During my training in the US we were filing shortly before the flight. It could have been as short as 5 minutes.
Now I just read the German NfL I 168 / 12, dated 12 JUL 2012, and it says one should file at least 60 minutes prior to EBOT.
What is recommended practice?
File way ahead of time (eg. the day before the flight) and then, if needed, send in change or delay requests?
Or
Arrive at the airport, brief the weather and then file before prepping the aircraft? The lead time might be as little as 15 minutes or even less.
So far I have used the DFS AIS web portal. The one time I was trying Rocket Route the flight plan had not been received by DFS Langen and the lead time was probably around 30 minutes.
RocketRoute sends the flight plan directly to the Eurocontrol AFTN addresses (actually it is even more direct than that, it is transmitted to a Eurocontrol server). DFS AIS does the same but it appears that every flight plan is first looked at by German AIS. That’s a luxury service no longer available in most other countries.
Usually it is fine to file and then start up immediately. However, in case your flight plan is not what the ANSP expects, it goes to a manual correction workstation and might not be available immediately. There is no way to know whether the flight plan goes directly to the ATC screen or first to the correction desk.
I have never had an issue with filing on short notice. Filing 60 minutes before sounds like a good idea but in case that is not possible, less time than that works as well.
You will get different answers 
If you file to Eurocontrol (i.e. “I”) the route is distributed to the countries in question at a time EOBT minus X (where X is chosen by each country that uses Eurocontrol, but is of the order of 600 minutes).
So if you file 4 days before EOBT, nobody outside Eurocontrol will see the FP until EOBT minus X.
If you file at EOBT minus 5 minutes, the FP (if validated, obviously) will be distributed within seconds (but see note below). If you then call up the departure tower and they say they’ve got it (which they should have) you can fly. I have done this a number of times, and it works on a Greek island just as it works at Shoreham. Sometimes this has to be done because somebody (me) has screwed up and filed the FP for the wrong date, etc. and this is discovered only when one is about to taxi out.
That’s the practical answer
One problem with leaving it till late is that Eurocontrol allocate any slots (CTOTs) in order of when people filed, done so that a later means that if slots are being generated, you are more likely to get one. There is a complicated system behind this, designed to frustrate airlines who would play the system in various ways e.g. to break the slots by cancelling a FP (which attracted a slot) and filing another one just before EOBT and hoping to get out of there before the tower gets a chance to tell them they have a slot. My vague recollection is that slots are allocated commencing at EOBT minus 180 minutes, which is why one is ritually told to file at least 3 hours before the flight.
The advantage in filing days early is that
and then there is one less thing to doObviously, my comment about “distributed within seconds” is true only if the filing agency actually transmits it to Eurocontrol promptly (via the AFTN or via the Eurocontrol B2B interface). I have no idea how fast RR is, especially when it is busy. Or it might have downtime. In recent years I have always used EuroFPL or AFPEX, and AFPEX especially is absolutely instant.
However, in case your flight plan is not what the ANSP expects, it goes to a manual correction workstation and might not be available immediately.
How would that square up with the principle that, outside the UK supposedly, a validated IFR FP can be flown as filed?
How would that square up with the principle that, outside the UK supposedly, a validated IFR FP can be flown as filed?
This applies only to flight plans that are not validated! In Germany, you usually file your flight plan with DFS and they pass it on to Eurocontrol for validation. If Eurocontrol doesn’t validate it as you filed it, DFS will modify it for you until Eurocontrol is happy (and you as well).
That’s an amazing service, in this modern age of, ahem, the internet
Any bets before they shut it down?
This applies only to flight plans that are not validated! In Germany, you usually file your flight plan with DFS and they pass it on to Eurocontrol for validation. If Eurocontrol doesn’t validate it as you filed it, DFS will modify it for you until Eurocontrol is happy (and you as well).
That’s actually not correct. All flight plans that DFS receive from Eurocontrol are looked at and might be sent to a correction desk at the center. This is located directly with the ATCOs. You can have valid IFPS flight plans that still violate some unpublished DFS rules. We’ve had this case recently with autorouter and I’ve discussed the topic at length with DFS staff.
That’s an amazing service, in this modern age of, ahem, the internet
The same exists at Eurocontrol. If I file an I flight plan say “EGKA to Peter’s grandmother’s house” the flight plan will not be rejected but sent to the manual correction queue at Eurocontrol. If more than 2% of the flight plans filed through a Eurocontrol partner go to that queue, the partner will have an unpleasant conversation with his Eurocontrol liaison.
You can see this with AFPEX where if you file a weird one and put RMK/IFPS REROUTE ACCEPTED (not sure if this is required) it will tend to come back ACK if you get lucky, or will go MAN for correction.
If I file an I flight plan say “EGKA to Peter’s grandmother’s house” the flight plan will not be rejected but sent to the manual correction queue at Eurocontrol.
They won’t touch it unless you have put RMK/IFPS REROUTE ACCEPTED on it.
And then they will fix it only if the fix is small, so filing EGKA DCT LGST won’t be corrected I am 99% sure they will not do any total route generation (even if it would be trivial, with their tools).
You can have valid IFPS flight plans that still violate some unpublished DFS rules
You mean… like most of the UK
In Germany? Impossible!
You can see this with AFPEX where if you file a weird one and put RMK/IFPS REROUTE ACCEPTED (not sure if this is required) it will tend to come back ACK if you get lucky, or will go MAN for correction.
I thought every FP filing service behaved like that… But then I have filed only prevalidated FPs in the last few years, not least because I want to know up front what route is being filed and don’t want to discover it at the last minute, by plotting the MAN (manually corrected) message on the map.
…not least because I want to know up front what route is being filed and don’t want to discover it at the last minute…
As a pilot, one needs to be flexible Quite frequently, after calling for startup, we will get the answer: “callsign421, information X correct, startup approved, however we have a modification of your route – are you ready to copy?” That modification sometimes affects the whole flight, different departure route, different routing thereafter, different flight level. Last time I had this was in France: we had filed and acknowledged a northbound routing via Paris and Frankfurt, what we got was soutbound via Lyon and Strassbourg. Not one point on our PLOG corresponded to that routing. Flight time? Fuel? Enroute weather? Insha’Allah …
Peter perhaps it is so, but a company software I use at work sometimes doesn’t relay any messages back other than slots, rejections and acknowledgments so I don’t see MAN there.
Our ops team at work often file a flight plan with AFPEX and just put DCT in with a reroute accepted to find validating routes. If they reject it and don’t reroute it they just keep sending it until they do. State of the art stuff with our lot.
