To add to WJT's explanation of 'B' Conditions markings, they're defined within the Air Navigation Order Part 1 Para 3 and Schedule 3, the ANO being the law that governs flight in UK airspace. As such they are controlled by the CAA with further regulations within Section A of the British Civil Airworthiness Requirements.
As Bill says, they allow test flights of prototype, new production, or modified (foreign-registered) aircraft where there is either no Type Certificate yet or there is not a valid Certificate of Airworthiness (there are various subtleties to this that I won't go into here!). A company needs an approval from the CAA to be able to carry out B Conditions flights and as part of this are allocated a B conditions registration number. Here at Cranfield we have G-36 which in my time here we've only used twice, doing test flights to support major mods on foreign-reg biz jets. If you're modifying a G-reg aircraft, there's no need to apply the B Conditions code.
Since EASA came into being things have changed a bit as test flights are done under an EASA Permit to Fly for applicable aircraft (for which I could write a long and very boring article on the difference between EASA and non-EASA aircraft), not B Conditions, and so the codes are seen less than they used to be.
If you're interested in B Conditions codes, current approved companies are listed on the CAA website within a list of BCAR A8-approved companies.
There are currently 13 companies approved for B condition operations ...to see the complete list of all including the current situation look at my site
IIRC the reason for such as the Harrier G-VTOL being given with full UK registration was that some countries would not accept demonstrators flying with military marks and Class B are only valid in UK airspace.
canberra;76224 wrote: As you say some countries are funny about military aircraft, not just demonstrators. There is a section at High Wycombe that deals solely with diplomatic clearances.
Well, looking at the hoops the Vulcan to the Sky chaps had to jump through to get CAA approval shows me that military aircraft have to satisfy, erm, different criteria. So I can see why some territories might be a bit sniffy about allowing them in.
There not beeing as you put it "sniffy" its all to do with diplomacy, quite rightly a government will want to know about having another countrys military in its country. And at MOD theres a section called "foreign liasion" who deal with requests from other nations to fly its aircraft in our airspace.
canberra;76251 wrote: There not beeing as you put it "sniffy" its all to do with diplomacy, quite rightly a government will want to know about having another countrys military in its country. And at MOD theres a section called "foreign liasion" who deal with requests from other nations to fly its aircraft in our airspace.
My point was that rules for military aircraft are (rightly) different to those for commercial or private aircraft, so I could see why a foreign nation would be wary of letting in an aircraft that could be held together with string and brown paper.
The aircraft serial system used in UK began in 1912. Army aircraft were serialled A1 onwards and Navy aircraft serialled N1 onwards. WW1 meant lots of aircraft built for the services and the Army soon got (1917 ish) to A9999 although Navy A/c were still using the N system when the RAF came into being, this series was then used for RAF aircraft ordered for use by the fleet and seaplanes. The army/RAF continued on using B ,C, excetera until they got to Z by this time serials had standardised on the format Z0001 to Z9999. running out of letters they then started again but with AA and three numbers AA001 to AA999. this series continues today. When the Navy N series ran out in the late 20's they started to use S prefixes (Seaplane?) but after this ended naval aircraft were numbered in the standard system.
Incidentally the N series was used twice, it was used again for RAF aircraft in the 20-30's
some letters were missed out, you will not find I or O letters as these could be mistaken for numbers.
canberra;76171 wrote: When I was on IV we had the last Harrier GR3 delievered fresh from Dunsfold and it was XZ999.
I was on IV at that time, we went on field deployment and the two jets in our hide on 4 site were XV738 and XZ999 I think the first and last production Harrier GR1/3 type. 738 was a sweetie and never failed, 999 was a friday afternoon jet, and a bit of a dog...!
canberra;76759 wrote: I was on IV at the time as well, small world isnt it? It wasnt either of those two that swallowed the telbrief cable was it?
No didnt swallow the telibrief, but I remember a rigger (Pee Wee?) when seeing out a Jet after a rainstorm he was up on the tail lifting the wet cam netting so it didnt snag on the fin, the pilot missed the stop signal from the marshaller,so he could get off, and the jet continued off on its way to the tin strip with a very worried looking chap on the tail. fortunately we stopped him before he got too far...!