Changing airspace and different TAs

[Dave Morgan 68]

Hello.What would happen in the real world if I flew at, say, 8000 feet from an area with TA = 18000 to another with TA = 3000.I did this (or noticed it) for the first time last night (France to UK) and maintained 8000 feet even when in the new airspace until I was ordered down to FL60. I received an 'Altimeter check' shortly before the new flight level (which may be a bit of a hint).I understand that if I was always under the TA I wouldn't alter the altimeter setting during changing weather conditions until given a new QNH but in the above case would I be expected to remain at 8000 feet until given a FL?Regards,D

[PeteP 2]

Now that's a question that's set my old grey matter whirling! Dave. It's so long since I designed the non-US altimetry system used by RC4 - at least 6 years ago, possibly longer - that I honestly can't remember what, if anything, I did about it. I clearly remember explaining to jd the possibility of that situation occurring and suggesting the phrase "adjust to FLxx" or "QNH xxx adjust to altitude x thousand ft" but I don't think we implemented it. I think the consensus was that the amount of work to be done on the program to deal with it was out of all proportion to the number of times it was likely to happen, so, the en-route phase was left 'as-is' and the 'problem' was dealt with, as you found, in the approach phase. Maybe jd can check the code but I think that's the situation.In the real world, it's much simpler to handle with the controllers involved issuing the appropriate pressure setting and initiating the level/altitude adjustment. You'll also find there's usually transition areas (or buffer zones) either side of a boundary where these changes take place. Simple to handle in real life - much more complicated in a computer program.Pete

[Dave Morgan 68]

Thank you, Pete.RC and RL aren't so very different then. The order just comes later in RC. I'm sure they're both easier to fly than to program! I'll just keep listening out for '...flight level...' or '...qnh...' depending on which way I'm going.Regards,D

[iainsmith 9]

Hello.What would happen in the real world if I flew at, say, 8000 feet from an area with TA = 18000 to another with TA = 3000.I did this (or noticed it) for the first time last night (France to UK) and maintained 8000 feet even when in the new airspace until I was ordered down to FL60. I received an 'Altimeter check' shortly before the new flight level (which may be a bit of a hint).I understand that if I was always under the TA I wouldn't alter the altimeter setting during changing weather conditions until given a new QNH but in the above case would I be expected to remain at 8000 feet until given a FL?Regards,D

France doesn't have a TA of 18000 does it? I've just been to Paris Orly and there it is 4000. Can't imagine it being 18000 anywhere in France.Iain Smith