View Full Version : Your slot's cancelled!

2nd Sep 2001, 12:47
Last night at PMI - slot delay of 1:30 minutes.
"It's a Barcelona/Bordeaux restriction - we can not re-route you so we're stuck with it" say OPS.
SUDDENLY the mobile rings, OPS; "It's ok your slot's cancelled. come on home".
Can someone understand this - the biggest stupidity in aviation. How does a slot delay of this magnitude disappear suddenly? What MORON is in charge at Brussels? Do they realise what these things mean at the aircraft end of the business???
Does any of you ever wonder what's behind all this? Who's gaining from this madness?
I am soooooooo tired of it all!

Electric Sky
2nd Sep 2001, 14:06

It is a strange system at Brussels sometimes. You can have a big delay that suddenly becomes minimal. I don't know what the reason for the French restrictions last night. However, from previous experience, at night the Bordeaux restrictions are quite often caused by sectors being collapsed usually due to staffing problems. What this does is double the work of a controller as he/she has twice as much of an area to look after. This subsequently reduces capacity and gives you your large slot delay. If they manage to get extra staff to come in then they can revert to normal and this would explain why a big delay becomes slot cancelled. A ready message does a similar thing as this looks for missed slots and "gaps" in capacity that you could take, giving you an earlier slot time.

Hope this explains things a little.

ES ;)

2nd Sep 2001, 14:16
Twistedfirefighter I couldn't agree more. The whole European slot system is unbelievable.

Someone correct me if I'm wrong but, you call for push & start at the appropriate time for your slot, and you are given clearance to do so, then whilst taxying there is some airfield delay - let's say a broken down vehicle in the way for example - which delays you beyond your slot expiry time, you may still continue because you would have been ready on time had the airfield delay not happened!!!!!!

What was the point of the slot in the first place then?

This certainly was the case a couple of years ago when I visited Eurocontrol. If it has changed can someone please let me know. :confused:

2nd Sep 2001, 14:26
And another thing. I was there last night too. The quality of the Spanish controllers is declining. Every time someone called ground for a clearance they were asked to say again their callsign. They don't even understand our callsigns anymore, even though it must be written down in front of them. The whole place is run by monkeys.
Sorry didn't mean to detour from the subject, but just HAD TO!

2 six 4
2nd Sep 2001, 15:14
Twisted - The Brussels operation is the administration for the participating countries which impose the flow control in the first place. If your slot is cancelled then either the regulation has reached the end of its required period or has been withdrawn. Your company Ops department should be fully aware of exactly what sector in which Area Centre was delaying you. If their action was unreasonable get the company to ask for a reason.

If you don't challenge you won't get answers. We have to answer questions every day in the UK - don't see why others shouldn't as well after all they are public servants. :rolleyes:

Devils Advocate
2nd Sep 2001, 18:02
Actually the whole show is run by the Central Flow Management Unit (CFMU) of EuroControl in Brussels.

Reading between the lines they use some sodding great mainframe computer to manage the ATC 'flow', i.e. because if you want to connect to it you have to use an SNA compliant connection - where SNA = mainframe type networking.

Now in one of my other guises (i.e. I've got two hats) I'm presently involved in connecting my airlines Ops Department to EuroControl's Slot Management computer - and you would not believe what a nause it is to get the network hardware to function (or perhaps you might).

That said, EuroControl will soon be making available (about a month, or so) connection via TCP/IP (the internet protocol - which you're using right now to access this site).

According to the CFMU literature it initially should be able to handle the viewing & requesting of slots, but it won't be until next year (apparently) that you will be able to ask "if I re-route, can I get a better slot ?" type questions - via this TCP/IP browser based connection.

Of course with browser based TCP/IP connectivity you could use a laptop on the flight deck to connect to the web via a mobile phone, or better still a wireless LAN, login to CFMU with your corporate account, and then manage the slot / routing yourself - to say nothing of having a quick surf of PPRuNe too !

The Guvnor
2nd Sep 2001, 18:57
Where's Avman? :confused: :confused: He's PPRuNe's man at Eurocontrol - and I am sure could provide both the reasons for these problems - and hopefully, when we can expect them to end! :D :D

2nd Sep 2001, 19:08
Don't ask me. I must call them about 15 times a day to try to improve these slots.
It really depends if the guy wants to help you or not. :confused:

2 six 4
2nd Sep 2001, 22:16
Devil. The actual flow control is imposed by each ACC, If they decide at no notice to cancel beacuse they have not been monitoring demand then they are the ones to blame for the sudden change.

Devils Advocate
2nd Sep 2001, 22:40
2 six 4, are you saying that CFMU have no control over airways load and mearly broker airway space on behalf of the individual ACC's ?

It's just that that seems to be at odds with what seemingly happens when you apply to CFMU for a new slot, and / or put in a 'ready message' ?

Just curious..............

2nd Sep 2001, 23:11
Devils Advocate

That's exactly what 2 Six 4 is saying and he/she's right.

The individual ACCs advise the CFMU of their sector capacities, firstly on a strategic basis (i.e Ops Normal) and secondly whenever conditions require a different capacity to exist. It is these figures which are fed into the Wurlizter and are used to calculate globaly whether you are restricted or not.

If you are given a slot, it will always be possible for your company (and the CFMU) to find out which sector is causing the most penalising delay on your route. If that sector then changes cirumstances and ups it's acceptance rate, then your details can be fed back in and the whole process started again. However, it doesn't mean because your most penalising restriction has been removed that you now get a clear run at things. That's because all the less penalising delays which were 'hiding' behind the biggest one now come into play. They are still there and have to be taken into account.

The CFMU have no say over the capacity an ACC sets and no influence on the guys at the coal face. As they have only a sparse knowledge of the airspace and no knowledge of the ATC procedures and staff levels and capabilities at the ACCs, there is no way that they could.

I am not sure if any non UK ACCs make use of it, but in the UK we do have constantly updated information from the CFMU on the pain that the UK is causing (using the CASA Delay Monitor). This will flag up aircraft in the system where 15 minutes or more delay is being imposed with the most penalising delay being due to a UK sector. This gives us a trigger to take a look at individual flights to see if we can do anything for them. For example, we may suggest to the operator that he refiles below the restricted sector, or if it's UK interenal flight, we may speak to the adjacent UK ACC to see if it can take an extra flight over and above the regulated capacity. Of course this is not quite so straightforward if the flight is going beyond UK airspace since although we remove the UK penalty, the CFMU then has to recalculate all the other restrictions through which the flight will have to pass. Your 1 hour delay in the UK might still turn out to be 58 minutes if that's what Paris are regulating. It's just that the Paris restriction was 'hidden' behind the UK one before !!

Devils Advocate
3rd Sep 2001, 00:37
Thanks loads 10W - it was obvious, I suppose, but it's always nice to hear it straight from somebody at the coal face.

Almost hate to ask (but namesake requires it) but could you (or anybody) answer another question, i.e. when they have the annual 'slot' conference (usually at some swanky resort, somewhere nice and hot) what are they doing, and how do they do it ? Also, how does this then manifest itself into SSIM's ?

Curiouser and curiouser ......

gul dukat
3rd Sep 2001, 03:07
Just to give you flying types a little insight ....today I had a slot revised BACKWARDS three times as an aircraft was ready to start .I phoned Brussels flow and told them I was IGNORING their slot ...."you can't" she said in a nice dutch/croatian/english what the hell accent..what do you suggest I said? taxiway is blocked !! why should I take it in the neck for you? your call .....result slot BROUGHT FORWARD ....aircraft had to speed up !!!WE are as PI$$ED OFF as you .....I feel like a total gob$hite for telling you your slot has changed .......but blame the guys at eurocontrol ...NOT the guy on the ground at PMI ....or ...BFS!!! THERE! outed myself!!!! :mad:

3rd Sep 2001, 11:49
gul dukat

The guy in PMI was blamed for crappy English and a huge inability to understand a simple callsign like for instance BLUESTAR *** or JMC *** or Britannia *** ...

3rd Sep 2001, 11:59
Devils Advocate. Have a play with
null (http://www.cfmu.eurocontrol.be/CIA/anm1.html)

gul dukat
3rd Sep 2001, 12:59
Mike !!

"They don't even understand our callsigns anymore, even though it must be written down in front of them. The whole place is run by monkeys.
Sorry didn't mean to detour from the subject, but just HAD TO!"

I was talking about slots not the deviation you embarked on so I reckon you are being unfair on me to pull me for something I did not comment on ! :rolleyes:

4th Sep 2001, 03:27
What I cannot understand is why the big operators out there don't join up and demand that the CTOT computer be shut down.
This is not only a question of time and $.
More importantly it is a question of safety.
How many of my colleagues out there can honestly say that you have never hurried through your preflight checks in a way that you otherwise never would, just to be able meet that ##@@**** slot.
Yes, we shouldn't let it affect us, but we all know what the consequences of a missed slot-time can be ( eg. duty time exceedance followed by crew-rest at the out-station while the pass. spend 10 hrs in the terminal ) and you will be the one explaining it all over the PA tomorrow.
I'm going to stick my neck out and say what I think this is really about : A number of jobs in Brussels for those who nurse thier CTOT software like a little baby.
Pull the plug.

Hand Solo
4th Sep 2001, 03:44
Yes but think of how many TCAS RAs we'd have as some maxed out controller tries to sort us all out with no means of reducing the flow rate. Do you really want to get airborne then find you have to spend 30 mins holding enroute because the next sector can't or won't accept you?

4th Sep 2001, 04:30
Hand Solo
In the best of worlds all software is efficient, optimal, fast and without bugs.
I might be a pessimist, but my experience with software is somewhat different.
If we lived in the best of worlds I'd happily accept whatever CTOT imposed upon me, knowing that our precious airspace was utilized in the best way imaginable.
I have a feeling though that we're not there quite yet.
I get your piont ; but I'm not at all convinced that the chap/dame who is responsible for the CTOT software has any reason of beeing proud of it.

4th Sep 2001, 05:11

The CFMU aren't the ones who set the flow rates, it's the ATC Centres. All they do is broker them on everyone's behalf. Think back to the bad old days where there was no central agency and each ACC had to speak to the next one who had to speak to the next one who had to speak to the next one who said, sorry, there's a delay. Meanwhile half an hour or more has elapsed and it's back to square one. At least with the software, warts and all, the answer is almost instantaneous.

If you think it's a waste of time having flow control then you need to go to one of the busy ACCs in Europe and sit in on a regulated sector where the ATC controller is hanging on by his finger nails. And then tell him that there's another 20 or so coming from now on since there are no slots any more !!

CFMU is not perfect but it is sure as hell better than aluminium showers over parts of Europe.

[ 04 September 2001: Message edited by: 10W ]

2 six 4
4th Sep 2001, 12:15
Devils A. Don't think you got an answer to your question about the annual slot bash. I'm afraid that is airport capacity not en route daily capacity. Different animal.

However if someone decides to take their local ATC staff to an exotic destination to discuss local slot times .......... :p :D

4th Sep 2001, 12:45
Right, lets pull back a little and look at the larger picture. Controllers are maxing out, too many aircraft flying in limited airspaces and the whole thing is set to get WORSE. So what's going to happen?
I think that we as a human race couldn't be more stupid, selfish and evil. What we MUST understand is that just in order to "keep" a certain route we increase frequency on it with little silly sized RJs which now clog up the system and doing a great deal of damage to all of us. Airlines will eventually be made to "take turns" to a destination and only will be allowed to fly on certain days of the week, while others on alternate days. (Great for aircrew)!
This stupid greedy situation is what needs addressing right now. Intelligent conferences followed by intelligent decisions and implementations and the REDUCTION of traffic is what's needed.
Not the reduction of aircraft sizes!!!!!
I for one don't think we will get there. I think we'll just carry on as stupid as we are and end up like the M6 every day.
So good luck to all the boffins and software scientists amongst you - it's the big picture we must understand.

[ 04 September 2001: Message edited by: yorkunt ]

4th Sep 2001, 13:51
I agree with you completely.
In an attempt to foster competition on routes, slots at the major London airports for example have been given to newcomers to operate routes. The result of this has been, on many occasions, a reduction in the size of the aircraft on a particular route with another small aircraft of another carrier also operating the route at a similar time. The result is no benefit to the passengers (same number of seats offered) but increased congestion and delays, as well as environmental costs.

I suppose that at least it keeps pilots and controllers in a job.

Kerosene Kraut
4th Sep 2001, 14:04
It might fill the sky with smaller a/c but this is what a working market mechanism should look like for the customer. La Guardia promoted slots just for smaller new entrants. Please don't hope that just keeping the current situation will make things better. ATC in Europe is some serious organisational issue not that of true airspace capacity. Get mil-airspace reduced and unite centers. Well, easy to claim I know. :rolleyes:

Scottie Dog
4th Sep 2001, 15:13
Devils Advocate

Whilst I am not qualified to provide an answer to your questions with regards to the Annual Slot conference, I will have a go on the basis of information that I have access to.

Firstly, I assume that you are referring to the IATA Schedules Conference that meets twice a year – in June and November.

To quote from the IATA World Scheduling Guidelines, ‘The purpose of this voluntary assembly of both IATA and non-IATA airlines worldwide, is to provide a forum for the allocation of slots at fully coordinated airport (Level 3), and for the reaching of consensus on the schedule adjustments necessary to conform to airport capacity limitations (Level 2).’

With regards to the allocation of slots – which as you are aware, are based not just on runway availability, but also apron and terminal capacity – these are based on firstly historical slots, and then the remaining slots are placed in a pool for use by new entrants and airlines looking to extend an existing seasonal service to a year-round one.

All of the above only relates to the allocation of slots at the airport and does not take into accounts delays that may occur as a result of ATC, staffing or operational problems – if only we lived in a perfect world!

As you will see from this, there seems little connection – on this occasion - between your question and that of the problem being raised in this forum.


Scottie Dog

ATC Watcher
4th Sep 2001, 16:58
It is quite amazing to realize how little aircrews actually know about ATFM. Mixing up airport slots with ATFM ones will not help you much in your quest to understand the big picture.
(Now I have to defend the CFMU ! Big change )

(To the Guvnor : Avman is on leave but is not, and by far the only man in Eurocontrol in this Forum.. By the way I am still waiting for the contact in AAA you promised me months ago, I still need those DC8 engine fuel igniters knobs... )

Back to our subject :

I am amazed by the first post by Twistedfirefighter who called it "madness"to have his slot cancelled.. Which means he would have rather liked to have the CFMU kept its original CTOT just because it was issued, instead of releasing him once the ATFM restriction that caused his delays was no loonger active ?
ATFM restictions can be put in place for various reasons, capacity is one , but often it is staff shortage ( as explained already) but also equipment failures. Those comes without warning, and when the systems comes back it is also generally sudden. So ACC ( the Centres) lift the restrictions at once, and then the CFMU try to cancel as many CTOT as possible...
Complaining about this may send the wrong signal to CFMU operators my friend....

Incidentally do you prefer to hold en route or in the ground , bearing in mind that if you all hold en route, you will increase the delays for the others on the ground ?

4th Sep 2001, 21:51
As somebody mentioned earlier, we continually monitor the effect that any restrictions imposed to protect "our" sector are having. If, due to staff shortage or temporary airspace constraints, we are relying on these slots to even out the traffic flow, we are still mindful of the effect on the users. For example, if the restriction is causing an average 20-30 minutes of delay, then an aircraft picking up 90 minutes will stand out "like a sore thumb". If we are the only restricting sector, and often we aren't, then it is likely that we will attempt to "take an extra one" to prevent some customer being penalised excessively. I thought we were being proactive and helpful. It appears from the tone of this thread that I am just being a nuisance. Perhaps I should let delays just "take their course" without trying to help? Comments please....

Devils Advocate
4th Sep 2001, 22:10
Just gotta say a big 'THANKS' to 10W, 2 six 4, ScottyD, and ATC Watcher, for their replies above - guys it's genuinely helpful in setting out the 'big' picture as to who's doing what, where, and when - one day I'll hopefully have half an idea as to what's going on - till then, please keep it coming ! :)

4th Sep 2001, 23:03
EOBT 12.00

SLOT 13.17

Pax in the terminal are informed about the atc restriction.
at 11.45 New slot time arrives: 13.09, in any case boarding was planned to begin at 11.50.

At 12.10 all pax - 2 are sitted, and the slot is again changed to 12.32.

in many airports you should be ready to go at slot - 20 min. in this case at 12.12.

you have 2 minutes to find the 2 happy shopper or to unload their bags.

In this case "who removed that slot????", i will shout

hope this helps to some people some other point of view.

Grandad Flyer
5th Sep 2001, 00:29
I have another suggestion to throw into the pot. So you had that slot on Saturday night at Palma. Well, I happen to know that there were a lot of aircraft headed for Ibiza that night. There was a whopping great thunderstorm over the island and a lot of metal ended up diverting to Palma. Many were stuck for a couple of hours before the storm moved away from the airport and aircraft could get back over there.
This, I would think, could have caused some screw ups with slots. All those aircraft going IBZ-PMI and back again, and then IBZ to the UK, probably on the same routes as the PMI crowd heading back to the UK.
Just a thought.

5th Sep 2001, 11:38
ATC Watcher, Numpo-Nigit

- Is it absolutely necessary to give a reply which even when is partly informative - contains some stupid personal remark like:

"Which means he would have rather liked to have the CFMU kept its original CTOT just because it was issued, instead of releasing him once the ATFM restriction that caused his delays was no loonger active"

"Perhaps I should let delays just "take their course" without trying to help? Comments please...."

I think I'll let the rest of the pilots here to judge the above.

5th Sep 2001, 11:59
Your CTOT may have come forward because your company has listed your flights as RFI - Ready For Improvement. This means that the flow computer will automatically issue an improved CTOT regardless of whether or not you have had an REA - Ready message, sent.

It is therefore your responsibility to either get all your pax on board in time (difficult when there is so much shopping to be done!) or ask your company not to list you as RFI and wait until you are ready to send the REA.

As others have said, flow measures do sometimes come and go very quickly which can cause problems in knowing whether or not to board pax. Surely it is better to get them rounded up an hour early rather than depart an hour later than you could because you couldn't find them in time? This would also permit airports to remote park you so that the gate is freed up, the tug can be released and you're in pole position should an improvement materialise.

5th Sep 2001, 13:47
Cossack beat me to it!

The old Ready (RDY) message has been split into two.

Companies can now send a Ready For Improvement message (RFI), which will improve the slot to no earlier than original EOBT + Airfield taxi time (16 or 20 mins at LHR, depending on departure runway). i.e. it is assumed that pax will be boarded to make the EOBT. I'm led to believe that this is usually automatically done, unless there is some obvious reason not to (tech problems etc etc.)

ATC can send a Ready (REA) message, which can now improve the slot no earlier than the present time + taxi time, even if this will be earlier than the original EOBT.


5th Sep 2001, 14:47
In addition, we can, if you are remote parked or on the way out to the hold, reduce the taxi time as well to bring the CTOT that bit closer. This only usually works when you are subject to minimal delay and are perhaps ready early.

Another reason for getting those pax on!

5th Sep 2001, 15:09
While sitting in Athens day befor yesterday waiting for our start clearance after another slot delay I was told by our handling agent that there is a local restriction of 37 movements an hour. Any body heard why, or if this is in fact a kosher statement.
Was kept entertained in the meantime by lady in Speedbird getting an earful from Lady in Ground control about unco-operative behaviour. Very thin lips all round. To be fair I felt that Birdseed had tried to help but somewhere along the line there had been a simple misunderstanding about rolling forward a bit more during/after pushback.

5th Sep 2001, 17:14
Cossack, do your slot times also take into account 'Time to insert into sequence' and 'time to remove rom sequence'?


5th Sep 2001, 19:00
TRS is set at 5 minutes. But there have been numerous occasions when an aircraft has started for one CTOT only to receive another much later one. These we log and ignore.

TIS is set at 10 minutes. This plus our normal 15 minute taxi time gives us a 25 minute period to give us all a chance at meeting a CTOT that is issued.

I wonder how many crews are aware of their company's policy with respect to RFI. This can only be suspended by the company. ATC cannot help here.

5th Sep 2001, 20:37

You really must learn to calm down or your blood pressure will cause you to fail your next medical!!!

I really don't see that the remarks made by ATC Watcher or myself were either "stupid" or "personal". We are both struggling to understand how to make constructive use of whatever influence we may have on the slot allocation system.

Taking sentences out of context does nothing to help. My question, addressed hopefully to the wider world of pilots, was to attempt to find a simple rule to guide my attempts at being customer-facing. There seems little point in me "meddling" with the FMU system to bring forward a slot if it causes such anguish to the crew and despatchers on the receiving end as has been described above. I would like some advice as to what is and what isn't a useful intervention, but I see no need to make personal attacks on other contributors.

Once again, comments please....

5th Sep 2001, 20:49

How about this - you bring the slots nicely forward and let us worry about being ready for flight. I understand how hard you might be trying, but if you can, then you should.
If we made a bad decision and haven't got our pax in time for a new slot, then someone else will have to have it.
Now there's is a USEFUL "intervention" if there ever was one. Isn't there?

5th Sep 2001, 21:27
In defence of my colleagues in ATC, may I remind those at the pointy end that we are there to get you on your way ASAP.
YOU, "should" have ALL your pax on board ready to go for your ETD. That your CTOT is not the same...ho ho does NOT mean that you can be lax in loading, and YES YES I DO know that "handling agents" can be a pain.
BUT do not anticipate a delay, 'cos you just "might" get one
we aim to please, it keeps the cleaners happy

6th Sep 2001, 12:03

We have 10 mins for both TIS and TRS, and I do agree with you about how some crews are not aware of the RFI/REA. I often get crews call up 20 mins before the slot for start, even though they've been ready for half an hour but haven't called up because 'company have sent a ready message' - RFI.Gonzo.

6th Sep 2001, 19:14
Chiglet: From the handling agents viewpoint: we're not all "pains" as you put it. Where I work we always endeavour to board pax ASAP even if we know there's a bad slot; this is OK where it's the airline's stated policy to board on time/ASAP, but some airline's pilots refuse to board their pax even at the risk of missing the slot should it improve. Spanair are a prime example of this; they sometimes insist on not commencing boarding until T-25 minutes on a late slot even when we tell them that this mightn't be the best option! And then the slot generally comes forward halfway through boarding! You can't win. I can see where such pilots are coming from when it comes to not wanting to have pax on board for an hour before departure, but they don't seem to appreciate that slots do improve sometimes. Incidentally on a more humorous note, I dealt with an IL76 cargo flight a while ago that filed a flight plan at 18:30 and ended up with a slot at 21:25 the FOLLOWING evening. Ouch!

6th Sep 2001, 20:34

Thanks for your most recent post. I always try to reduce delays through "my" sector to a minimum consistent with safety. I was worried that, from my interpretation of your initial post on this thread, this was causing serious problems further down the line when I was able to significantly improve a slot. Now that you have made it clear that we both have the same objective, as I originally believed, I will continue as before in trying to get you airborne asap.

Thank you.

9th Sep 2001, 12:01
In reply to gul dukat's gripe of the 2/9/2001.
I was the flow manager who was responsible for the revisions to your flight that night so I'll explain.
The Flow management position at London Air Traffic Control Centre advised us that they were short of staff for the night shift - one of the controllers had gone u/s in the car park on his way into work. Unfortunatly he was one of only two who held a validation for the Seaford sector that night. The result was that they had to physically close the sector every two hours for 30 mins to give the other guy a break (legal requirement).
Because of the short notice the flow measures had to be applied immediately with the dreadful results that you experienced.
Normally we do not revise slots for flights within 30 mins of departure, but if the airspace is closed its closed, full stop.
We then worked as fast as possible, with London, to move traffic that did not have to fly through that sector, and improve flights into free slots so created. London also agreed to move some traffic in flight. If you received a revision it would have been as a result of these efforts.
So don't blame the guys at Eurocontrol, don't blame anyone. We are all trying to do our jobs to the best of our ability and sometimes that involves dealing with shitty situations such as the one you experienced.
SO, I've stuck my head above the parapet now, but I'll be happy to try and answer some of your questions. There are some angry pilots out there, but we can talk........

9th Sep 2001, 12:20
In reply to FlapsOne's entry of 2/9/01.
If you are going to miss your slot because of an unforeseen problem at an airfield, ATC at that airfield are obliged to call Flow for a new slot (or an extension to the existing slot).
We then have a number of options.
We check the load in the critical sectors, if there is room we agree to the extension. If there is no room, we can still agree to the extension and move another flight in the affected sector to a different slot (by swapping to your old slot for example).
In exceptional cases where there is a load problem in the sectors involved (too many flights) or its too late to move any of the other flights in the sector (already airborne for example)we may have to refuse the slot extension, but that really is a last resort, after all missed slots are wasted slots.
To answer your question, the point of the slot in the first place was to protect ATC from overdelivery of traffic- that's dangerous. The reason you can still go anyway even though you've missed the original slot is because the faceless bastards in the background (like me) are beavering away to try and make the whole thing run smoothly.
If you prefer we can send you back to stand to wait for another slot, but I don't think that will make you feel any better (or us).

9th Sep 2001, 18:31

Thanks for the info. It's helpful to understand what goes on behind the scenes.

When you say:

Normally we do not revise slots for flights within 30 mins of departure

do you mean that you don't make the slot later within 30 mins of departure, or that you don't make it earlier? My limited understanding of the system is that a slot shouldn't be moved earlier unless a RDY or RFI has been sent. For those of us without ops departments, it would be very difficult if we had slots moved forward without a SIP -- how would we find out?

gul dukat
9th Sep 2001, 19:21
Flow man Thanks for that .The person who gets it in the neck is the controller at point of sale ..IE ME!.I will obviously accept delays and have done ,in this case however ,it looked like I was taking the pi$$ .I am aware that there is a much bigger picture but what about letting me know what the problem was instead of just stuffing on delay followed by delay ..a DD message with a few lines on it EXPLAINING to the guy at the airfield would be nice .The DD as you know will alert the assistant or controller to the urgency of the situation and make him feel less like a numpty when he cancels push and start or in my case threatens to send a guy back to stand!

9th Sep 2001, 20:14
In reply to Bookworm's question:
Slots will not normally be revised within 30 mins of departure unless a flight has been declared "ready for improvement" (RFI) or if ATC tell us that the flight is ready to accept any short notice improvement in which case they send us an REA message. This normally contains a minimum line up time.
The RDY message died earlier this year and is no longer used - ATC were often unable to cope with short notice changes to the slot, hence the new system.
If you do not have an Ops department and your flight is in SIP wanted status any slot improvement proposal will be sent to the AIS at the departure airfield or to the originator of the flight plan.
Of course all of this goes out of the window for emergency "stop the traffic" type situations.
I hope this helps clear things up for you.

9th Sep 2001, 20:32
To ALL aircrews/handling agents and airline ops peeps. Phone ATC at your unit and ASK FOR A VISIT!!!!! [99 times out of 100, you WILL be accomodated although perhaps not quite "right away"] and see for yourselves the nuances. In return, perhaps ATC could [daren't say should] reciprocate. :D
we aim to please, it keeps the cleaners happy

10th Sep 2001, 12:15
All you well intentioned ATC-ers.
An example from yesterday.
STD - 13:45
CTOT - 14:00 Brilliant.
Push and start 13:45
As we pushing back, ATC - your slot has just become 14:29 what are your intentions????
Well we're already pushing, surely we're in the system so we could just take off? Nope. sorry. Carried on pushing, then held remote followed by 2 more slot changes, eventually left at 14:10.

ATC-ers should we not be allowed to continue once we have pushed for a slot within the allowed time. Even if this means revising your capacity in our favour? I found yesterday's ATC game somewhat difficult to stomach. Then of course on our way, there are huge periods of silence on the French and Swiss etc... frequencies. (I know so London might have been busy, yippee).

So come on guys, don't bother to explain this to me, just get some common sense into this anti-aviation system and get us all airborne once we've pushed ey???

10th Sep 2001, 20:12
If Twisted Firefighter wants to e-mail me some details or stick them on this bulletin board I'll find out what happened. I can't be more accomodating than offer his own personal investigation service. Give me some hard facts and I'll respond.
I need aerodrome of departure, destination and off blocks time. I'll find the rest.

10th Sep 2001, 21:03

I wouldn't bother. With his attitude he neither appears to want to believe what he's told, nor listen to it.


Pot calling kettle, pot calling kettle, come in kettle.

You come out giving the lecture to ATC Watcher and Numpo Nigit

- Is it absolutely necessary to give a reply which even when is partly informative - contains some stupid personal remark

This from someone who starts the thread off with a comment like

What MORON is in charge at Brussels?

Perhaps I can use one of your quotes for myself next.

I think I'll let the rest of the pilots here to judge the above

Did you ever ask your Ops people to find out what these problems were due to ?? They can you know, as they have access to the CFMU equipment which will show exactly what the slot was all about. And then if you don't believe the reason, or have a gripe, you will know exactly which Area Control Centre to call up about it. They would be happy to try and discuss the situation with you and let you know what is going on.

On last minute changes, let's take an example. Doesn't happen every day but not too uncommon now and then to have a runway blocked, could be a burst tyre, aircraft come off the paved area, whatever. So the airfield and the TMA around it may put on restrictions - very very suddenly. You're just pushing when this happens unfortunately. And you want us to still let you go ?? Meanwhile everyone else plays it your way and wants the same. Only thing is, there's no runway any more so there's lots of holding and diversions taking place. But hey, you're all pushed back so we should just let you get into the system which is going to become clogged up. Can't have an anti-aviation system whose prime goal is the safe and efficient movement of air traffic getting in the way after all. An extreme example perhaps, but do you know this wasn't what happened in your second situation. Oh hang on, I apologise, looks like I just wasted your time.

So come on guys, don't bother to explain this to me

Fortunately for all the other pilots reading, people in ATC and the FMU WILL try to improve slots where they can, WILL cancel regulations as soon as they feel it's safe to do so, and WILL try to explain to operators the rationale behind them if enquiries are made. It is the least that professionals would do. I am sure that the vast majority of you would wish us to continue to do so and accept the reasoning provided for individual or generic cases, which are providing assistance to a better operation in the greater scheme of things. For some though it will always be a case of me, me, me, and sod everyone else and their problems. :(

So, if you really want to see how it all hangs together, visit your local Flow Management Position at your local ACC, or visit the CFMU near Brussels Airport. I would like to think that you will find it very educational. It might also demonstrate that we don't know which aircraft Twistedfirefighter is on and that all his woes are not personally directed at him by his 'friends' in ATC and the CFMU ;)

11th Sep 2001, 11:37

PPRuNe Bashaholic

Sorry I couldn't read your post earlier matey, I was delayed by ATC.

Regards T.

11th Sep 2001, 14:51
Flowman et-al,

Your comments are very interesting, after following all the pages of this thread it appears that a lot of the problems directed at the ATC community are in error. There appears to be many problems blamed on ATC when it is individual company practices with respect to delays that need reviewing at local levels. Concering PMI in general, not the night in question, I was told that they have a new policy on a/c arriving "off-slot" i.e late. The subject a/c is given the last available departure slot, and is allowed to disembark pax only on arrival. 2 hrs before slot inbound bags offloaded, check-in can open, once i/b bags offloaded, o/b bags can be loaded. All seems v.v. strange to me, and have bee uinable to determine its accuracy. What does wind the PMI atc up is pilots not obeying the instructions for obtaining start clearance, and when people cheat calling early etc. In paphos this is not permitted as the guys in the follow-me vehicles observe the a/c and pass by radio the stauts af any a/c requesting start.

Question for Flowman or other ATC ers what are the implications at the CFMU of cheating as some operators do, i.e calling for start early then not being ready.


11th Sep 2001, 15:30
TwistedFirefighter, your e-mail is "blocked by the administrators", so here's your reply.

Okay, at 1340 Geneva alerted us to an impending overload in their sector between
1500 and 1600 UTC.They say it was due to aircraft climbing above their FPL level
(they would not previously have been counted) and requested that we reduce the traffic
to the correct number. This was done at 1344, the usual 30 minutes parameter was
overridden otherwise there would have been an insufficient reduction in traffic.
This is when you received your first slot revision.
At 1346 EGBB TWR sent an REA message telling us that you could be airborne within
10 minutes. This prompted the two subsequent revisions as the machine reallocated
any vacant slots. Why there were vacant slots in such a situation is not clear, I
would have to look at the messaging for the other affected flights (about 50 of them),
but a Zurich sector was modified at about the same time- that could have moved some
of the other traffic.
Just to explain the first bit, we have a big problem with aircraft being filed below
regulations and then climbing into them. Some do this deliberately, queue jumping
if you like. Others use it as a legitimate way of avoiding delay, unfortunately if the
crews are not briefed accordingly they will accept climb offered by other ATC units (who
are normally unaware of problems which may be several sectors down the line).
Most of the overloads we investigate are due to either this problem or aircraft
departing outside slots. Don't forget that even the existing slot window of -5 +10
in a sector with a capacity of 60 per hour can deliver 75 flights (10 from the
previous hour, 5 from the next hour).
So the closer the system gets to its limits the more rigid it becomes. We either have
to accept less flexibility or higher delays overall.

Davey Clark
12th Sep 2001, 04:23
Im finding it hard to comprehend some of the postings on this thread. FlapsOne, what do you think slots are for in the first place, just a bit of a rib-tickler for ATC guys to use to get some laughs? They are there to protect YOU from getting into a situation where you might be less than 100% safe. I'll say that again, 100% safe!

The restriction which is being applied may apply at some sector thousands of miles from your departure aerodrome, so "good on" the neddies who apply that to you as a departure slot time. Maybe they should give it to you as an arrive at position XXX between time ABCD and WXYZ, and let you work the numbers out for yourself, maybe not.

The bottom line is... keeping it ALL - SAFE. No more, no less. Would you fly your kite above Vne in turbulence just to keep YOUR customers happy..I hope not.

Keep a handle on it guys, ATC is not there to restrict, it is there to TRY and keep us all safe.


12th Sep 2001, 19:19

Thanks for the explanation.
For now, I must turn to yesterday's events and try to sort my head out over that.
I'm dropping out of here, p'raps we'll debate slots when they become THE important thing again one day.


13th Sep 2001, 04:55
Others use it as a legitimate way of avoiding delay, unfortunately if the
crews are not briefed accordingly they will accept climb offered by other ATC units (who
are normally unaware of problems which may be several sectors down the line).

I understand you have a problem with this, but don't you think this is the ATC unit's problem rather than the operator's? We regularly refile below a restriction, and I don't think a crew needs to be briefed about that particular ATC problem: if they get their CFP at FL290, they know what to expect and their fuel will be planned accordingly. If the controllers want to give them higher anyways, then why should they refuse? These things make us save money.
Furthermore: why do the AIMs we regularly receive ask the operator to fly the filed levels when this is something that can easily be imposed by the controller? This also eliminates the problem of one controller not knowing that 2 or 3 centres further there is a problem at a certain level.
I suppose I'm missing something here, but you have to admit that at first sight it's quite strange to say the least. Any comments are welcome.

13th Sep 2001, 20:03
It all seems inconsequential after recent events, but we have to carry on as normal or the bastards have won.
So, for fadec_primary_channel the answer is straightforward, cheating results in a medium term reduction in capacity.
If an ACC declares a capacity of 50 flights per hour and regularly receives 55, it won’t take them long to reduce capacity to 45.
The most common causes of overloads in ATC sectors are aircraft departing outside their slots, and flights turning up at other than filed levels.
Bear in mind as well that even with the existing slot tolerance of -5 +10 that a sector with a capacity of 60 flights per hour can in theory receive 75 flights; 10 from the previous hour and 5 from the next hour.
Increased flexibility would have to mean a reduction in capacity and therefore increased delays.
CIV5C: What you say is partly true, the controllers could keep you at your flight planned level, but that too is very inflexible. Many aircraft operators are perfectly happy to brief their crews according to flow requirements, I don’t see why you have a problem with it. The alternative, as Davey Clark suggests is to give you an “arrive position XXX at time YYYY and FLZZZ”.
That strikes me as being much more cumbersome. Correct me if I’m wrong...