Flight Plan Differences [Archive]

bookworm

17th Feb 2008, 14:55

Is there some fundamental problem here or are these just a series of one-off events?

Nothing that a major Eurocontrol initiative (http://www.cfmu.eurocontrol.int/cfmu/gallery/content/public/presentations/docs/uf_05_2004_fly_single_fpl.pdf) can't eventually fix.

I've certainly had issues that fit the description you give, omega. In my case, it was usually a routing via CLN SASKI COA which complies with the RAD and is accepted by CFMU, but seems to confuse both London and Brussels whose systems indicate a DVR KOK routing. To their credit, both were extremely helpful after the event in assisting to try to find the underlying problem, though I'm not sure if anything is resolved. There seems to be an occasionally variance between the RAD and letters of agreement between centres.

but I have often wondered how crews get to know about these changes

Typically, it's when ATC gives a clearance direct to a fix that's a long way off your route in the tone of voice that implies they think they're doing you a favour... ;)

flowman

17th Feb 2008, 20:56

The FPL route in the cockpit and the FPL acknowledged by IFPU should be the same.
That's not to say that ATC cannot issue a clearance along a slightly different route for their own reasons.
There is not enough info from the above posts to give a definitive answer but if you can supply the following info:
Date of Flight, c/s and city pair
I can try to get an explanation.
flowman

Bigears

17th Feb 2008, 20:57

Does your Ops put 'IFPS Re-route accepted' in the FPL?
This is one possible reason why it has been ACK'ed but turns out to be different (as Spitoon has alluded to).

Another reason: If a FPL has been 'referred for manual intervention' (i.e. UK computer says 'no') the route or level may have to be altered, but should always be accompanied by a note on the strip to say what has been filed.

1985

18th Feb 2008, 06:54

In my case, it was usually a routing via CLN SASKI COA which complies with the RAD and is accepted by CFMU, but seems to confuse both London and Brussels whose systems indicate a DVR KOK routing

CLN - SASKI - COA is not available FL100+, its a one way airway. CFMU should know this if they don't then something needs to be done.

bookworm

18th Feb 2008, 07:54

1985

Yes, and it is available below (actually up to FL110), which is what London and Brussels didn't seem to know.

EBBU

18th Feb 2008, 07:56

I feel it happens regularly that the route that is accepted by CFMU is not allowed in the Letter of Agreement between the ATC units concerned. Let's hope this will be a disappearing problem...

And just a bit more on the SASKI - COA routeing.
Straight out of the Letter of Agreement between LTC and Brussels ACC :

Flights from LTC to EBBU on L179 (SASKI - COA):

Flights with destination EBOS, EBBR TMA(EBBR, EBMB, EBAW, EBCV) and EBCI may be accepted via L179. FL170 will be the maximum level. An approval request is required for traffic above FL115.

Even though the use of L179 is limited to the flights with the specified destinations, we get a lot of approval requests for overflights too...

DFC

18th Feb 2008, 08:29

There is a requirment for the flight plan to be included with the paperwork for the flight. We also include the ack message also so that pilots know the flight plan as shown is accepted.

When we get the weather and notams briefing (much closer to EOBT than the filing time), we ask for a printout of the CFMU route points which will include any re-routing by flow.

The problem is that when an ACC for local reasons change the routing they do not let the CFMU know and consequently you get a route different from what you were expecting.

We checked this out and the decision for the time being is that;

a) The filed flight plan is not being amended by the ACC and thus in the radio failure senario (prior to the new clearance) you go as filed.........(even if filed and ACK'd at FL100 via LAM). The ACC are aware of this and note it on the strip for the controller. They will not have a problem.

b) Route changes are treated like any directs or shortcuts enroute and very few make a significant effect on the fuel burn - at least not one that is outside the natural contingency.

c) Where regularly pilots find that the filed route and the actual route clearance are diffeent they include such info on the voyage report and the goold old ATC liasion person :) checks with ACC, CFMU etc to see if it is better to file a new route.

Regards,

DFC

omega

18th Feb 2008, 09:36

Flowman
A recent example to hand is EGSC to EGPN 11 Jan 08 c/s MCE10A. It became apparant that ATC were using a different hymn sheet when we were transferred to Scottish (round about POL, I think) and weren't able to make contact for a short while due to R/T congestion. Continuing with our acknowledged FPL route in the meantime was obviously a surprise to Scottish who subsequently read out a completely different route from the one we had.
As someone else noted, it would probably only become a problem in the event of R/T failure - giving ATC more difficulty in predicting the route we were likely to follow.
On a similar topic - it quite often seems impossible to get a FPL accepted by CFMU for a route which is known to be used by ATC (eg northbound across France to GUBAR or AKIKI) and which one eventually ends up following anyway.
Any ideas why that might be so?

PPRuNe Radar

18th Feb 2008, 10:49

A recent example to hand is EGSC to EGPN 11 Jan 08 c/s MCE10A. It became apparant that ATC were using a different hymn sheet when we were transferred to Scottish (round about POL, I think) and weren't able to make contact for a short while due to R/T congestion.

The Flight Plan indicates routing via POL SHAPP TLA GRICE PTH then leaving CAS DCT EGPN. There is no Standard Route between EGSC and EGPN.

At the time of the flight, EGPN arrivals were treated as EGPH inbounds by Scottish and transferred to Edinburgh Radar either on a heading towards their inbound fix (TARTN) or on the pilot's own navigation direct to TARTN, EDN, or EGPN.

The benefits of this tactical rerouting are to ensure the aircraft enters less sectors (freeing up capacity), with the spin off of a more direct routing to EGPN for the pilot.

This procedure has now changed and Edinburgh no longer work this traffic but it is handled internally by Scottish. You'll probably still get put on a direct track towards EGPN, but on a more efficient descent profile.

Of course that might not be what you have filed, and the longer route should still be available if you really want it :ok:

bookworm

18th Feb 2008, 12:05

I feel it happens regularly that the route that is accepted by CFMU is not allowed in the Letter of Agreement between the ATC units concerned. Let's hope this will be a disappearing problem...

Surely then it's up to the ATC units to get the RAD appropriately amended?

Regarding SASKI-COA, the LoA you quote doesn't make the situation below FL115 explicit. L179 is a normal airway with no RAD restrictions in that direction. There is no RAD restriction on destination. The Brussels supervisor (was it you?) with whom I spoke last time quoted the LoA (and informally suggested that you tend to accept anything London sends your way anyway) but there doesn't seem to have been any move towards consistency between LoA and RAD.

If the problem disappears, I'd be grateful if it disappeared in the direction of the LoA being made consistent with the current RAD (i.e. all flights permitted below FL115). ;)

bookworm

18th Feb 2008, 12:14

When we get the weather and notams briefing (much closer to EOBT than the filing time), we ask for a printout of the CFMU route points which will include any re-routing by flow.
...
a) The filed flight plan is not being amended by the ACC and thus in the radio failure senario (prior to the new clearance) you go as filed.........(even if filed and ACK'd at FL100 via LAM).

DFC, are the instructions to fly the route as filed, or the route as indicated on the CFMU point-by-point calculation?

flowman

18th Feb 2008, 13:09

Omega, I've just come off nights and will be back at work on Friday.
I will try to get some answers for you then and to some of the other issues mentioned here.
Pprune Radar seems to have covered the answer though.

omega

18th Feb 2008, 16:18

PPRuNe Radar/Flowman
Thank you for all that. Obviously, always happy to accept 'directs' when available.
I no longer have easy access to the paperwork for that flight but, from (somewhat ageing) memory, the ACK FPL went something like: DCT MAMUL UL613 HALIF UN590 MARGO UN601 TLA DCT EDN DCT. I was pretty sure we wouldn't be routed that way, particulary as the initial clearance was towards BKY(as usual). It seems as if someone in operational ATC system changes these from the CFMU version (often to a more practical routing) but the crew only find out about it by chance.
Another thought on this general subject - why can't the CFMU website, which we use for checking out FPL's before filing, be programmed to advise what is possible rather than just saying what can't? I and many others, i'm sure, waste lots of time trying to iron out the bugs in a proposed route (incidentally, this is using a commercial flight planning system).

EBBU

18th Feb 2008, 17:47

@Bookworm

After some research, I don't think this SASKI - COA thing has a simple answer. I understand the reasoning of the Letter of Agreement between LTC and Brussels ACC (SASKI - COA is opposite to the departures from EBBR/EBMB and EBAW).
So, the LoA is not clear, the RAD says nothing and the Belgian AIP gives the restriction above FL115 only.
I'll have a talk with someone on wednesday, let's see what he says...

An additional problem might be that about 2/3 of the airway between SASKI and COA is in the Dutch FIR and is delegated to Brussels ACC.

Anyway, we are going a bit off topic here but if you want i'll PM you anything I can dig up.

OH, and no, I'm not a supervisor, just a regular ACC ATCO :)

flowman

23rd Feb 2008, 14:41

Omega,
My colleague in Flight Planning has done some investigation using the information you supplied and reports as follows:

-EGSC1600
-N0403F300 DCT DTY DCT STOAT UL613 TLA/N0404F290 DCT EDN DCT
-EGPN0100

This route was not accepted by the computer due to DCT LIMIT being exceeded on the segment DTY DCT STOAT .
As the FPL contained RMK/IFPS REROUTE ACCEPTED, the IFPS operator corrected the route to:
-N0403F300 DCT MAMUL UL613 FINDO UP600 PTH DCT
This is the final route that was accepted, that became valid both to FPS and FLOW, that was transmitted back to the FPL originator in the ACK and finally, that was also tramsmited to all ACCs concerned.
If the cockpit had anything else that would indicate a problem between the FPL filer and the cockpit crew.
In ACC: anything different from the route above is the result of changes performed by the ACC itself. ACC received from CFMU a route identical to the one in the ACK.

regards,
flowman

DFC

23rd Feb 2008, 20:27

Bookworm,

DFC, are the instructions to fly the route as filed, or the route as indicated on the CFMU point-by-point calculation?

Prior to flight we have to get a new printed flight log from ops which will include the new route and of course the new fuel figures.

Getting a new printout is far quicker than amending the old one and working out the new fuel requirements etc. :cool:

It also means that the FMS waypoints can be crosschecked with the PLOG.

---------

I think that the example of the Dundee inbound is a very good one;

The pilot wants to route one way

The IFPS system route him/her another way

The ACC then change the routing again because being in the upper air to findo does not work in terms of getting the aircraft down for Dundee and the IFPS does not take into account the availability of LARS from Leuchars whic is very handy some Dundee is non-radar.

Regards,

DFC

Itsonyatv

23rd Feb 2008, 22:53

PPRuNe Radar

23rd Feb 2008, 23:25

-EGSC1600
-N0403F300 DCT DTY DCT STOAT UL613 TLA/N0404F290 DCT EDN DCT
-EGPN0100

This route was not accepted by the computer due to DCT LIMIT being exceeded on the segment DTY DCT STOAT .

As the FPL contained RMK/IFPS REROUTE ACCEPTED, the IFPS operator corrected the route to:

-N0403F300 DCT MAMUL UL613 FINDO UP600 PTH DCT

As a further small point, I am not sure if IFPS can deal with it, but you are not permitted to file DCT routes in the UK UIR. The only exception is within the Scottish UIR, with prior approval either individually or for a routine operation.

As per the UK AIP ENR 1.1.1 :

4.3.3.3 Due to the routine operation of high speed military aircraft within the UIRs, civil aircraft operators should flight plan only on the published ATS Route Structure. When traffic conditions permit, ATC may authorize aircraft to fly more direct tracks.

4.3.3.3.1 For individual flights within the Scottish UIR, operators may file outside the published ATS Route Structure subject to authorisation by the Scottish ACC ATC Watch Manager (Tel: 01292-692763, Fax: 01292-692872). Authorisation for routine operations outside the published ATS Route Structure must be obtained from ATC Operational Support at Scottish ACC (Tel: 01292-692611, Fax: 01292-692610).

Obviously you can file DCT below FL245, but your plan would need to show the points where you are changing your FPL level between the UIR and the airspace below it.

flowman

24th Feb 2008, 04:25

Itsonyatv,
A small point, DCT limits are not set by IFPS, they are defined by the ATS providers of individual states. They make the rules, we apply them. This has led to some hostility from FPL filers in the past who do not understand why they cannot file the route they eventually end up flying.
Pprune radar supplies the reason for that in his (her?) post under 4.3.3.3 :ok:

bookworm

24th Feb 2008, 08:17

Bookworm has alluded to one of the problems that can arise when a flight plan contains point to point DCT routeings. Provided the distance between the two waypoints is within IFPS limits then a flight plan can be accepted that may not be on an acceptable route to a particular ATC centre. An amended route may be input at the centre - in the UK this should have a remark entered on the flight strips showing what had been filed by the operator.

I can understand that this might happen with some DCT routings. But it really shouldn't happen when the route filed is an ATS route! It's up to the states concerned to set out in the RAD what routes can and cannot be used.

As a further small point, I am not sure if IFPS can deal with it, but you are not permitted to file DCT routes in the UK UIR.

Well here's another inconsistency:

RADAN EG:
EGPX/TTFIR Below FL105 Max DCT = 100nms
EGPX/TTFIR FL105-FL245 Max DCT = 50nms
EGPX/TTUIR Max DCT = 30nms

Of course at UIR speeds, 30 nm doesn't get you very far. But if NATS doesn't want DCTs in the UIR, all they need to do is change the RAD entry.

This has led to some hostility from FPL filers in the past who do not understand why they cannot file the route they eventually end up flying.

It's perfectly reasonable that an aircraft gets to fly a route that cannot be filed. Just because ATC offers a direct shortcut 80% of the time doesn't mean that they can guarantee to do so 100% of the time. So the shorter route usually flown cannot be filed.

What creates difficulties is the reverse -- when a filed (and ACKed) route cannot be flown. That can cause issues with the fuel planning, and sometimes with weather planning where a filed route has been chosen to avoid weather.

I understand that flight planning is becoming more dynamic, and in future there will be more changes to ACKed FPLs shortly before flight. What's essential is that when the wheels leave the ground, the crew can be confident that the route they have in front of them can be flown to destination, even if a more favourable route might be offered in flight.

DFC, I'm sorry I didn't make my question clear, which is probably why you didn't really answer it. In the event of radio failure are your crews' instructions to fly the route as originally filed, or the route as indicated on the CFMU point-by-point calculation and now on the PLOG and in the FMS?

PPRuNe Radar

24th Feb 2008, 08:37

Of course at UIR speeds, 30 nm doesn't get you very far. But if NATS doesn't want DCTs in the UIR, all they need to do is change the RAD entry.

I agree from a systems point of view, that would provide the easy answer, since setting a DCT limit of 0NM would cause all FPLs with DCT in the UIR to be rejected.

However, that would also reject those FPLs where the DCT routeing had been agreed with the ACC in advance (e.g in the Scottish UIR), even although they are valid for that specific flight.

It would also possibly reject FPLs with DCT legs placed in the Lower Airspace portions of the flight, where the pilot had not specified level changes between the Upper and Lower Airspace.

You can't have your cake and eat it :p

Of course, if operators or pilots complied with the AIP in the first place in terms of allowable flight planning ........ :)

DFC

24th Feb 2008, 08:39

DFC, I'm sorry I didn't make my question clear, which is probably why you didn't really answer it. In the event of radio failure are your crews' instructions to fly the route as originally filed, or the route as indicated on the CFMU point-by-point calculation and now on the PLOG and in the FMS?

Sory for not making it clear.

If we are aware of the re-route pre-flight then we get the new flight plan with the new route and the new fuel requirements etc. Thus if during the flight we have a comm failure we will follow the route we have in the flight plan which will then of course match the IFPS route.

It may not match the route if it was changed locally at the ACC but as has been said, the ACC people make a note of the change and are thus aware that if a comms failure occurs our flight may not follow the route they have.

In the case of the UK, this posibility only exists until you call the first UK enroute sector because on initial call they issue a clearance which normally includes if not a point to point route and the STAR at least some points that will keep you going well into UK airspace.

Thus I hope that you can see that it is important for us to have the ATS Flight Plan (as amended) the PLOG and the FMS all in agreement before we depart.

In flight the only way we become aware of a re-route instigated by ATS is via a revised clearance. Of course we must assess the change in terms of fuel, etc etc but usually it is a shortcut and it is rare (but not unknown) that a more direct can cost more fuel.

Perhaps flowman can confirm this but as far as I am aware if IFPS change the flight plan then the revised flight plan is re-transmitted or is it just a change message I can't remember.

Regards,

DFC

bookworm

24th Feb 2008, 18:02

Of course, if operators or pilots complied with the AIP in the first place in terms of allowable flight planning

I'm sympathetic to that. But the reason we have the CFMU, IFPS, RADs and all that go with them is to make flight planning a joined up exercise over a continent made up of dozens of FIRs, some of which are the size of a pocket handkerchief. If every state puts exceptions and special cases in the AIP rather than playing along with CFMU, flight planning would regress to the dark ages when it took a visit to the AIS foreign library at LHR to plan a 2 hour flight. ;)

PPRuNe Radar

24th Feb 2008, 20:00

I agree :}

0NM DCT allowable in the UK UIRs seems the only way to catch all. It is then crystal clear that you will have to file via ATS routes in that airspace, otherwise your plan will be rejected.

It would however catch the odd approved DCT route flight out so I guess they'd be penalised, but I'm sure some workaround such as a phone call to the ATC Supervisor in Scotland once the plan has been filed would solve it. A manual input could then be put in to the UK FDP to allow the direct routeing without upsetting IFPS :ok:

Such a move in IFPS would also presumably catch out those who file DCT in airspace where they will be in the Lower Airspace but don't file their profiles correctly. Which might aid the education process for those who file the rejected plans, so maybe it's a good thing :\ :ok:

bookworm

25th Feb 2008, 07:14

It would however catch the odd approved DCT route flight out so I guess they'd be penalised, but I'm sure some workaround such as a phone call to the ATC Supervisor in Scotland once the plan has been filed would solve it.

It's also possible to list the approved DCT routes in the RAD. There are dozens there already -- take a look (http://www.cfmu.eurocontrol.int/cfmu/opsd/gallery/content/public/rad/docs/13mar/enroute-dct.pdf).

Such a move in IFPS would also presumably catch out those who file DCT in airspace where they will be in the Lower Airspace but don't file their profiles correctly.

Ah. Profile discrepancies. Now there's an issue that is up for discussion this very week...

PPRuNe Radar

25th Feb 2008, 07:21

It's also possible to list the approved DCT routes in the RAD. There are dozens there already -- take a look.

Of course, but it seems to me to be pointless doing so for the UK UIR, as the whole point is that a special dispensation must be obtained from the ATC authority beforehand. Put them in a document, even with the conditions of use spelled out in three foot letters, and you would still just end up with everyone filing them and then wondering why they are being routed way off flight planned track in 99% of cases. (Military activity usually). Which brings us nicely back to the original example :ok:

Actually I'm leaning more towards the specification of 0NM DCT in IFPS for the UK UIR with every post. ;) And reviewing the RAD entries since they don't meet the policy statement in the AIP :ok:

omega

26th Feb 2008, 11:19

Sorry for my delay in responding - have been on route for a few days.

Thank you all for sharing much useful information on this and associated topics. Nevertheless, i'm still slightly concerned that ATC and the crew can be working from almost totally different FPL's. In the case I quoted: CFMU/crew - DCT MAMUL etc and ATC -DCT BKY etc. I suspect that this actually happens quite a lot but is not necessarily apparant because, on the day, the route is flown as a series of radar headings/directs. It's only when there is a break in communication at a critical point, such as a frequency change to a busy sector when close to an enroute clearance limit, (as in my quoted instance )that it comes to light.