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FPL submission time

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FPL submission time

Old 26th May 2008, 17:33
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FPL submission time

UK AIP ENR 1.10 says

3.4.1 FPLs should be filed a minimum of 3 hours before Estimated Off Block Time (EOBT) for North Atlantic flights and those subject to ATFM measures, and a minimum of 60 minutes before EOBT for all other flights.

In practice, IFPS response is as close to instantaneous as it could be, and there doesn't seem to be a problem with filing a FPL, watching it appear on the CFMU Internet App, and calling for start if there's no slot. (I know I'm at the back of the queue for slots if I file after slots are allocated, but most flights aren't regulated.)

So what are the relevant constraints of other parts of the ATC system? For example, is there still a need for strips to be printed in an ACC or are they all electronic and instantaneous too? How long does that take after reception of the FPL?
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Old 26th May 2008, 19:01
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If the FPL is perfect, the flow of information is more or less instantaneous however it still takes a few minutes for strips to be printed and the info' to be assimilated.
You shouldn't rely upon this as the be all and end all as occasionally, as with all systems, hiccups occur.
However, if your FPL has one little error, it will be rejected by the IFPS computer and thats where the hassle for everyone starts.

A good example is an experience I had last week.
A pilot wanted to fly IFR to Brussels, the route in the UK was outside CAS, joining Dutch CAS at the boundary. His Ops filed his FPL on his behalf 10 minutes before the FPL ETD, but due to airspace restrictions in Holland, one error at the end of the route caused the FPL to be rejected. It took 35 minutes and a lot of goodwill from IFPS staff for the problem to be rectified.

Had the FPL been filed 60 minutes prior to ETD, the problems would have still been resolved, but he would have got away on time.

The above happens all the time in one form or another, it appears that Ops departments and occassionally, individual pilots never learn and eventually they find that the massive goodwill given by IFPS and ATC staff runs out.
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Old 26th May 2008, 21:03
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However, if your FPL has one little error, it will be rejected by the IFPS computer and thats where the hassle for everyone starts.
It's a good point niknak. For the purposes of my question, please assume that the FPL is ACKed without amendment by IFPS.

With IFPUV available, there's little excuse for filing routes with errors these days. I haven't had a FPL rejected for, literally, years. I was thinking more of the case of having arrived an hour early and wanting to bring forward the flight when preparation is complete, by cancelling and refiling.
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Old 27th May 2008, 18:19
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The only risk of cancelling and refiling is the imposition of a slot time.
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Old 27th May 2008, 19:37
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The IFPS rules are clear that a minimum of 60 minutes are required for receipt of the IFR FPL before your EOBT. If you comply with that, then you can expect no difficulties.

That said, if you submit with less than the minimum then it could be possible for your flight to still operate without any problem whatsoever. This will normally happen if:

a) you are remaining within UK airspace and not joining the Airway system, or,

b) you join the UK Airways system at a point at least 1 hour after you filed the plan.

For other flights, you might also get no problem, assuming the FPL has been inserted in to the UK ACC system automatically and no errors have been detected which require manual correction (in the UK system). It will also depend on the appropriate ACC sector then having the flight details in front of them to make their ATC decisions to deal with your flight when they find out about you.

If luck is on your side, then you will probably find that you are on of the 99% of flights which file with less than the required submission time and are able to proceed without any delay. The problem will be if you are one of the rare flights whose details have not made it in to the ATC system in time for your call, and you are then in the lap of the Gods. Or more correctly, in the lap of those who have the ability to assist you in your non compliance Such people may not always have the capacity, or the inclination, to do so. It's just the gamble you take.

Flights crossing international boundaries can also run in to 'beaurocratic' problems if the adjacent ACC has not received and/or processed a late submission. Some air defence agencies can get a bit worked up about such flights !!

If you want to depart early on a filed flight, you can do so 15 minutes prior to the filed EOBT without any problem, provided you are not affected by an ATFM slot. If you are at an airfield with an ATSU, they will check this for you. If you are at a non ATSU unit, you (or the aircraft operator) are responsible for checking with the CFMU that you will not pick up a slot for an earlier departure.

If your new expected EOBT is more than 15 minutes before your filed one (such as Bookworms example above), then you have 2 options.

You are in luck if the time is 30 minutes or less from your CTOT and your revised CTOT is no more than 30 minutes different from your original ... and you are in contact with ATC at your departure airfield in the UK. UK aerodrome ATC can then contact CFMU on your behalf to arrange a new CTOT. If there is no ATC unit at the aerodrome, then you are responsibile for contacting the CFMU to arrange the early departure, which they will try and facilitate if they can.

For anything else over 15 minutes, you will have to file a CNL message, followed by a new FPL at least 5 minutes later. Then see the above once more
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Old 27th May 2008, 20:15
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The lead time parameters are there for many reasons.

If one PPL decides to ignore the requirements then perhaps no big problem - hey what is an extra C172 on the sector loading chart.

However, if one does it then many will do it and hence traffic load planning and many other aspects which rely on the FPL being in the system some time before the departure / join is requested disappear out the window.

There are reasons for the limits specified.

Comply with them until you can convince those in authority that they can be changed can be the only practical response.

The only people who have to file very short notice flight plans are state flights and they are exempt from the requirements.

PPLs heading off on some IFR jaunt have no excuse for not filing their plan in good time.

Regards,

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Old 28th May 2008, 17:47
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The IFPS rules are clear that a minimum of 60 minutes are required for receipt of the IFR FPL before your EOBT.
Actually, I don't think that's the case. IFPS Users Manual says (section 3(2))

Flight plans shall be submitted to the IFPS for processing at least three hours before the
EOBT where possible. The IFPS shall also accept for processing those messages that are,
for operational reasons, filed less than three hours before the EOBT of that flight.


There's no mention of 60 minutes anywhere I can find.

The ATFCM Users Manual sets out procedures involving cancelling and refiling which are clearly designed to be used much closer than 3 hours before departure. For example

Any changes of more than 15 minutes to the EOBT of a filed flight plan shall be
communicated to the IFPS. The IFPS shall not accept negative delays: should the EOBT of
a flight need to be changed to an earlier time, that flight must be cancelled and re-filed with the earlier EOBT.
Note: Although it is not a requirement to update the EOBT of a non-ATFM-regulated flight
where the change is not more than 15 minutes, it is recommended to make such
an update to the flight plan held by the IFPS.


It seems highly unlikely that minor changes to EOBT are going to be anticipated more than 3 hours before the filed EOBT, so it appears the IFPS is actually encouraging pilots to cancel and refile and relatively short notice, even for minor changes. The CFMU even flags such flights as Late Filers or Late Updaters. A good 10-20% of flights fall into that category.

Clearly, it's undesirable to have lots of short term changes, and where it's operationally possible, which is most of the time, an initial FPL can be filed considerably more than 3 hours in advance. But there are many changes that are only operationally practical close to EOBT (bringing forward the flight is one possibility already mentioned, rerouting or a change of RFL because of weather is another example). These seem to be handled quite seamlessly by CFMU, so it's not really the capability of the IFPS/CFMU that I'm concerned about.

So when you write

The problem will be if you are one of the rare flights whose details have not made it in to the ATC system in time for your call,
what I'm trying to get at is more clarity as to how long "making it into the system" takes in practice, so that I can avoid any need to impose upon your or your colleagues' goodwill to handle a non-standard situation.

I'm only interested in IFR airways flights, so the "bureaucratic problems" associated with crossing FIR boundaries probably aren't relevant, even though the point is a good one for an uncontrolled flight.
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Old 28th May 2008, 20:15
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I'll try and dig out a sample flight at work tomorrow and see how long between IFPS pushing it out and it being available in the UK FDP system.
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Old 28th May 2008, 20:52
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The 60 minute requirement is an ICAO Annex 2 (Rules of the Air) requirement and applies to flights that will be provided with an ATC or advisory service.

The 3 hour requirement for flight plan submission in the case of flights which may be affected by a flow regulation is also an ICAO requirement contained in the European Regional Supplementary Procedures - DOC 7030

All the CFMU do is simply remind pilots that when reading the DOC7030, they should basically take the "may" to mean all IFR flights.

It must also be remembered that while in some cases making changes to a current flight plan my require a DLA message and (after getting an ACK) a new FPL message be sent - eg change of EOBT to an earlier time - tis is currently the only method by which this can be done and it still falls within the overall issue of making a change to a flight plan in the system rather than filing a totally new flight plan where none has existed before at the last minute.

So overall the message must be that the time it takes to get round the system makes no difference be it 3 seconds, 3 minutes or 3 hours. The requirements are that the FPL is filed at least 3 hours in advance IFR and 60 minutes in advance VFR when an ATC or advisory service is required.

When a smaller timeframe can be used then the ICAO DOC 7030-EUR will be modified.

Regards,

DFC

Last edited by DFC; 28th May 2008 at 22:05.
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Old 28th May 2008, 21:23
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I'll try and dig out a sample flight at work tomorrow and see how long between IFPS pushing it out and it being available in the UK FDP system.
Thanks PPRuNe Radar, that would be a very interesting datum.
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Old 3rd Jun 2008, 13:35
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Been off flying for a few days, but when I checked, the UK National Airspace System was receiving plans from IFPS and automatically inputting them in to the NAS Flight Data Processing system within 2 minutes of the time the plans were showing as being filed with IFPS. This system feeds data to all the UK Area Control Centres and many of the large airfields. These were plans with no errors or things which the UK NAS system didn't like.

For plans which requires some manual intervention in the UK NAS system, they join a queue, so their turnaround time will depend on how many other plans are ahead in the queue for correction. This number is usually quite low, less than 10% of all plans submitted in to the UK NAS system if I recall.
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Old 3rd Jun 2008, 17:26
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Thanks for that, PPrune Radar.

These were plans with no errors or things which the UK NAS system didn't like.

For plans which requires some manual intervention in the UK NAS system, they join a queue, so their turnaround time will depend on how many other plans are ahead in the queue for correction.
So are there plans that are accepted by IFPS (and therefore compliant with airway structure and RAD) but still unacceptable to the UK NAS system and therefore requiring manual intervention? What sort of problems might there be with the FPL that require manual intervention at that point?
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Old 8th Jun 2008, 21:15
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I'll have to check but I understand it is for problems such as plans which go through active Danger Areas (on CDRs) since IFPS is not 100% foolproof with rejecting these. I am sure there are other examples as well and I'll post them when I find out.
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Old 10th Jun 2008, 11:17
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After checking with some of the experts, examples where manual inputting will be required are:

flights on routes which go through active Danger Areas,

flights which are being rerouted on to tactical CDRs when a Danger Area has been cancelled earlier than scheduled,

flights which are on infrequent routes which have not been 'adapted' in the Flight Data software (if the plan is accepted as filed, the controllers will get all sorts of wierd and wonderful strips from the system since it is using direct route processing and not a controlled adaptation),

flights which have filed point to point routes in the Upper Air Space (this is not allowed in UK AIP, but IFPS will still accept them if the maximum distance between DCT waypoints is not exceeded),

non standard flights,

etc.

This is not an exhaustive list and some of the problems most definitely lie with the UK Flight Data Processing system, however, the contingency for this is the minimum filing time which is supposed to be followed

There are obviously a few disconnects between what IFPS can accept and what the UK actually wants. Some are being addressed with fixes (Danger Area and CDR conflictions for example) and some are probably in the too difficult bucket given the UKs differing types of airspace (DCT route problems in certain classes of airspace).
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Old 10th Jun 2008, 11:42
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Thank you, PPRuNe Radar. That's both interesting and practically useful info.

Is the change (where one is required) dealt with by issuing a different clearance to the aircraft in question (either on the ground or crossing teh FIR boundary), or is the clearance left as originally filed with IFPS?
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Old 3rd Sep 2010, 00:22
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Take off early

Dear Sirs
I'm an atco in Mongolia
I'd like to find out icao docs related in early take off permission.
It's been working some years ago in here. Nowadays we have changed our regulations. Unfortunetly there aren't anything about that. The big boys don't accept such cases and even they constrained us to follow eobt on daily schedule.
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