Despite being a PPRuNer for a good while, I still haven't learned how to quote properly. So forgive my home made version please.
2 Donkeys said:
"Where the field is a farm strip, you could telephone for some sort of clearance, but it is more common to take-off and use either London Information or a local LARS/Radar unit to negotiate your entry into controlled airspace."
This depends very much on which part of the country you fly from and which controlled airspace you want to enter.
I fly from Bourn, Cambs. There is generally no problem in entering the local Class D (Stansted or Luton) on an airborne flightplan. The problem comes in trying to get into the TMA.
The difficulty (as I understand it) is that, even having filed and activated an IFR flight plan, the TMA controllers will not have a flight progress strip come out of their computer for the flight and will be therefore unwilling to accept the flight. The Luton and Essex controllers rarely have the time to solve this little problem for you. (Bourn is about 7 miniutes from Class D and about 8-10 minutes from the usual Class A entry points). This time is not enough to call London Info to request and obtain a clearance without orbiting outside CAS for an uncertain time.
So, what about telephoning before take off? For one flight, as luck would have it with a TMA controller sitting in the right seat, he tried to get the flight progress strip out of the system and onto the Essex or Luton controllers' position by phone before we departed. He succeeded, but it took him two or three calls over about 15-20 minutes and I think his success was more due his intimate knowledge of the system and who to talk to than anything else. In other words, not a method open to the average pilot. Even then, the Luton controller was not expecting us.
That leaves the third alternative, telephoning a local ATC unit (not the uncontrolled departure field) before take off and asking them to prepare the ground for you, so you can get the clearance soon after becoming airborne. I don't believe you have any right to such a service and you are relying on their good offices and other workload and priorities not interfering.
I would say it's an unsatisfactory situation for all concerned, pilot and controllers.
AA.