Posts about: "Visual Separation" [Posts: 250 Page: 10 of 13]¶

Having quite a few questions:

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.

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.

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....

I am just a lowly multi/commercial pilot who flies mostly for recreation. Since the advent of ADS-B, we have had much more precise information on what traffic is around us, what type they are, and exactly what they are doing heading/altitude/speed-wise. With that data, I've noted that even when I know EXACTLY where to look for a specific type of traffic during daylight hours, for example over an easy to identify landmark, I generally need to be within 3 miles or so to be able to reliably spot it amongst ground clutter and terrain. I'd need to be considerably closer in order to identify a specific type. At night you might be able spot some traffic from further away, but as you note it s even more difficult to determine the type. In the past you might be able to know you were looking for a CRJ and therefore eliminate the Cessna Skyhawk with a single PAR36 incandescent bulb. But these days I have a friend with a Skyhawk that has a LED in the nose, wig-wag LEDs in the wingtips, and Airbus style double flash strobes, and that thing looks like a much larger aircraft at night now. Or maybe like a UFO.

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.

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.

Yes, the RT added no more traffic information than before and completely failed to get the imminent danger across to the IP on the helicopter. However someone may have got a hint because there was a subsequent conversation between crew members about whether they should move further east. But we don’t know yet if that conversation was actually about traffic deconfliction. It could just be about accurate tracking of the left bank of the Potomac or something else entirely.

Even a non-pilot, non-engineer (and worse, an SLF/attorney) is able to understand the difficulties created by relying on visual separation at night, and more specifically, relying on it given the facts of runways in use on the night of the accident (i.e., that the clearance to the helicopter did not make it clear that the traffic advisory was meant to refer to an aircraft "circling" for approach and landing to Runway 33).

Reading this thread since the night of the accident, many have noted the "wrong-thinking" (for lack of a better term) underpinning the way traffic was managed by FAA and ATC.

I'm not enthused about the litigation that almost certainly will be intense once it commences. But reading the thread I've started to wonder.....

What would a chronological reconstruction of each incremental decision by FAA about the operation of DCA look like, a chronology that would (of course) include each Congressional enactment requiring or allowing further intensity of operations? The airport did not go from a nominal operational environment, with typically safe procedures and airspace usage rules very similar to or the same as any other major urban airport in the country, to the situation which obtained on January 29, overnight - or so it would seem.

(Yes, reconstructing the facts to build such a chronology would involve quite a lot of discovery activities in the presumably forthcoming lawsuits, but I'm not veering off into any further comment about why that would matter or which party or parties it would help or hurt..... other than to say, very often, cases are won and lost in discovery.)

Some years ago, on a trip to Capitol Hill hoping to find gainful employment on a Congressional staff somewhere, on the return flight from what then was Washington National, the aircraft's cockpit door was open as the boarding process was being completed (it was 1987). I recall being seated close enough to the flight deck - leaning a little into the aisle (a Midway Airlines DC-9 iirc) - to be able to see the pilot in the LHS and part of the D.C. skyline through the cockpit's front windows. Maybe that is why my mind somehow can't quite comprehend the recollections from kidhood of reading about the midair collision over New York City which is featured prominently in the book Collision Course , together with the events of the night of January 29.

Added: Wall Street Journal, March 6: "Air-Traffic Staff Rules Tightened After Crash." Also reports previous "close call" incident. Highly recommended reading (and I didn't see anything to contradict the above post, WR 6-3).

It may seem that way but not the case. Any of the flight tracker programs show regular helicopter activity inside the Beltway with plenty of medical helo ops plus LEO ops (FFX, PG, DC, MSP, USCG). Even a few news helos. What does seem to have changed is PAT ops inside the Beltway, at least temporarily. Training flights have shifted outside the Beltway to a variety of locations, including Route 9. Two PAT flights today circumnavigated the Beltway.

Not sure what you mean by this comment. CW3 Roth interview explained the training requirement for Route 1/4 ops. Question is whether these training flights can be conducted safely. I think they can as long as ATC doesn\x92t delegate their primary responsibility for Class B separation. It is politically untenable to resume Route 1/4 PAT training flights at present. I suspect 12th AB and DCA ATC are reviewing their previous policy that VFR visual separation is safe along these routes.

Hiya WR 3-6 , thanks for your reply. A busy day today so I'll give this more time tomorrow if I may! But interesting points again - and I'm a bit clearer too on this "discretionary" aspect - I think!!!!

Hi missy , sorry, what I was trying to say was, and this is from further back in the Thread, it is my understanding that often there is 1 controller handling main arrivals & departures with another controller handling local traffic on the heli routes etc. As is often the case, at quiet times, one position closes and so the 1 controller is now controlling both. That is very common practice both at airports and en-route. The others are, indeed, there in support but things happen (eg the Supervisor is asked a question or gets a phone call - similar with the Assistant.). Not saying that happened here but it illustrates the support aspect of those roles and what can happen.

Now, one could say, "Well, there was a fairly steady flow of (maybe) 10 aircraft landing/taking off. So, 1 extra helicopter is not much more to add in!". True ...... but ...... an example. A mainline train arrives at a major London Station and, at once, all the doors open and several 1000 people all get off together and start heading up the stairs to the ticket barriers. The flow of traffic is heavy but quite ordered as the flow is all in one direction and so, while traffic density up the stairs maybe slows it down a bit, the flow is nicely ordered. Picture now, H 'n' H , being in a rush and so being one of the first off the train arriving at the ticket barrier only to realise - Durrrr - he's left his case back on the train. Being not-too-bright, I decide the quickest way to go back is down the same stairs I came up, and hence back to the train. Of course there's only 1 of me going down and several 1000 coming up. But to an onlooker gazing down, the effect of my single trip back against the several 1000 heading up has had a significant effect. TBH, H 'n' H is causing a fair degree of chaos as he pushes past everyone fighting his way back down the stairs against the flow. A few choice comments are being made by his fellow pax! What we have is a disproportionate effect caused by 1 vs 1000's.

So, while I'm no expert in how the brain works, usually the ATCO is dealing with a steady flow S - N and is sequencing things in their mind to smoothly land and depart traffic, slotting people in and out of the queue to achieve an orderly, safe, flow. All of a sudden, their "mental flow" now has something working in the other direction which all needs a bit more thought to ensure that everything remains safe. OK, 1 helo is not much, but it requires a disproportionate amount of extra "computing" compared to, say, adding another 1 aircraft into the main flow, to ensure safe separation. Was that why the "Own visual separation" offer was taken up? Now, rather than managing the contraflow, the ATCO only has to "monitor" the singleton swimming against the tide - which they were to a degree. Just a thought.

Spot on! I'm not sure how long such tapes are kept? Usually it is a defined period after which the tape is recycled into the "system". Of course, looking further back, and in a perfect world, you could assess ATC SOPs against the buildup in traffic over the years and see how that's affected things over time. Was it the case of "a death by a 1000 cuts" which WR 3-6 cited? Sadly, I suspect we'd need a crystal ball to study that. But retired Controllers could give a fairly good insight.

I mean the Airport Operator running the airfield. So, in the UK, that could be a company who then employ the Twr controllers to run that side just as they employ or contract Baggage Handlers, Cleaners, etc, etc. The UK ANSP (NATS) generally pick up everything above 4000 ft tho the actual hand-offs vary tactically and there can be local variations to suit specific airspace. So, for example, from memory, the Channel Islands work up to a higher level before en-route takes over. Below that, its up to the Airport Operator to staff their operation and make sure it's all safe and sound.

Anyway, better dash as already late........! Before yet more chaos is caused by H 'n' H !!!!!!

Hmmm. I'm going to extend your Chicago traffic analogy. Imagine that traffic regulations permitted things known to degrade safety, but which at least some road users wanted: heavily tinted glass, freedom to use handheld cellphones while driving, higher levels of blood alcohol etc. Would the resulting accidents be down to negligence of drivers for being insufficiently skilled to avoid causing accidents under the prevailing regulatory conditions, or down to negligence of the regulators for permitting obviously less safe things to please certain parts of the road user community?

Of course in this case the thing known to degrade safety is "see and avoid", the regulator is the FAA, and the relevant parts of the user community appear to be "near as damn all of it". Focusing on the Army pilots' failure to achieve it would be a neat distraction from the much more difficult question (for everyone) of whether it is an appropriately safe means of separating from airline traffic. The nice NTSB diagram of Route 4 and the 75 feet spacing dodges the issue that neither the controller nor the Army pilots assumed that procedural separation existed; visual separation was being applied.

The permanent closure of Route 4 could be seen as acceptance that this was an unsafe basis on which to permit operations. However it still misses the point. The route was capable of being operated safely, for instance by holding helicopter traffic or avoiding use of runway 33 when needed to prevent conflictions, but that would have been tacitly to accept that visual separation was unsafe. Closing the route also only fixes the issue on one runway at one airport. Where next?

Not from a retired DC controller but from a current one , quote taken from another ATC forum :
The bold additions are mine . Just that we are absolutely clear , those are opinions , not facts .

That is not the one I mean . The radar track video (a screen shot is on post 848 but the video is clearer) show a slight right turn less than a minute or so before the collision . Even if they were just correcting the course to be exactly on track, it makes no sense to turn towards the right to avoid a aircraft on finals on either 01 or worse 33. That is my point . What did they see,? or did they just requested visual separation as a standard call to proceed without restrictions and :" in sight" while still looking for the traffic as some US controllers discussed in another forum .

Disappointed to hear that. Searching for or expecting genuine emotion in the political theater of a congressional hearing is like searching for virtue in a brothel.

I also watched the hearing and learned little new from the parade of platitudes and witness obfuscation. I thought far too much time was spent on ADS-B (an acronym which Maria Cantwell is incapable of uttering correctly). No discussion on use of visual separation. There were a few new points:

1. Cause of spurious DCA TCAS alerts. ME links in related thread.
2. When NTSB examined other Blackhawks of 12th AB fleet, found significant number which did not transmit ADS-B even when ADS-B switched on. One helo (accident helo?) was found to have not transmitted ADS-B for past 700+ days.

Unfortunately, and I hate to say this, I have reached a conclusion beyond those reached by other posters to this forum, to wit:
The US Army, in order to meet its mission requirements, really does not want civilian pilots (commercial or otherwise) to know where its helicopters are. My evidence for this is: The eagerness of the US Army pilots to assume responsibility for seeing and avoiding commercial aircraft; The DCA tower procedures that do not allow civilian fixed wing pilots to hear the conversations between the tower and the helicopters; The Army practice of turning off ADS-B out while on missions and training flights that follow mission profiles (as explained by the USA general in the hearing); The Army's refusal to produce the memo regarding its use of ADS-B to Senator Cruz.
Should the policies adopted by the US Army be regarded as the fundamental cause of this accident?

VHOED191006 , and others interested.

Dumbo Question 3

As you are no doubt aware TWR Visual Separation is a very powerful tool / method in the eyes of the controller or in the eyes of a delegated pilot. (Literally and metaphorically speaking, i.e pun intended.)

It is the very basis of ATC Aerodrome Control. Sophisticated use requires experience and excellent situational awareness.

I just wonder how many (if any) of the “reported” near collisions in the NTSB Preliminary report going back 4 and 14 years respectfully included perfectly safe visual separation?

The small elephant in the room.

The 'elephant in the room' to me is that there seems to be no actual definition of 'perfectly safe visual separation'. One pilot's reckless disregard might be another's overly cautious .

Is there such a thing? I flew gliders, there have been mid-airs (some fatal) despite only flying in daylight & decent vis, and despite the development of Flarm.

ATCDumbo
I'm all ears, excellent point. This focus on ADSB-OUT, and ADSB-IN is really a furphy in terms of this investigation to determine the facts, the whole facts and nothing but the facts.

If 5342 had ADSB-IN then PAT25 not having or not displaying ADSB-OUT could be relevant depending on 5342's cockpit display, the training of the pilots and their scanning.
5342 didn't have ADSB-IN so move along, move along, nothing to see, these aren't the droids you're looking for.

**Caveat. If the TWR display were using ADS-B for their updates and to generate Collision Alerts then the absence of PAT25 ADSB-OUT could be relevant.
But would the TWR ATC even know (or care) whether PAT-25 was ADSB-OUT capable. TWR ATC involves looking out the windows and judging the relative positions of aircraft.

Note: ATC display systems are not referenced in the NTSB Aviation Investigation Preliminary Report. This seems to be a glaring omission. So perhaps the NTSB are either very dumb or deceitful or both.

To further illustrate the focus on ADSB. Figure 1 Google Earth image with preliminary ADS-B data for flight 5342 and radar data for PAT25.
The ADS-B plots are 1 seconds intervals, the radar data are 4 second interval (as stated during US Congress Q&A).
So the focus is on the whizz bang ADS-B kit rather than what the ATC saw on their display.

There is reference to ATC radios, and 5342 was on frequency 119.1 MHZ and PAT25 was on frequency 134.35 MHZ. The ATC could've had them on the same frequency (changed PAT25 to 119.1 MHZ) but this would be abnormal. ATC Voice Switch systems like Frequentis, SITTI and Rohde & Schwarz typically have a frequency coupling, whereby controller broadcasts on multiple frequencies (2 or more) and voice communications on one frequency are heard on the other. In this case, ATC would broadcast on 119.1 MHZ and 134.55 MHZ and 5342 would hear instructions for aircraft on 134.55 MHZ, and PAT25 would hear instructions for aircraft on 119.1 MHZ.

Yes, visual separation is typically used close to an aerodrome where the ATC is applying visual separation to reduce the standard from 3NM to something less, 2NM, 1NM, or even less, depending on the circumstance which includes weather (included visibility), day / night, workload to monitor the separation, plus other considerations such as equipment.

I just wonder how many of the January Route 4 Helicopter plots crossing RWY 33 Approach (post 1346) were the result of ATC issuing a control instruction to change the track to closer to the shoreline or further over water.

Use of Route 4 during RWY 33 Approaches or RWY 15 Departures is possible providing a clearance limit is imposed prior to assigning relevant traffic, positive control instruction(s) and in the case of 5342, advising them of the relative position of PAT25 and that PAT25 would be maintaining separation from them.

Example for Route 4 southbound would be a clearance limit of Hains Point. Helicopter would be released past this point when there is no conflict (nil traffic) or assigned separation to avoid (pass behind). If there is a in-line stream of arriving traffic then Route 4 may not be available.

Sydney KSA has something similar for one of their helicopter routes - BONDI 5 (yep, named after the beach), delays may occur when RWY 07 is in use for DEP, or RWY 25 is in use for ARR. Further, the route is not available when RWY 16 PRM approaches are being conducted. Sydney KSA helicopter routes are in text form - TRACK TO..., TRACK VIA..., EAST OF..., and the INBOUND routes to Sydney KSA have a clearance limit in the clearance. A map display is very useful however it should be based on route descriptions. Perhaps the committee of 17 knows the history of the helicopter routes in and around DCA.

Since we\x92re discussing the DCA accident, let\x92s be clear about U.S. terminology as specified by 7110.65.

There is tower-applied visual separation . That is not relevant to the DCA accident.

There is also pilot-applied visual separation . That is what PAT25 requested and the LC approved.

As for the perfectly-safe visual separation, the DCA accident might have been avoided had the LC applied all of the elements of pilot-applied visual separation; i.e.