Hi, can anyone explain, in simple English please, the difference between TL and TA and the relevance of these two settings in an aircraft ?Thanks John:-wave Core2 Duo 66002048 MB DDR160GB HDDNVidia 7950 512mbSaitek Flight SystemHead TrackerRC4AShttp://fs2crew.com/linepilot.jpg

TL (TransitionLevel) is the flightlevel ABOVE, where one must use the STANDARD alt pressure setting 1013 hPa or 29.92 inHg.TA (TransitionAltitude)is the altitude AT OR BELOW where one must use the QNH pressure setting or the local altimeter pressure setting.Hope that is what you wanted to know :)

>TL (TransitionLevel) is the flightlevel ABOVE, where one must>use the STANDARD alt pressure setting 1013 hPa or 29.92 inHg.>>TA (TransitionAltitude)is the altitude AT OR BELOW where one>must use the QNH pressure setting or the local altimeter>pressure setting.>>Hope that is what you wanted to know :)>>>In that sense the sim might be a bit confusing. The altitude at which one transfers TO standard (TL on the way up) or FROM standard to local (TA on the way down) does not need to be the same.For that matter, its not always 18k either...

John, this subject is a bit tricky to explain in a few words depending on your previous knowledge about meteorology, ATC and such, so I

Yeah John best you do what Tord said, i dont know if the way i explained it to you is clear enough, don't know you prior knowledge.

Indeed it was clear enough. One can imagine it as a line. If you are closing on it from below it's called TL, if you are closing in from above it's TA.

Thanks for the replies. You have clarified it nicely for me !!JohnCore2 Duo 66002048 MB DDR160GB HDDNVidia 7950 512mbSaitek Flight SystemHead TrackerRC4AShttp://fs2crew.com/linepilot.jpg

Well, perhaps nitpicking from my side but it

Hi John,If you're using the default ATC in FS9 then be prepared for some compromises. FS9 (and now FSX) use a standard TA of 18000ft. Whilst this is the case for the area covered by the FAA it's completely wrong for the rest of the world.On the other hand Radar Contact does allow for different TAs. If you're serious about how your flights are controlled then click the link below for more info.End of shameless plug ;-)

No Tord, it is good you mentioned that...It is something which is regularly misunderstood...Andrew

To expand slightly on your reply, Transition Altitude (TA) is is the height above which Flight Levels are used. Yhe Transition Level is the lowest flight level allocated by ATC. It is chosen to maintain adequate vertical separation btween an aircraft flying at the Transition Altitude and one flying using the lowest flight level. It varies with barometric pressure.