Sector overload (UK)

[BOAC]

The latest edition of Chirp has a comment [P5 (2)] about rapid-fire ATC transmissions on the LAM sector and it starting to happen on the DTY sector, where no sooner has the (wrong) aircraft acknowledged the instruction than a new one is issued to another a/c, with around a half-second gap. The intended 'cleared' a/c is unable to get a word in to correct the error and it is suggested that the controller has not 'heard' the incorrect read-back. It reports of multiple attempts to contact as well due to R/T traffic load. I have experienced this R/T congestion myself on many occasions.

If you guys and girls are THAT stretched, what can WE do about it? Will MORs help? Obviously where a controller has not listened correctly to a read-back an MOR will NOT be a 'good thing' for that controller, so any other ideas? CHIRP has called for MORs, and suggests they should have been filed in the past. It sounds as if you need some help!!:eek:

[30W]

As it happens, as a pilot, I filed an excessive RT loading MOR against LACC S25 on Tuesday afternoon. The sector was running 'bandboxed' with S26 and the loading was FAR too high in my opinion.

If you feel the same, then file an MOR on it, please do. Often controllers file 'overload' reports, only for the investigation to conclude that an overload didn't exist purely because the sector flow rate was not exceeded.

If we as pilots file when we feel the traffic loading on a controller has been too high, then we support their case (in my opinion).

My issue was that at 3pm in the afternoon we shouldn't have central London sectors bandboxed!! I had NO CTOT though on my route through the sector, but RT loading within it was excessive, with non stop transmission.

I await the formal response of course, and don't wish to prjudice its findings, but:-

1. Why was the sector bandboxed? Staff shortage?? If so, then why no proper flow on the sectors.

2. If staff available, then why was the LAS allowing the sectors to run together.

Personally I suspect the first, but remain open-minded.......

30W

ps. I have come close to filing one on COWLY/WELIN also. This is bandboxed FAR too often with high RT loading!!!!

[Over+Out]

I am one of those LTMA Controllers you mention. To me, on the ground, it seems that sometimes we are talking continuously, most times it is because we are very busy on that sector and it is fully split.
Sometimes though it is a very small busy period which we can see will be over shortly. Flow control sometimes seems to be 'Bunch Control'
Is the R/T as busy in other places in Europe/USA?
What do you pilots think?

[30W]

Over+Out,

No, I know of no other airspace that has RT loading like some UK sectors.

Maastricht runs flow rate equivalent if not greater than the UK, but RT loading is not so high in my experience. If the French and many others ran with RT loading like yours, then you'd find them on strike by the end of the day rest assured!!

In my examples above I can assure you that both LACC and LTCC sectors WERE combined. I know the sectors well enough to know the traffic flows and SA's for each, and know straight away when combined operations are in progress.

Sometimes there is just no gap in ATCO transmissions for a pilot to 'get in' without fear of overstepping the controller - making congestion worse as he then has to repeat his stepped on Tx.

Surely this is not either good or right? It seems to me MOR filing is the only way of drawing attention to it.

30W

[5milesbaby]

Often controllers file 'overload' reports, only for the investigation to conclude that an overload didn't exist purely because the sector flow rate was not exceeded.

Wrong, if a controller files an overload report then they are without question overloaded even if the sector flow rate wasn't exceeded. If it was a case of the sector flow rates determining overloads then when we try out a new higher flow rate and an overload occurs, you'll be told it was within rate and the rate not adjusted back down. Don't forget that controllers are all just human and that on different days we can handle different levels of traffic just due to how we are on that day, and another controller could handle more or less during the same session due to personal competence, so if anyone feels overloaded its not a personal 'failure', just maximum level reached. Overloads do often occur due to bunching as mentioned above, but also due to presentation from other sectors, late offers of traffic, and even bad RTF management on both ATC and Pilot sides. One of the ones I had delivered under sector capacity over the hour period, unfortunately 50% of that sector flow rate came together on the same route 10nm wide within a 20 minute period, at one stage all a/c were within 25nm of each other, and all needing level changes.

With regard to sectors being bandboxed or split at certain times of the day, you'd be suprised at the times sectors get busy ie S15/16/17 (DVR in old language) at 10:30 in the evening, and Clacton at the same time with all the Ryanairs and Easyjets returning to base mixed with the last European and all Middle and Far East flights departing. If the sector looks like it should split then normally it will. However sometimes there is little warning and we can see its a short burst so by the time the split happens all the traffic has passed.

If you as Pilots feel that the frequency is far too congested then I would say you should file an MOR. If only one or two are filed then nothing will ever change, but from reading others threads too, its becoming far more common that the RTF is getting saturated. What happens if you have a Mayday? Yes by selecting 7700 we'll see you have a problem, but then what about all the other tracks as you are dealt with? If you file an MOR and the controller has missed a readback or two, then its not nice knowing that they will be investigated, however they may not realise they had done and by finding this out they will only learn how to be a better controller, as incidents improve our experience and make us better next time. The only thing I do ask is that you do not tell the Controller over the frequency you are filing (had this twice now) as it congests the frequency, can stun/anger the controller, and is much better to give the centre a call upon landing for a quick word with the Watch Manager/Supervisor. Even though the RTF may go quiet after a busy spell it doesn't mean the situation is over, we could be on the telephone or giving a handover to a fresh controller and unneccessary interuptions only hamper the smooth flow.

[30W]

5miles,

I fully agree that an overload HAS occured should any SC feel he has been overloaded. I suggest only that the subsequent investigation tends to suggest that an overload sometimes has not ocurred - or at least thats what colleagues of yours down south tell me.........

Perhaps, if staff levels are sufficient, then sectors should be split at ALL times during normal daytime shifts?? It would stop the getting 'caught out' by a sudden 'bunch' ?

Only opening the topic for debate..........

Regards
30W

[5milesbaby]

All I was indicating 30W was that even if the subsequent investigation says that traffic levels were in the pescribed limit, that an overload has still occurred just due to the SC saying he/she was overloaded. Overloading can sometimes be with very few aircraft, just a super-high complexity.

I wish we had sufficient staff to split all sectors at all times of day, but the shortfall is well documented on PPRuNe. The way sectors work is that they look at the demand for each and work out which combination for bandboxing works best. Some staff members can do more than one area so 'borrowing' one for a while can also be done, but not for an entire shift. To give you an example, the Dover/Worthing sectors can currently be split into six different radar seats, or 7 but procedures for one split (DVR high & low) aren't currently available. Now if S19/20(Hurn) is above flow counts as well as DVR and LYD bandboxed (S15/16 & 17) during a half hour period, but both cannot be split simultaneously due to staff, then it may be just S19 that needs flowing as the demand on S20 is low, and then DVR/LYD can be split. Hence your departure from EGBB/EGBE/EGNX (my guess at where you fly from) is free flow, but all those coming back have slots although you are all worked by the same controller. I cannot give you any technical reason why this seems to work better, it just does.

[Mr R Sole]

30W

You must of been practicing on LC if you know the SAs that well! :D

[30W]

5Miles,

Thanks for the examples..........
Just when will NATS mangement achieve sufficient staffing levels?? (How long's a piece of string I know!). They have been short for many years now, one would hope the situation was improving..........

Mr R Sole,

I have got LC yes, but if only I had time to play!!
Have visited LTCC/LACC/ScOACC many times, as well as Maastricht and a fair few other foreign units. Have always had a keen interest in ATC matters. Have also worked on CAA airspace working groups, so UK airspace is generally known and kept up to date with. Mind you, doesn't take a rocket scientist to work out if southbound in S25 that it's bandboxed with S26 when clearances such as 'descend FL220 level HEMEL' etc are heard!!

Cheers
30W

[5milesbaby]

We wish we knew when staffing would get to being what we need, however we do get by very well with what we have. The problem at the moment is that many of the "old boys" are hanging up their headsets, so its as if as soon as one validates another retires. The college has also gone through a huge change with the courses hindering recruitment for a while so hopefully soon that will start to kick in and begin the improvement. However there is only a finite number of students that we can train at the same time, due to seats, number of mentors, and mentor competency (ie. they also need time on their own, currently 50%). With the traffic levels rising so much its becoming harder (and longer) to get students through, but slowly but surely we are getting there. The other thing to cause a problem is the increasing number of sectors we now have. Soon the West End at Swanwick will become 7 sectors from the current 5, plans are in place for the Hurn sectors to increase, TC just seem to get more and more airspace, the last over Clacton, and I would expect more of this to happen. Will LHR adopt new positions when T5 and the new tower opens? Does Manchester have more positions with the new runway now open? These all need more staff, not only to sit there working but also extra to cover breaks. To give you an idea, for 8 seats open we need 11 staff to cover breaks so we do not go out of hours. If the seats open becomes 10, like the West End and Dover/Worthing can do, the number needed becomes 14. When the West End gets resectorised they could have 14 seats open, so thats 19 staff needed. At the moment its rare to get any more than 12 on the grouping, so we need to find 7 more staff PER WATCH (5 watches) just for the West End. Some of this can be eased with the AAVA's (overtime in English) and the tactical deployment of staff, ie (Theoretical)West End goes 10 seats from 12 to 2pm, but back to 6 for the rest of the afternoon, so 14 staff needed becoming 9 at 2pm. The 'spare' 5 can then be moved to Hurn/Central sectors dependant on where the traffic delays/levels are, and once they quieten again, back to the West End for a final flurry. This is where the LAS's get together with flow and work out who to flow when, and who to deploy where. Hope thats not too mind bending, we're so used to this happenning now that its almost second nature, but hopefully things will ease very soon. :ok:

[Carbide Finger]

11 for 8 doesn't work for prolonged periods. It's just about workable if every one takes EXACTLY 30 min breaks and there is no training.

[jabberwok]

5miles,

Your description of the increased sectorisation is illuminating but does this work? I can see that it would result in controllers handling fewer aircraft but surely this would be counterbalanced by the increased demand on time for co-ordination/handover? Even if it works for now there would become a point at which further sectorisation becomes less efficient and once the optimum is reached what next?

The second thought that runs through my mind is that this overload thread is splitting into two camps. On one side it is concerned about actual controller workload and, on the other side, about R/T overload. The two are connected but not exclusive.

R/T overload is the more apparent of the two to aircrew. Last week I tried for some time to establish initial coms with ATC (north of CLIPY) but R/T was solid. In the end ATC called me! OK, maybe I'm not so fast on the trigger finger these days but it isn't nice having to battle for talk time.

R/T congestion results in other undesirables too. Rapid fire speech on the controllers part because he's got too much to say in too short a time frame. The same from pilots because the atmoshpere encourages it (we are aware R/T is busy and try not to hog the frequency). Controllers not able to wait for readbacks because they have to move on to other decision making transmissions. Readbacks that you hope are being listened to despite the controller working like a one armed paperhanger and probably has his mind on other tasks. I confess I don't like it and I am sure that both pilots and controllers are uncomfortable when it gets like this.

I wonder if the whole concept of R/T is now too slow for the increasing load on ATC systems. At a simple level I'm thinking of the wasted R/T time when two people key the mike together and block the frequency - and the subsequent "say again" needed to sort this out. It can mount up to a good chunk of R/T time.

At a more serious level I wonder if our current R/T procedures require a more serious overhaul. Verbal communication is slow so maybe we need to develop an even more highly concise language than we currently use. There isn't a lot of garbage in what we say right now so its a matter of getting what we need to say out a lot faster.

Maybe it is even time to consider alternative technologies to replace or enhance current systems/procedures. Maybe some sort of audio control that prevents anyone transmitting once someone else has keyed a mike - surely better than listening to ten seconds of slush that is invariably going to require repeating..

Just thoughts gentlemen but we all know that the present way we do things are not going to survive for much longer. The current solution of reducing sectors can only be taken so far and is a short term remedy. It's time to start looking at the whole system.

[250 kts]

Welcome to the world of a commercial company running the ATC system where the regulator fines the provider if delays go above a certain level and managers' bonuses also depend on few ATC delays.

This is the way it is now in NATS. The operational ATCOs are encouraged to shift as much traffic as possible and restrictions are only put on as an absolute last resort. Yes the new system at Swanwick allows us to handle far more traffic than we could at West Drayton with few,if any,more staff. I have every sympathy with you not being able to get in on the frequency and I often find myself "calling" the traffic onto the frequency. There is no doubt that this problem will not be going away soon as the alternative is that traffic is restricted and hence delays will occur-not good for the operators and certainly not for those bonuses.:confused: :confused:

[5milesbaby]

Carbide Finger, 11 for 8 may be tight, but having worked it on a regular basis for the last 2 summers I know how it works. At present trainee debriefs do not constitute regulated time, therefore are considered to be part of a break.

jabberwok, the re-sectorisation is happenning. More sectors will be introduced on the West End, and the trials have proven how much more traffic can be shifted. Its not a case of opening them all at the same time, but increasing the combinations the sectors can be run in. This does increase co-ordination in a way, but with a dedicated planner with every sector using the electronic co-ordination will not pose a problem in the sense you talk of. The Hurn sector is being reviewed for a re-sectorisation within the next 3 years, one of the thoughts is to introduce a new sector to channel the RTF accordingly, so that those flights overflying London that get big routings to readback are on one frequency, and the TMA arrivals on another. Early days yet but its looking at sorting the problem you are on about. As for the long term future, Mode S will vastly reduce the need for RTF as eventually datalinking is to be introduced. Although in very early stages I believe that Australian ATC and Maastrict have been doing some trials, so the RTF will only be used for the unusual and requests.

[PGA]

oke guys, totally different subject, im sorry for that, but where do I get the CHIRPS from. Im a new UK based pilot, and don`t know where to get them, please help

[055166k]

No big secret here. Sectors are regularly subject to planned overload of 10%, and short-term superloading of 30-50%. If you are still alive [mentally speaking] after several months at the hands the promotion-hungry or the downright inept then you get a circular from the ATC OPS, which says that based on operational experience the basic sector flow-rare will be increased by 10%.........then the whole cycle starts again.
Couple this to all the verbal "mini-legal-contract" R/T crap that we are obliged to say and you get busy frequencies...e.g. Do you really need all those "expect levels" when they're written on the chart?
As for route information there is a lack of intelligent use of current facilities; use abbreviated routes in the same manner as those on STARS/SIDS, and use VOR broadcast if necessary.....it would be an "area" version of ATIS.

[Lon More]

PGA Try a Google search on CHIRP. I found a few, including this (http://www.cirp.org/), but I think This (http://www.chirp.co.uk/new/default.htm) is probably the one you want

Lon More, here before Pontius was a Pilot or Mortus a Rigger

[bekolblockage]

As a matter of interest, are any of you guys measuring the actual R/T loading on each sector ?
What % R/T loading do you consider overloaded?
We have some software under evaluation here and find the results staggering on occasion.

[055166k]

bekolblockage
Read a couple of papers on this some years back, apparently there is good evidence that sustained R/T occupancy of more than 70% leads to loss of "picture" due lack of available thinking time.
Results are failure to monitor read-back, clipped transmissions, incapacity of global scan function, and, after prolonged exposure.....increase in stress level and potential for communication failure within operating team [known as "blinkers"], as well as system inability to react to unusual or emergency situations.
Long term exposure believed to be a contributory factor in staff sickness; although some of the trial subjects were found to deny this because it may have seemed to be an admission of lack of ability...[ the human factor ].

[BEXIL160]

My colleague 055166k is spot on.

RT loading is indeed a significant issue and one not taken seriously enough IMHO.

The only thing that will change this is a Flood of MORs from Pilots, or (hopefully not) an Emergency Situation that is adversely affected by high RT loading. I hope the first would prevent the second.

There have been a few papers on RT loading. The one that has been refered to also recommended that there should be an 8 second gap (yes EIGHT!) between controller transmissions. I can't really go along with that, as we'd never get anything done, but there should be time for a least a 2-3 sec gap i would suggest.

thoughts anyone?

Rgds BEX

[bekolblockage]

Thanks guys.
As you say 055166k, we need to get rid of the mundane ramblings that are regurgitated 35+ times an hour on our sectors, such as STAR clearances and crossing requirements, via other means e.g. CPDLC.

BEXIL160
Wow-8 seconds between transmissions -I wish we saw 8 seconds free per minute on occasion!

[av8boy]

055166k and BEXIL160...

R/T occupancy of more than 70% leads to loss of "picture" due lack of available thinking time.

Do you happen to have a reference for this? I’d really like to look at the studies…

Speaking only for myself (and addressing jabberwok’s thoughts—”Readbacks that you hope are being listened to despite the controller working like a one armed paperhanger and probably has his mind on other tasks…” as well), I find myself MORE keenly attuned to readbacks during extremely busy periods. It’s part of a rhythm you develop when you’re really, really busy—a sort of focus that’s unlike anything else I’ve ever done. In contrast, almost 30 years of this have shown me that (again, at least for me) the slow periods are the ones that are most likely to cause problems. When I started out an old-timer told me that light traffic would bite me… he said, “if you’ve only got two aircraft on frequency, they’re always going to conflict.” On top of that, when it’s slow you’re able to have other things on your mind that take away from SA. When you’re busy, that’s just not possible.

I’m certainly not saying that it’s better to be so busy that nobody can get a call in, and I support anything that can bring more sanity to the profession. To put it more clearly, I agree with what's been said about needing to make a change. I just wanted to make a personal observation about the “inattention to readback” issue and ask about the studies cited…

Dave

[BEXIL160]

Hi av8boy,

Reference? No, lost it. It was an IFATCA study, so worth asking them. They have a whole lot of this stuff.

One of the times that we seem to be most prone to error is immediately after a busy session or push of traffic. Errors don't seem to happen as often as they "should" when we are VERY busy, probably because we are concentrating and are "Stepping up a gear".

When the push is over, we tend to relax a bit, and "take our foot off the gas". And therein happen many of our errors.

Rgds BEX