IO540
IOW, they cannot find or won't look for it, so the end result is still that you are summarily stuffed.
I've checked with our even more experienced experts and here's what they tell me. All IFR plans will be received at the Area Control Centre (ACC) and are stored in both hard copy (on a printed back roll for backup purposes) and electronically within the Flight Plan Reception Suite Automation (FPRSA) computer system. If the flight plan is one which any of the UK ACC's have an interest in (i.e. flying on Airways or TMA's, or flying outside Controlled Airspace where a service is provided - usually on the handful of Advisory Routes, or in airspace where Scottish provide ATSOCAS), then the plan is automatically input in to the National Airspace System (NAS) Flight Data Processing (FDP) computer - or, if it has errors or things NAS does not like, then it is referred to a human for amendment. If the plan is IFR, but not of interest to a UK ACC, then the plan will still be within the FPRSA system, but will not be populated in the NAS FDP. It will be a very rare occasion where they can't find a plan and do something with it, the more likely thing to prevent a plan being 'elevated' is one of ATC staff being too busy to spend the time doing so. It's just down to circumstance at the time.
The Flow Management guys at each ACC can also access the IFPS database and pull up plans which have been filed in the system, so there is another alternative for sector staff if they can't find anything in the FPRSA kit.
IOW, if you file IFR OCAS, the end result is that you have wasted your time because Eurocontrol will, I assume, not be interested in Class G.
IFPS will process any plan flying through airspace where the environment has been specified by the ATC authority of the State, including any routes or segments they are not interested in. Eurocontrol only operate the system on behalf of the Eurocontrol member States, and have no say on what these States can and cannot receive. The State will specify what they wish to receive in the airspace environment details they provide to Eurocontrol. In the UK, IFR plans for flights outside CAS will be received reagardless of route or airspace type and are then processed accordingly.
As I said, at Scottish ACC all IFR plans outside of CAS will be automatically processed and will sit in the NAS FDP as 'proposed' plans. This is because they provide a service under ATSOCAS in their FIR, as well as in areas of the London FIR over the North Sea and the Irish Sea. Manchester also have a more limited service provision outside CAS and will process plans appropriate to the service they provide (their FPRSA is carried out at the Scottish ACC in any case). London ACC and Terminal Control are at the other extreme and don't generally carry out ATSOCAS, so probably just leave the plans in FPRSA and don't input them in to NAS FDP, hence your problems you have outlined.
OK, so the code is not generated by Eurocontrol but is generated when requested by somebody. AIUI, this still means that if the departure tower gives you a squawk which is different from what would have been generated, your flight does not get matched to the filed flight plan.
Eurocontrol provides only 2 services when it receives a flight plan. It distributes it (through IFPS) and it provides a Central Flow Management Unit service (Flow Control).
I think you are getting too hung up on the squawk and its relationship with the Flight Plan. In the UK NAS system, flight plans have 2 states. They are either dormant and awaiting activation (the state is called 'proposed'), or they have been 'activated' and the FDP computer will be processing them and passing updated data along the flights route on elapsed times, flight levels, co-ordinations, etc. There are 3 ways a flight can be activated, only one of which involves the squawk.
Firstly, a flight can be manually notified as airborne or passing a waypoint and then activated by the sector staff within the system using an appropriate message code. This is the method used (generally) outwith the London TMA airfields and Manchester TMA. Note that it doesn't matter what squawk the flight is wearing at the time of activation, nor does it have to be talking to the ACC. The flight has been manually activated and the initial processing will be carried out using system elapsed times based on the filed TAS and the winds held in the system. Once the aircraft is in contact with the ACC (or it could be before if the squawk is passed to another agency) and begins squawking the NAS FDP assigned squawk, then other radar data processing begins and is used to update the NAS FDP with more accurate data on the flights progress, amending ETAs, etc, as the flight is tracked along its route.
Secondly, a flight can be activated by receipt of an electronic data transfer message (known as Co-ordination Point [COP] estimate) from an adjacent ACC. The NAS FDP now processes the flight exactly as in the first case.
Lastly, the flight might depart from an airfield which has 'Auto Departure Message' status, whereby the radar picks up the expected squawk in the expected place (within a certain distance from the departure airfield) and within a parameter window of the expected ETD, and then automatically activates the flight within the FDP. The flight is now processed and uses radar updates as per the end state of the examples above. As these airfields are all within CAS, it is not really a relevant method of activation for IFR flights commencing in, or wholly operating within Class G airspace.
My "amateur" comment was mostly tongue in cheek; I am an "amateur" too But it is not wholly tongue in cheek because ATC are only human and despite their professionalism (which one must say is higher in some countries than in others) they have human attitudes too. The way a pilot goes about things does affect the kind of service he gets (again, more in some countries than others) and this is why I like to find out how the system works.
I agree.
I did actually file an IFR FP OCAS (via AFPEx) some time ago and due to bad weather spent about an hour trying to get it elevated to airways (so I could climb to VMC) and got politely fobbed off at every step. This is why I think filing IFR FPs OCAS is a waste of time.
AFPEx will (I presume .. never having had to do one) cope with the submission of a Change message (CHG), but that assumes you had it available. NATS also publishes the contact details for their FPRSA positions, so a call to them can often get your change input quickly if needed.
Regards
PR
PS My experts also tell me that if a flight is not activated in the NAS FDP at the expected ETD, then the flight drops its SSR assignment after a few hours (another can be requested manually if the flight subsequently appears), and drops the plan out of NAS after 5 hours. Other countries ATC units may drop it much quicker of course !!