Keep a good lookout. Seems like the helicopter crew failed to do so having been given their requested visual separation. Should have had eyes on stalks. No the airspace does not take the blame. Apparently the hello pilots missed the lookout. And the controller could have been clearer, instead of \x93still in sight?\x94 perhaps \x93the RJ is now 1/2 mile 10 o\x92clock, confirm you have him?\x94. (not criticizing him, guessing that he saw them closer than expected, was concerned, and made a very quick call) But the airspace & procedure seems to not tolerate mistakes. There ought to be some safety margin. While not the primary fault, it could be improved. Subjects
ATC
CRJ
Separation (ALL)
Visual Separation
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| YRP
February 01, 2025, 14:45:00 GMT permalink Post: 11819065 |
Which could indicate that the controller was simultaneously transmitting on two frequencies (VHF+UHF) and the frequencies were not cross-coupled, resulting in the traffic on VHF not being able to hear the traffic on UHF, and vice-versa.
Cross-coupling, whereby aircraft transmissions are re-broadcast on the other frequency being used is a mandatory requirement at civil ATC units in UK. This being done to facilitate situational awareness of other traffic by all crews. It\x92s pretty common in Canada, both at Tower and enroute IFR sectors. It\x92s not just for situational awareness, also to prevent overlapping transmissions from aircraft on the two frequencies. So you don\x92t have to try to listen to both as the controller. Even without that the controllers here almost always transmit on all their frequencies rather than just the one the aircraft is on. Subjects
ATC
IFR
Situational Awareness
TCAS (All)
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| YRP
February 01, 2025, 14:56:00 GMT permalink Post: 11819074 |
I guess - as the culprit here - I should clarify that I was wrong; both the VASAviation youtube video and the LiveATC recordings were two different radio channels spliced together, the helo was transmitting on a separate frequency.
The tower was transmitting on both frequencies - I believe - simultaneously. So the CRJ would have heard only the tower's transmissions to the helo ('visual separation approved' x 2) and not the helo's transmissions. It is not always understood on pprune (and again not you, mostly casual posters) that liveatc.net is just hobbyist / enthusiast stuff. It\x92s not reliable. The antenna placement is often poor, so some transmission sounds bad. Same with using ads-b data from various sources and plotting tracks. Sometimes it is meaningful and sometimes the position is way too undersampled. And don\x92t get me started on taking derivatives / differences on noisy undersampled signals to get things like wow look at that vertical speed here. Subjects
CRJ
Separation (ALL)
Visual Separation
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| YRP
February 02, 2025, 01:59:00 GMT permalink Post: 11819443 |
A red collision alert was flashing at this point on the controllers screen, the instruction should\x92ve been for the CRJ to go around, not wasting time on the helicopter pilots.
Secondly, why shouldn\x92t we criticise the controller? Imho his actions need to be criticised. Not the individual but the environment, procedures and training he operated in. The mission of ATC is to prevent exactly this from happening and they failed in their mission. It would happen all the time with visual separation. It\x92s nothing like the RA must-follow-without-question alert. Issuing a go around would often be the exact wrong thing to do. In this case the controller was aware they were close. The accepted procedures look like quite likely the culprit here. They seem to allow a single mistake (misidentifying visual traffic) to become catastrophic. The controller\x85 he\x92s required to use the accepted procedures. If the procedure after safety analysis is to allow helicopters to visually separate from jets, he can\x92t just say not on his shift. He can double check of course, and imho that\x92s what his \x93still got \x91em in sight\x94 call was about, since it clearly concerned him. Anyway my point about not criticizing him was just that my post was not intended that way. I don\x92t have access to listen to the full conversation. If you do, then go ahead. And certainly the environment/procedures/etc are all in question here. Subjects
ATC
CRJ
Separation (ALL)
Visual Separation
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| YRP
February 02, 2025, 02:12:00 GMT permalink Post: 11819450 |
Even so it would be pretty far fetched to say that the firing could now have much effect. 1981 is closer to the first flight of a jet airliner than to today. The firing was stupid etc for sure. Just it has been so long that any shortages now have more to do with policy since then. Subjects: None 1 recorded likes for this post.Reply to this quoting this original post. You need to be logged in. Not available on closed threads. |
| YRP
February 02, 2025, 02:19:00 GMT permalink Post: 11819453 |
Also that plot might include times when helo pilots get other routing due to no DCA traffic. Speculating, but some of those points are pretty close to the airport. Last edited by YRP; 2nd February 2025 at 02:34 . Subjects
DCA
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| YRP
February 03, 2025, 03:07:00 GMT permalink Post: 11820246 |
And in fact he did speak up, asked the helo to confirm in sight. Obviously he saw it was close and wanted to check. Unfortunately he didn\x92t quite say enough. If he\x92d said \x93traffic is 1/2 mile\x94 and the helo was looking at something 2 miles away, they might have twigged to it. Maybe. Subjects
ATC
Radar
Separation (ALL)
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| YRP
February 03, 2025, 03:18:00 GMT permalink Post: 11820250 |
Good post: just because you found some data doesn\x92t mean you understand it. 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. |
| YRP
February 03, 2025, 03:25:00 GMT permalink Post: 11820251 |
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.
Instructing a climb could be useless or dangerous. Instructing no climb, same thing. Engineering safety systems is not simple. You adjust one case, it can worsen another case. Subjects
TCAS (All)
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| YRP
February 03, 2025, 03:31:00 GMT permalink Post: 11820252 |
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. |
| YRP
February 03, 2025, 14:45:00 GMT permalink Post: 11820598 |
"do you have the CRJ in sight" .."pass behind the CRJ" shows indeed he's uncertain of their awareness and wants them on a different heading. But the communication is completely inadequate to resolve the concern in the 15 sec time window left to intersection. It brings zero locational information of either the CRJ or the heading change they need to execute. The best possible outcome was clear to be a very near miss. With according to radar PAT at 200ft, CRJ descending from 500 at 600ft/min, and a 100ft radar resolution, there is zero margin here. So if you don't command a snap heading change at zero projected margin, at what point do you..?
But the controller doesn\x92t know they have the wrong plane. Guess: he\x92s just checking they didn\x92t think they\x92d passed it already. Either way, the controller does not have enough information to use a heading \x97 neither to know one is needed nor what it should be . The radar & display is just not as accurate as a Mark I eyeball in one cockpit seeing the other plane out the window. When would he? \x93Tower, PAT25 has lost that traffic\x94. Until then a vector might bring them *into* a collision. Subjects
ATC
CRJ
Close Calls
PAT25
Pass Behind
Pass Behind (All)
Radar
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| YRP
February 03, 2025, 22:45:00 GMT permalink Post: 11820974 |
They'd already said "Tower, we had an RA. Brickyard 4514 is going around" and that was acknowledged. They were then switched to Potomac who confirmed radar contact and asked reason for go around again. I would hope Potomac had seen/heard the "CA". But then after this everyone just carries on as if this is all perfectly normal until we all know what happened the very next day.
He\x92s asking the reason to find out what the a/c wants: sequence for another approach, divert due weather, hold to work out a technical fault. Tower could have passed it on the hotline but it is probably normally more efficient to just have the a/c say. Working about the safety implication of why the RA and what it says about the procedure is not something for the radio. Subjects
ATC
Radar
Republic Airways Flight 4514 Go-around
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| YRP
February 04, 2025, 04:17:00 GMT permalink Post: 11821110 |
I have never flown in the United States so am not sure, but if this was Australia the controller couldn\x92t give the helicopter a vector while it is below the minimum vectoring altitude anyway. I would be surprised if the controller in DC was able to legally issue a heading instruction to the Blackhawk while it is at or below 200ft at night. Can one of the American readers correct me if I am wrong?
Thanks Subjects
ATC
Blackhawk (H-60)
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| YRP
February 07, 2025, 22:36:00 GMT permalink Post: 11823982 |
The deactivation of the PAT25's ADS-B system meant that it was not broadcasting its position, making it invisible to systems that rely on ADS-B data for situational awareness, including those on AA534. There would be no signal from PAT25 to trigger TCAS alerts to pilots of AA5342. NTSB also said it was 'likely' PAT25 crew were wearing night-vision goggles, which have greatly reduced field of view, as little as 40 degrees
Quite extraordinary for a supposed 'recertification' flight. The recertification flight might specifically need to be at night. It might even specifically require NVG. I also wonder if both pilots would be on NVG or just one of the two. Last edited by YRP; 7th February 2025 at 22:49 . Reason: Edited to sound 10% less grumpy Subjects
AA5342
ADSB (All)
NTSB
Night Vision Goggles (NVG)
PAT25
Situational Awareness
TCAS (All)
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| YRP
February 09, 2025, 20:32:00 GMT permalink Post: 11825106 |
Just to put the things back into perspective : whether the controller had a radar display in front of him or not ,, whether there should have been a separate controller in the Heli frequency ,both would not have changed anything in this case since he delegated separation to the helicopter , The visual identification by the helicopter was confirmed ( twice) , instruction to pass behind was confirmed = controller no longer responsible , standard procedure in DC since the guys worked there , and he had a lot of other traffic to attend to.
To discuss what he could or should have done is just playing " Captain hindsight " The procedure was wrong , the safety case botched , and as I understand, the " book " allowing all this was followed by both the controller and the helicopter pilot . Let's discuss the procedures and visual separation delegation at night in busy airports instead on focusing on what the controller should have done , implying indirectly some form of responsibility in this accident.. A second controller -might- have had more time to observe the conflict. They -might- have twigged and second guessed the helo's separation. But they very well might not have. The spacing might have been close enough to the every day occurances that the controller might not have been able to tell. Having the helicopters on a separate frequency from the fixed wing would certainly not have helped anyone's situational awareness. Subjects
ATC
Pass Behind
Pass Behind (All)
Radar
Separation (ALL)
Situational Awareness
Visual Separation
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| YRP
February 13, 2025, 01:33:00 GMT permalink Post: 11827083 |
On the flying end, there is quite a rigid procedure to follow if a TCAS RA goes off. From posts since I see, that there seems to be one for for STCA triggers too. It seems to me that the gravity of the situation is brought faster to a pilot's attention if the Conflict warning is announced on the RT.
That is just one factor in this sad affair of course. Both TCAS and STCA are last ditch saviours but only if full attention can be paid to them. TCAS RA says that a collision is imminent (within the accuracy of the system, ie it probably means the system can\x92t prove the planes won\x92t hit). Conflict alert is to notify the controller well in advance \x97 maybe a few minutes for en-route. It isn\x92t a loss of separation, it is so they can avoid a loss of separation (3 or 5 miles for radar). Subjects
ATC
Radar
Separation (ALL)
TCAS (All)
TCAS RA
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| YRP
August 01, 2025, 15:56:00 GMT permalink Post: 11931914 |
There's a reason for the normal 500' or 1000' separation between traffic, eg enroute cruising altitudes. Someone once worked out the tolerances and margins. Subjects
ATC
Separation (ALL)
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