Can a ready message really allow a pre-EOBT departure? I thought the Ready message only ever had an effect if you were given a CTOT after your EOBT, which allowed you to nab an earlier slot since you were ready to go.
Yes and no. Ready-messages can only be used when you have a CTOT and you want to let CFMU know you are either ready before the filed EOBT, OR the taxitime has significantly reduced which could result in a better slot but still after your EOBT.
Yes it has to be like that otherwise every airline would be using this all the time to jump the queue to the holding point 
They have already tried every trick and Eurocontrol has rigged their software to block these tactics – just like google has gradually blocked the search engine hacks
Sure Eurocontrol has to render dirty tricks ineffective. But if there’s no queue, you can’t jump the queue, and then why hold a flight on ground if there’s no congestion along its way?
It’s not like I’ve been destined to London Heathrow (but close 
)
But if there’s no queue, you can’t jump the queue, and then why hold a flight on ground if there’s no congestion along its way?
I think most slots are just artefacts of their software, or applying ATC rules like a max aircraft count of X in a given ATC sector even if you are at FL150 and the other 29 are at FL350. Here in the SE UK, rumour has it that most slots (which one gets mostly when flying south east) are caused by the Dover sector ATC limit. It has to be something like that because on an average long-ish flight, say 700nm, I’d be lucky to see more than a couple of airliners on TCAS, and mine has a 15nm radius and is set to display within 3000ft vertically. I simply cannot believe any slots issued to sub-FL200 GA can be anything to do with congestion.
I think it is important to understand what congestion is, or more to the point what sector capacity is. Your view is a bit simplistic Peter, as sector capacity does not have to be limited by physical proximity of flights in the sector volume.
Each ATC sector has a monitoring value, generally defined as a number of movements pr hr (Total, or separated into arrival and departures if we are talking terminal sectors) When that value is exceeded watch supervisor/flow manager/etc will consider asking CFMU to implement a regulation on the sector in question.
The monitoring value is set at the level the ATCO of the sector can safely handle traffic. If the airspace is non complex (mostly level flight) and small (horizontal/vertical) the sector monitoring value will be very high. If on the other hand the airspace is complex (lots of climbing and descending, as well as crossing tfc) and large, the sector monitoring value is lower.
Now, if you take low level sectors that you fly in Peter, they are often defined as GND-FLXXX, often as high as FL285. True, you will mostly fly below much of the traffic, but the controllers you talk to can still be busy, and you still have to be given a service. You have the right to talk on the R/T (block the freq…), and are hence part of the workload.
Myself, I work terminal sectors, and should you decide to transit the Oslo TMA at say FL150 (you are very much entitled to do so, and welcome) your transit will, in that airspace, create much more workload than one 737 arriving into Oslo in the same time period. (Non standard flights are workload drivers in terminal airspace) Can I promise that you would se anything on your TCAS? I think so, but you will at the least make me have to to conflict search and and/or use blocking levels on all arrivals and departures that cross your flight path for a time period. (You would be the odd one out)
Why mention it? Well, in some sectors piston GA flights are not much of a factor, in others they are very much a factor, even a problem. (And there are terminal sectors that have RAD restrictions for transits at lower levels, others do it ad-hoc in the air, which is a bad way of doing it)
Now, how to avoid getting CTOTs for flights in low level sectors with low density below say FL200? Well, create sectors that cover just airspace that has little CAT traffic, say below FL150?
Problem solved! ….now how to pay for them.
When the trajectory based system gets implemented, things will change, because the Network Manager can take into account of much of a conflict any given flight will be in any given volume of airspace.
Thanks for the great explanation, L-18C_Anders.
It’s a pity there isn’t a solution other than putting on more ATC desks, which at NATS are believed to cost about GBP 1M/year so obviously nobody is going to do that since most CAT traffic in the DVR area, on CD profiles into LGW/LHR, is still above FL200 out there (according to people with the ADS-B traffic monitoring boxes).
It’s bizzare because the slots usually more or less disappear. So one has to sit around and wait for the messages, and even if you get a 45 min delay you still have to be ready to go at the original EOBT because there is a fair chance the 45 min delay will shrink into a 10 min one, which is then irrelevant anyway because one can depart 15 mins early.
But Peter flying through a busy CAT sector low level also causes, in addition to his CTOT, CTOT for CAT traffic passing through the same sector, so there’s at least some incentive to increase sector capacity.
The biggest issue IMO is that the system is rather intransparent if you’re not an ANSP. I wouldn’t know, for example, how to find out what sectors I cross on a flight plan and where they are, what their nominal capacity is and what the actual foreceast is, etc. Most of the time it would probably be easy to slightly modify one’s flight plan to avoid an overloaded sector to escape a CTOT, but with the given tools it’s hard to do.
There’s the ATFCM Network Situation display on the NOP page, so if you’re determined, have a lot of time, you might try to cancel and refile manually (internally, autorouter can be told to avoid a sector, but this feature is not currently in the GUI). But to make this feasible, it has to be made much more convenient.
And no, it doesn’t look like the B2B FlowServices API does provide anywhere near enough information to handle this.
But Peter flying through a busy CAT sector low level also causes, in addition to his CTOT, CTOT for CAT traffic passing through the same sector, so there’s at least some incentive to increase sector capacity.
True
But think about volume, and how small the percentage of flights GA pistons IFR at the relevant levels is. The cost of keeping extra sectors would drive the unit rate up, and that cost is partly passed to the airlines. I cannot imagine that the few minutes of delay Peter and the like causes the airlines cost more than the increase in unit rate. Reason: There is a reason that low level sectors are generally of greater vertical extent than the high level ones in Europe: The service in the low part of that sector is done “for free”, as the traffic in the top pays for it.
Good point about the problems a GA pilot have when trying to file around sectors. CFMU and EC Network Manager is geared towards, and payed for by the airlines. Airlines (and ANSPs) have access to CFMU systems, and have access to all slot related messages (SAM, SRM SLC) In those messages you se what sector is the regulator, and the reason. I know many (most I guess) airlines have IT systems that easily displays regulations, and facilitates re-routing. Now, their auto re-route functions are not perfect either, and the results are often a source of amusement for us controllers. (I think ops-personell and pilots forget to actually check the re-filed CTOT free plan for added track miles. I´ve seen flights from Oslo to say Paris add 100+nm to their flight in Norwegian airspace due to a regulation is say Belgium, even when the flight exited Norwegian airspace on the original fix. Clearly George The Computer is not perfect.)
The service in the low part of that sector is done “for free”, as the traffic in the top pays for it.
The other side of that one, however, is that the 2000kt+ route charging thing was re-examined a few years ago and was decided to leave as-is, reportedly on the grounds that collecting the < 2000kg money would cost more than the revenue. Some NATS employees, writing on UK aviation sites, said they were very unhappy with that, which is a predictable symptom of the way cost recovery is done in the UK and what a political hot potato the “money” side of ATC has become here.
But it’s obvious that most people would just work around it… there is so much IFR in Class G (non Eurocontrol IFR) for which you would have to find creative ways to locate the people (especially difficult when Mode S is not mandatory for most VFR in Class G) and then bill them, and already most people doing that are flying “VFR” even for flights partly in IMC.
No matter what you do, somebody will always be paying for somebody else.
