Airprox over Central Scotland

[OntimeexceptACARS]

Announced on several news channels today, the Airprox Board has listed a near miss between two aircraft to the north west of Pitlochry in Scotland on 23 June. I know this thread has been started on Spotters Corner, but perhaps the implications of a potential disaster on this scale merit this post?

I won't quote the embellished press reports, just point folks in the direction of the Airprox report here :

http://www.airproxboard.org.uk/docs/423/20130911-2013.09Reports.pdf

Curiosity got the better of me and I can see that the two aircraft were Lufthansa B748 D-ABYC enroute EDDF-KIAD and BA B744 G-BNLM enroute EGLL-CYVR.

One thing to add to the report is that press reports indicate that there "were up to" 1000 souls onboard both aircraft, though in reality likely in excess of 800.

[Exnomad]

Definitely not dodgy third world airlines then

[pigboat]

And probably communicating in impeccable ICAO English as well. :E

[LXGB]

Just read the UKAB report, then the story on the Sky News app.
Sky's spin department have exceeded even their own very high RPM on this one! :D

[PAXboy]

No mention in the article of TCAS.

[NigelOnDraft]

Degree of Risk C, ATC, pilots, visual sightings and TCAS all kept well apart...

Worthy of looking into into why. Newsworthy? Not sure...

[captplaystation]

Fairly routine loss of separation exacerbated by crews failing to follow fairly simple instructions, failing to utilise spatial awareness, failing to follow SOP's (advising TCAS RA) & then failing to operate AFS (I would imagine. . or cr@p hand flying? ) to provoke a 2nd alert.

All in all a bit shabby for 1st world legacy crew I would suggest.

[Ian W]

Degree of Risk C, ATC, pilots, visual sightings and TCAS all kept well apart...

Worthy of looking into into why. Newsworthy? Not sure...

It is not 'newsworthy' except for the over excitable tabloid reporting.

However, from a professional standpoint when a controller gives 'avoiding action' in Class C airspace the instruction should be treated in the same way as a TCAS RA - do not second guess, chat amongst yourselves on the flight deck, take a look out of the window to see if it's necessary - react at once and turn. From the controller point of view - ALWAYS expect your instruction to be ignored and watch carefully and reissue the instruction immediately it is apparent that it is being ignored. (I speak from experience in the same airspace). Unfortunately, the track smoothing algorithms can hide a turn on the controller display until 2 or 3 updates - that is a long time.

This has all the hallmarks of crews only half listening to their current controller and already settling into 'oceanic mode'. Perhaps..... As there were two 'avoiding action' instructions close together I think the first PF didn't fully hear them picked up half the second heading and thought it was a repeat of the instruction to his aircraft and turned onto it. The second aircraft PF heard the heading for the first and was not sure it was not for them - then heard their callsign in the second instruction and took the heading heard first. This is always going to be a problem with crews where PNF talks and the PF acts. It is obvious that both the PNFs read back correctly yet watched PF turn to a different heading.

All the masterly pilots on here who never make any mistakes - should think about this one.

[nippysweetie]

I suppose two heavy jets mixing up instructions to turn left or right is fine, as long as they don't mix up instructions to climb or descend when TCAS kicks in.

[NigelOnDraft]

I find it concerning when the pilots' "misunderstanding" (by both crews) is given as the "cause" when the root cause was 2 aircraft at the same FL on a converging course. The "RT was clearly stated on the VHF recording" which I suspect means a recording of what was being transmitted, prior to it going over the airwaves, maybe not clearly received, maybe blocked by Box 2 or I/c or Cabin chit chat etc.

SOPs likely permit at that stage only 1 pilot on the Flight Deck, maybe using speakers / microphone, when compared to busier climb/decent phases. As there were two 'avoiding action' instructions close together I think the first PF didn't fully hear them picked up half the second heading and thought it was a repeat of the instruction to his aircraftI think you are correct... when ATC order a Go Around it is "C/S Go Around I repeat Go Around", no doubt with good reason...

[HEATHROW DIRECTOR]

<<The "RT was clearly stated on the VHF recording" which I suspect means a recording of what was being transmitted, prior to it going over the airwaves,>>

Recording takes place simultaneously with the transmission going over the "airwaves".

[NigelOnDraft]

Thanks HD... my point was that the Airprox board seem to guarantee the quality of that recording as that as heard by each crews' ears...

[fenland787]

Thanks HD... my point was that the Airprox board seem to guarantee the quality of that recording as that as heard by each crews' ears...
I'm obviously missing something here, if the recording was made at the 'sending' end how do you know what was heard at the other end? Without a recording of the audio output from the receiving end that is?

[LEGAL TENDER]

I have no experience of working en route, so I shouldn't really comment. I just find it a bit strange that the a/c were converging and cleared to same level without being on headings. Especially in this day and age when we are constantly reminded to be "defensive".

The final numbers in terms of separation certainly don't make it headline news, but how the incident developed and how the holes in the cheese are always there makes it interesting and educational read.

[FlatBroke]

"He also noted that, during simulation training, avoiding action was only practiced as a result of a TCAS alerts, and not as a result of ATC instructions; this was an important consideration as to their potential familiarity with receiving, assimilating and actioning such RT instructions in a timely manner."

What?? I'm not having a go at either crews actions, but this statement by the board member surprises me. Avoiding Action instructions should be expected at any stage of flight surely, and from my experience precede/prevent many TCAS alerts. After all a change of heading so you don't hit something is not exactly the most challenging of tasks to assimilate and action.

Apologise for the thread creep here, but this would appear to be the correct course of action following an "Avoiding Action" command from ATC. http://www.ead.eurocontrol.int/eadbasic/pamslight-63EFDD3324DF66C9965BD622CDEBE06A/7FE5QZZF3FXUS/EN/AIC/P/099-2006/EG_Circ_2006_P_099_en_2006-08-17.pdf

2.2.2 Responses to ‘Avoiding Action’ instructions should not be made via autopilot vertical or lateral flight path control selectors

because, due to the design of this equipment, the turn, climb or descent that the Air Traffic Controller has requested and expects to see

actioned will be initiated too slowly to serve the needs of the moment.



It's maybe my gashness, but I'll be honest in that I have never responded to an "avoiding action" instruction by disconnecting the automatics as this would (I think) increase, what can become, a high workload situation. Likewise, I've never seen anyone else do it.

I often wonder if ATC expect us to respond as per the above AIC.

[Trackdiamond]

CNN is currently airing his "terrifying report" by non other than "Aviation expert" Richard:} Quest!!!

It all boils down to..CRM says Mr. Quest! I guess ATC/PILOT CRM is the new hot topic...or is it crew fatigue,Automation,inexperience AND CRM?

[eglnyt]

I'm obviously missing something here, if the recording was made at the 'sending' end how do you know what was heard at the other end? Without a recording of the audio output from the receiving end that is?

ATC recordings are recorded "off air" so the signal has been transmitted and received but they are only a record of what was transmitted and managed to travel between one of the transmitter stations and one of the receiver stations, usually a couple of miles or so. They are a good record of what the controller transmitted but only that, you need the aircraft voice recorder to be sure of what reached the aircraft and its relationship to other distractions.

[nippysweetie]

Converging aircraft means holes are lining up in the proverbial cheese. Two aircraft then making incorrect turns to increase rate of convergence is blowing a couple of huge new holes in the cheese.
Yeah yeah, 3 miles separation is great, but the 747 is still one of the fastest heavies and two of them swinging towards each other will gobble that distance up in no time, even if they're not approaching head-on.
Certainly would like to know reason for initial convergence path but much more disturbed by lack of insight into reason four experienced personnel on two flight decks were lulled into making a potentially catastrophic change of direction.

[Trackdiamond]

Was the word "say again" or "confirm" ever used by these convergent crew? It might well have been another Tenerife..or worse still..another Zagreb!

[OntimeexceptACARS]

Trackdiamond, I guess it depends how you view "worse still". 577 souls perished at Tenerife, 176 over Zagreb.

[Philflies]

Having just read the report it makes interesting reading. Amazed that both sets of crew took each others avoiding instructions from ATC. That's really not great PR for pilots at any level or qualification.

Yes TCAS was there as another level of protection so the risk is lower than that currently being hyped by the media. But to the layman you can understand a certain level of apprehension when aircraft instructed to avoid then increase their convergence!

Alas, for all the 'anonymising' of the report, the Airpox board does slip up a little by referring on one occasion to the 'B748'. Narrows down the operators somewhat.

[HOMER SIMPSONS LOVECHILD]

It's maybe my gashness, but I'll be honest in that I have never responded to an "avoiding action" instruction by disconnecting the automatics as this would (I think) increase, what can become, a high workload situation. Likewise, I've never seen anyone else do it.
Wow , how many "avoiding action" instructions have you received? I've got around 12000 hours in busy airspace and I've never received one. If I ever do I hope to follow my company SOPs and disconnect and fully expect my FO do the same!
Hopefully you are confusing a routine turn from ATC to ensure separation with a full on "Avoiding action!..." call. Time to get your head into that manual and clear that one up before your next flight perhaps.

[VFD]

I am going to jump in here with little knowledge.
I just find it interesting that we have two aircraft on a converging course that it requires ATC to require both aircraft to take evasive action.

My first thought would be that ATC should have only needed to vector, change altitude, or slow down one aircraft from the converging course long before the situation degraded to the point of requiring both to evade.
Hence, there would only be one set of instructions.
Again, I do not know.

[PAXboy]

May one guess that the CVR was not pulled - due to them being far from dest? So we'll never know what the crews actually heard. Only that could narrow down the cause.

Better to be talking about this than a prang. For both FC to pick up the wrong side of the TX is a VERY unusual circumstance. So unusual that it may not happen again for a significant time. Given the news, it will help everyone to think about it. Thus, a good outcome.

[Capn Bloggs]

I would hope that I'd notice a TCAS return, inside 10nm, same level, getting closer, and start asking questions...

[The Fat Controller]

VFD, you CANNOT use speed in this situation.

As for issuing instructions to both aircraft, that doubles your chance of one doing it correctly, sadly not what happened in this scenario.

[captplaystation]

Capn Bloggs

Like he said :bored:

[WHYEYEMAN]

I was always taught from a very early stage that if you hear the words 'avoiding action' or 'immediately' associated with any ATC clearance then you disconnect the autopilot and 'just do it'. I have never practised it in recurrent sim sessions however which is a shame as it would take less than a minute to do as part of a LOFT excercise.

[Trackdiamond]

I read you mate! But some walked away from that Tenerife cockup (PanAm)..a mid air collission is more severe..only in this case smaller crafts were the subject...Trident and. DC9...I was therefore referring to the severity rather than absolute numbers perished.You have a point though..relative speaking!

In terms of absolute comparisons..ofcourse it resembles the Tenerife disaster..similar types and categories involved...conflicting course, R/T cockups, possible CRM deficiencies...only major difference is..it took place is first world airspace with supposedly first class airline pilots..with ELP 6 transmissions no doubt! Its like we have not learn anything after over 3 decades! I think it is a good idea to incorporate a more realistic ATC/Traffic scenario rather than have SFI mimicking ATC..to have multi dimentional scenarios with conflicting ATC instructions for the crew to react to...to sharpen situation awareness...and during failures management phase at that!Also to have provisions in CVRs to be able to extract data during any requested time frame during the flight captured.

[Ian W]

I was always taught from a very early stage that if you hear the words 'avoiding action' or 'immediately' associated with any ATC clearance then you disconnect the autopilot and 'just do it'. I have never practised it in recurrent sim sessions however which is a shame as it would take less than a minute to do as part of a LOFT excercise.

I am amazed that a standard safety call from ATC is not practiced in simulators. And from comments here avoiding action is often second guessed by flight crew - whose lives are at risk due to their delay.

Most deconflictions are taken by planning the aircraft transits through the sector and the crew are unaware as they just follow the clearance they have received. However, when something goes awry the controller may have to act quickly and expects the aircraft to turn at once, there is no time for collaborative decision making and gentle FMC half rate turns.

TCAS is a really useful short term safety system but it will only see 'cooperating' aircraft that are transmitting/transponding on 1090/1030MHz. There have been mid-air collisions with one aircraft not transmitting. The controller almost always has a far better 'picture' of what is going on around the aircraft than the limited situation awareness of the flight crew who should not rely on TCAS to see everything. Time for second guessing is after the avoiding action is completed

[MCDU2]

We did ATC avoiding action scenarios a few years back in the sim. Our OPS manual now reflects that the AP is to disconnected in order that an increased bank of turn can be achieved. Our airline is all airbus and hence if you left in the AP at high cruising levels then all you would get is a gentle 1g turn. Interestingly enough we were briefed that a number of other airlines across Europe refuse to allow their pilots to disconnect the AP so to plan on an ATC avoiding action event to become a TCAS RA.

[fenland787]

ATC recordings are recorded "off air" so the signal has been transmitted....... they are a good record of what the controller transmitted but only that, you need the aircraft voice recorder to be sure of what reached the aircraft and its relationship to other distractions Right, thanks for that info, it's a very sensible way to ensure the record of what was transmitted is accurate and valid.

I appreciate it's probably not a factor in this case*, but it seems to me that if that was the evidence referred to in the report to imply the transmissions were received clearly then, as you say, without the aircraft voice recorder it's stretching it a bit!

*That said, something caused four people in two crews to make similar errors about what they heard...so there has to be a common factor relating to comms surely?

[Capn Bloggs]

Not watching the TCAS/not doing anything about it? Happens elsewhere too:
On 6 April 2012, a Boeing 737 and an Airbus A330 aircraft were on converging tracks at FL 360 (en route surveillance-based control). As the aircraft approached each other at the same level, the controller received a short term conflict alert (STCA) and noticed the aircraft were 5.2 NM (9.63 km) apart. The controller issued instructions to both aircraft to achieve vertical separation, which was established when the distance between the aircraft reduced to about 3.5 NM (6.48 km). See ATSB investigation AO-2012-048.
although in this case, "The controller immediately instructed the flight crew of the A330 to descend to FL350. The crew acknowledged and advised that they could see the traffic on their TCAS". Bit late for that...

Our airline is all airbus and hence if you left in the AP at high cruising levels then all you would get is a gentle 1g turn.
Not much of a turn! ;)

[bubbers44]

Sometimes you have to do what makes you feel safest. I was in a climb one day as a brand new FO on a B737 and at 3700 ft was told to level at 4,000 ft because of opposite direction traffic at 4300 ft. Knowing I couldn't do that at our rate of climb looked out the window and saw no aircraft so accelerated climb verifying no aircraft rather than pushing nose down into blind area. 20 seconds later passing about 5,000 ft approach said your traffic just passed below you at 4,000 ft. I told the captain what I was going to do of course but blindly following last second instructions from ATC may not always be the safest thing to do.

This happened in the earlly 80's prior to TCAS.

[Al Murdoch]

Lucky there wasn't someone above you at 5,000 I guess.

[RoyHudd]

TCAS never instructs turns.

TFN disaster involved full loss of life.

TCAS shows targets at long ranges.

The jeering at an airprox between 2 legacy carriers is being made by idiots and is misplaced. 2 so-called third-world carriers would have been much likelier to not rectify the original mistakes, and even bump into each other.

[Lon More]

From the report I'm a bit confused about the Sector management. It seems to me that initially the Sector was only manned by one controller. Is this SOP?
Überlingen and Zagreb spring to mind, everything chugging along normally, no problem for one controller, then it all goes wrong

[ROSUN]

Whilst recognising the need for anonymity in the report, it may have been useful to see if there was any similarity between the callsigns for these two aircraft.
Frequently I hear ATC instruct for example "BirdSpeed 231 ... " followed by "BirdSpeed 321 ..."
If the two companies alluded to earlier are the ones concerned they use a mixture of numeric & alpha numeric callsigns.
Also I'm not sure if one of the operators (if the hypothesis is true) readback method of callsign preceding the confirmation of understanding of the instruction causes any confusion to:
a) ATC
b) Other aircraft in the vicinity.
When this is heard on R/T it is almost as though it is a confirmation that because the callsign comes before the instruction it is deemed as a matter of fact that the instruction has been understood as the callsign was returned correctly. Well, my simple brain hears it like that!

[crewmeal]

I suppose now the Daily Mail have found out about Airprox they will report every incident reported such as:

Fighter pilot used weapons radar to avoid colliding with passenger jet | Mail Online (http://www.dailymail.co.uk/news/article-2470651/Fighter-pilot-used-weapons-radar-avoid-colliding-passenger-jet.html)

Sensationalism at it's best (or worst which ever way you look at it)

[bubbers44]

Even luckier I didn't level at 4,000 ft because we were cleared to 7,000 ft.

[Ian W]

We did ATC avoiding action scenarios a few years back in the sim. Our OPS manual now reflects that the AP is to disconnected in order that an increased bank of turn can be achieved. Our airline is all airbus and hence if you left in the AP at high cruising levels then all you would get is a gentle 1g turn. Interestingly enough we were briefed that a number of other airlines across Europe refuse to allow their pilots to disconnect the AP so to plan on an ATC avoiding action event to become a TCAS RA.

That will be really interesting to the controllers.

First - if you do NOT react at once disconnect the AP and make a standard turn you are hazarding your aircraft and the other aircraft and the passengers on both. But they use the AP to keep their management happy? :ugh::eek:

Second - If a controller has an aircraft report a TCAS RA while under their control they are removed from their position, have one way interviews with the supervisors and management. This is a career threatening event. All because the flight crew had a management directive to never fly manually?

Looks like managements should justify their case in writing to their passengers.

[slip and turn]

Climbing or descending into conflict still a problem in 2013 ? Classic in a safety system so predominantly reliant on exact vertical separation, what ? :hmm:

It seems the best post mortem timelapse pictures of any growing collision risk in controlled airspace are ATC radar. Radar control is also surely the best ante mortem antedote to this kind of ill - pity that the control AND monitoring gets degraded when there is some pressure applied to change a plan (in this case a pilot's request to climb).

As I read it, the report indicates the onset of this conflict was brought about by a pilot request to climb i.e. a request to the controller to change the controller's current plan for the safe flight of that pilot's aircraft. The report doesn't actually say this was the cause because as an operational event it was seen as routine. As always, it is what happened next which is in our faces.

Ultimately, the plan was changed as requested but clearly on clearance to climb it was being changed to a more risky one which had created ATC workload at the time to accommodate, and then was quickly followed by more ATC workload / monitoring / confusion / concern, then seemingly missed or misinterpreted safety communications, then pilot workload and probable confusion.

The official post mortem risk classifications applied are ICAO C or ERC 102. Take your pick, but essentially a routine request to (risk a) climb was mismanaged all the way into the tabloids today.

There's no question there are pants-down enough reasons for it to be reported in the tabloids. Seems to me the question is, as always, how better can classic pants down scenarios like this be avoided ?

The human condition/temptation to defend or blame individuals is of course not going to improve anything, but personally I don't buy that this was an everyday event to be noted in the database with a date and risk score.

[DaveReidUK]

Whilst recognising the need for anonymity in the report, it may have been useful to see if there was any similarity between the callsigns for these two aircraft.

"Lufthansa 418" and "Speedbird 87".

[obwan]

To the guys who invented TCAS your lifes work has been truly vindicated:D

[Eric T Cartman]

I find this comment from the report interesting from a "human factors" point of view :

ATCO(1) reported that his usual method of working was to put the electronic strips of conflicting traffic together and suitably highlighted. On this occasion ATCO(1) had not done this.

No explanation given as to why not. I'll bet my pension that if they'd been paper strips, he would have immediately put the strip holders together & cocked them out as a reminder......

[Ian W]

I find this comment from the report interesting from a "human factors" point of view :



No explanation given as to why not. I'll bet my pension that if they'd been paper strips, he would have immediately put the strip holders together & cocked them out as a reminder......

In the old days with strips they would not have been cleared to the same level. When the lower aircraft then asked to climb the radar controller would then have been given just those two aircraft to separate and would have watched them until they were clearly separated before giving them back to the planner.

Not many here will know what Redbrae and Gailes were :)

[Eric T Cartman]

@ Ian W
Gailes Type 7/14 blips were so wide, they'd never have got within 10 miles of each other anyway :)
I last did Area Radar in 1974 @ Manch but even then, if I'd not established both acft on headings before level changes, I'd had a sharp blow to the back of the head from my mentor. I'm sure there'll be many ATCO's who'll recall the examiner who 'chopped' many people for similar stuff ;)

[ZOOKER]

Wise words Mr.C. Also, as one of our training officers used to point out........"In area control, radar headings normally come in pairs".

[The Fat Controller]

If only I had the luxury of concentrating on just 2 aircraft to separate :ugh:

Comments as to how ATC worked 37+ years ago are not very helpful :mad:

This crossing scenario happens often and in this instance was identified, correct lateral avoiding action WAS given and IF the pilots had acted immediately and correctly, as the report states, separation WOULD NOT have been eroded.

Granted, the confliction was not marked on the strips, but it could just have easily been missed using paper.

I am valid on the sector concerned.

[AdLib]

So why didn't the controller give avoiding action to only one of the pilots? (= less chance of confusion over who's told what?)

And why not give lateral avoiding action to one and vertical to the other?

p.s. you may have noticed I'm not qualified in any aspect of ATC (apart from listening to it)

[PPRNkof]

50% of the incidents in the Airprox report involved military aircraft .....

[Lon More]

Comments as to how ATC worked 37+ years ago are not very helpful
Whether you like it or not the way we work today was shaped by those who worked then.
A lot of the advice my generation was given is still valid and worth passing on to today's students. Sadly, it seems that some of it wasn't, or fell on stony ground

[slip and turn]

This crossing scenario happens often and in this instance was identified, correct lateral avoiding action WAS given and IF the pilots had acted immediately and correctly ...But four pilots each with a brain supposedly plugged in to the radio transmissions of one ATC brain did NOT heed "the correct lateral avoiding action" which was "given". I think we might therefore be entitled to ask when is receipt / compliance with an ATC instruction a "given" (or not) ?

Is it for example:
(a) When a request to climb to a desired level is cleared without any cautionary condition attached about the new level having created a convergence problem ?
(b) When a sudden instruction to turn on the end of a busy series of transmissions to other aircraft is read back correctly ?
(c) When the aircraft addressed with the urgent instruction responds only with a transmission comprising just the digits of its callsign ?
(d) When the onscreen radar track appears to reflect the instruction given ?
(e) When the onscreen radar track appears to reflect the opposite of the instruction given ?

I don't think the report was particularly clear on all this beyond it being clear that the 5 brains involved in communicating and executing the instructions clearly were not ad idem (or was it 6 brains eventually including two ATCOs ?). At best it appears that at one point three pairs of brains were doing their own thing with each being unaware of what the other pairs were doing or expecting to be done.

I don't know if ATCO(1) realised it was a "given" when he ultimately cleared 747(2) to 340 or whether those posters reading the report have realised it, but once at the same level and using the data in the report it would appear that between 1252:00 and 1255:22 when low level STCA was triggered i.e. in 3.35 minutes the two aircraft had converged 14.5nm. That is a closing speed of 260 knots. In the next 38 seconds the aircraft closed a further 3.2nm i.e. an increased closing speed of 303 knots.

In the next 17 seconds before high level STCA alerted, a further 1.7nm separation was lost (that is a further increased closing speed of 360 knots or 185 metres a second with just 9000m left to close or just 48 seconds left until tracks cross).

Now when, as had already been seen in this incident, you factor in that the first attempt to instruct the aircraft to take avoiding action had taken almost a full minute to establish as not happening, we can begin to guess what colour pants ATCOs might favour for these frequent crossing scenarios. I am sure they are more aware of the hazards of the closing speeds involved than any civilian pilot. Question is, when they see one coming, how will they get the message across next time without the fail ?


I have to say, that "Resume own navigation" intruction that followed the first little fiasco was a little ironic (that's the fiasco up to about 1257 which warranted the description "airprox"). Own navigation seems largely to have been what was pervading from the moment 747(2) decided they wanted a better level and were given it!

Then, love-a-duck, just when some of us may have stopped reading the report and breathed a sigh of relief that it obviously all turned out ok with thousands of metres to spare, we get another STCA alert at 1258:20 seemingly caused by 747(2) having drifted down out of their 340 level just a couple of minutes after the first STCA alert! Perhaps they'd decided 340 was feeling a bit crowded / own navigation is the better part of valour etc...

So then, Part 2 of this buggers muddle then also takes the best part of a minute to resolve including two new ATC avoiding action instructions, one of which this time is queried and cancelled when the aircraft seem to have straightened themselves out (TCAS ;) ?).

Anyway, I really do hope this wasn't that typical "not newsworthy" day out some posters would have us believe it was.

[PPRNkof]

I actually think the third incident in the report was far more significant. The one involving the F15 Cowboy. The plane nearly lived up to it's name. The Strike Eagle.

[Annex14]

Fully agree with what you write, had my problems with some contents of the report too.
Well, I consider myself also being one of those "ATC Dinosauers", but as was mentioned before the basics haven´t changed !
Clearing two flights to the same FL and heading for the same fix at or almost at similar time overhead, was and is an absolute NO GO !!
I have my serious doubts that this conflicting clearance for FL 340 was coordinated correctly, as is stated in the report. Who in heaven would agree on such a flaw knowingly ??
I also see the second violation of separation as the more serious one. Hopefully, the two crews at least had each other in sight ??
Finally the question must be raised wether or not the reception of the avoidance clearances was as clear received and understandable as is assumed in the report. Obviously there is another "sleeping flaw".
Wether this was a "newsworthy" incident or not is not what raised so many comments. It´s the way those press and news sharks have prepared it for the common public that causes my anger too!!

[Eric T Cartman]

@ The Fat Controller
[QUOTE]Comments as to how ATC worked 37+ years ago are not very helpful[/QUOTE

I expect you've heard this famous saying : "Those who cannot remember the past are condemned to repeat it".

Not all the old ways are rubbish now - that's why us old codgers wouldn't do what ATCO(1) did .......

[maxred]

I actually think the third incident in the report was far more significant. The one involving the F15 Cowboy. The plane nearly lived up to it's name. The Strike Eagle.

Especially the 'when the climb rate exceeds 8000 feet/min:ouch::cool:

Mode C output is lost when rate of climb exceeds 8000fpm, and the member opined that this may have been the reason.

[MPN11]

I expect you've heard this famous saying : "Those who cannot remember the past are condemned to repeat it".

Not all the old ways are rubbish now - that's why us old codgers wouldn't do what ATCO(1) did .......

Along with others of the Older Generation, I find the concept of clearing both ac to FL340 with the intention of resolving any issues 'later' is anathema.

Lesson "ATC 1.01.03", I would suggest.

[slip and turn]

PPRNkof raises an interesting comparison which I take the liberty of paraphrasing as "does this incident between two 747s actually matter compared to other types of airprox ?":I actually think the third incident in the report was far more significant. The one involving the F15 Cowboy. The plane nearly lived up to it's name. The Strike Eagle.The ARM methodology(?) now in use by UK CAA gives the F15E/J41 airprox an ERC of 502 and the 747/747 an ERC of only 102. I assume there is supposed to be some steady linear progression of measured risk between these two scores and not some logarithmic scale as with decibel measurement :p

So, as maxred points out, the rate of climb of an unsuspecting F15E is enormous. Not quite as fast as any bullet but far more lethal projectile than any bullet if it hits you.

However, I wonder if the ERC classifications in any way take into account the obviously differing collision profiles presented by larger and smaller types i.e. if we assume in all cases the two conflicting aircraft are targeted to the same "aiming point" what is the likely grouping of the two hotshots when they punch their mark on target? Will the holes in the F15E/J41 target card ever be likely to overlap ? And even if they do, will one sneak through just in time to avoid the other? I think it is quite remote that two 19m long aircraft will be so unlucky as to punch the same mark even if using equally accurate navigational equipment.

However, take two 75m long projectiles and fling those at the target using the same kind of projectile accuracy then I would say there is a much greater likelihood of the punched holes overlapping. There are arguments that might suggest you need to use the relative airspace displacement volumes to calculate something useful, and others which might suggest a calculation based only on the collision area profiles presented by each typewould be more useful.

Either way I venture to suggest that it might be between 300 and 1000 times more likely that if you fire two 76m long 747s at each other from 20 miles or 6 miles or 3 miles that they will in some way hit each other versus a 19m F15 fired at a 19m J41. Anyone know if that kind of factor is included in the calculation of ERCs (which are supposed to provide a useful comparison of which incidents are the most important to learn from first I think!)? Any anti-missile missile scientists care to chip in with something more useful ?

Another factor in the comparative severity of risk might also be measured in terms of likely casualties both in the aircraft and on the ground.

And as we have also seen both in slow motion "why are they not complying / now what are they doing?" with the 747s and in "blink and you missed it" terms with the F15, the lack of adequate time for any intervention is surely a major risk assessment factor.

Does the recently introduced ERC system come close to getting the correct balance, do we think? Is there a corruption in the methodology which may mean that it too easily leads us to ignore lower score civilian operational risks because we are measuring them on the same page of an airprox report against what is essentially an enhanced military risk i.e. measuring both risks with a politically incorrect military mindset ?

Would it take five similar 747 on 747 airprox to gain as much of the CAA's attention as is warranted by the F15/J41 incident or is that not what those relative 102:502 ERC scores mean?

[Ian W]

If only I had the luxury of concentrating on just 2 aircraft to separate :ugh:

Comments as to how ATC worked 37+ years ago are not very helpful :mad:

This crossing scenario happens often and in this instance was identified, correct lateral avoiding action WAS given and IF the pilots had acted immediately and correctly, as the report states, separation WOULD NOT have been eroded.

Granted, the confliction was not marked on the strips, but it could just have easily been missed using paper.

I am valid on the sector concerned.

The problem here is what is called open-loop instructions as compared to closed-loop instructions.

With open-loop instructions an aircraft is told (as in this case) turn right heading (sic) 050. Pilot then reaches forward and selects 050 on the FMS. The controller may have in his head what to do next but nobody else does, least of all the crew. Similarly as in this case the lower aircraft was cleared to climb flight level 340 - controller knows something needs to happen after that but its an open loop as he may not have thought ahead or if he has it is only shown by cocked strips - or electronic highlight and an interrupt like a stuck mic or a controller relief and all can go pear shaped rather rapidly.

The trajectory based control systems that are just starting to appear in European airspace are 'closed loop'. An aircraft isn't put onto a heading or told to climb to a level, the trajectory which runs all the way to destination is given constraints (level, position and time windows) that it has to pass through. In this case the controller giving the lower aircraft a level constraint of FL340 would have received an immediate medium term conflict alert with the other aircraft as the new trajectory would be in conflict, so the controller would then have put in a lateral constraint on the trajectory that would have cleared the conflict. So the aircraft would now received a trajectory amendment with a climb and a deconflicting lateral constraint- not unlike an oceanic routeclearance.

Closed loop control is the way of the future systems. It will move air traffic management from the known traffic environment to the known trajectory environment with FMCs sharing their trajectories with the ground systems. It will also enable more efficient 'business trajectories'.

Experience gained 30+ years ago in that airspace being used to create more efficient and probably safer systems for the future.

[BOAC]

Could not see the answer in the report, but puzzled. Normally as you approach oceanic entry points you try to get up/down to cleared oceanic level. I gather both a/c had similar times at the same OEP. Why the climb request?

[Ian W]

Could not see the answer in the report, but puzzled. Normally as you approach oceanic entry points you try to get up/down to cleared oceanic level. I gather both a/c had similar times at the same OEP. Why the climb request?

I thought the same - but the Montrose sector is quite a way from the oceanic boundary. There is a full transition sector between there and the SHANWICK boundary. The aircraft could have been converging to RUGID then diverging one due West to ERAKA and the other North West to BALIX - I am sure Fat Controller could tell us.

[The Fat Controller]

Entry points were ATSIX and ERAKA.

The cross would have been at NEVIS if both aircraft were following their flight plan routes.

In this case the ATSIX traffic was going direct.

Montrose North map is here.

http://www.londoncontrol.com/scottish/ScACC_Sector_Information_Manual.pdf

We endeavour to give aircraft their oceanic crossing levels as soon as they ask for it, subject to traffic.

I am not going to make any further comment regarding the incident.

Edit. The link to the maps was just found by "Googling", some of them are considerably out of date, however Montrose North has not changed.

[BOAC]

Thanks, TFC - that clarifies nicely.

[MPN11]

Thanks Ian W ... That sort of thinking is what we old f*rts used to do, at least in the short/medium timeframe. Step-climbs cost fuel, I know, but at least they keep the aluminium separated.

T F C ... Thanks for the info. I think I understand your apparent need to step back from this discussion.

[Eric T Cartman]

Thanks TFC - no problem - I know NATS can get upset about postings on public "social media" sites like this. :ok:

[DaveReidUK]

The link to the maps was just found by "Googling", some of them are considerably out of date, however Montrose North has not changed.AIP map here:

NATS | AIS - Home (http://www.nats-uk.ead-it.com/public/index.php%3Foption=com_content&task=blogcategory&id=4&Itemid=11.html)

Scroll down to ENR 6.3.0: Upper ATS Routes (North)

[Annex14]

T F C
thanks for the brief additional information and the link. That answers some questions not covered in the APB report.
May be a wise decision to keep the pressure in the boiler at lowest possible level in such an incident.

DRUK
Thanks for the link to the AIP maps. Great help for someone not familiar with the airspace and routing situation.

[eglnyt]

The ARM methodology(?) now in use by UK CAA gives the F15E/J41 airprox an ERC of 502 and the 747/747 an ERC of only 102. I assume there is supposed to be some steady linear progression of measured risk between these two scores and not some logarithmic scale as with decibel measurement

Not really a steady scale. The method uses a matrix which has effectiveness of remaining barriers along one side and most credible accident outcome (if it progressed to an accident) along the other. The outcome maxes out with Catastrophic at 3 or more deaths so the only difference between the two scores would be the effectiveness of remaining barriers. It may have been developed since I last looked at it but my notes say 13 possible scores ranging from 1 to 2500.