December 27, 200421 yr At which altitude (15,000 ?) should I set a default air pressure value and what is that value (29.85 ?)Roger Roger See my specs in my profile
December 27, 200421 yr In the US it is 18,000 ft and the pressure is 29.92. I think other countries have a different altitude. ------------------------- Craig from KBUF
December 27, 200421 yr Thanks Craig.I needed this info to use with Flight Keeper.Roger Roger See my specs in my profile
December 27, 200421 yr A little more complete answer: The altitude you refer to is called the transition altitude, and a standard setting of 29.92 in or 1013 mb are set in the altimeter when climbing through that altitude. For descent, a transition level may also be specified by NOTAM/ATC which defines the flight level at which transition is made back to QNH/QFE, based on altimeter setting. If the altimeter setting is high enough, a flight level at/near the normal transition altitude can be near or at altitudes below Class A airspace (airspace above transition altitude is Class A airspace). For example, with an altimeter setting of 30.91 in, FL180 and 17,000 ft MSL are essentially the same altitude. In this case, transition level would be specified at FL 190 rather than the usual transition at FL 180.Any time you see an altimeter setting above about 30.40, any assignment to level at the transition flight level (i.e. FL180 in US) is probably worth a query to ATC.Transition altitude in US airspace is fixed at 18000 ft. In other regions it may be fixed, or it may vary by airport/region. In Germany, for example, it's fixed at 5000 ft as I recall.CheersBob ScottATP IMEL Gulfstream II-III-IV-V L-300Washington, DC Bob Scott | President and CEO, AVSIM Inc ATP Gulfstream II-III-IV-V Sys1 (MSFS20+24/XPlane12+11): AMD 9800X3D, water 2x240mm, MSI MPG X670E Carbon, 64GB GSkill 6000/30, nVidia RTX4090FE Alienware AW3821DW 38" 21:9 GSync, 2x4TB Crucial T705 PCIe5 + 2x2TB Samsung 990 SSD, EVGA 1000P2 PSU, 12.9" iPad Pro Thrustmaster TCA Boeing Yoke, TCA Airbus Sidestick, Twin TCA Airbus Throttle quads, PFC Cirrus Pedals, Coolermaster HAF932 case Sys2 (P3Dv5/v4): i9-13900KS, water 2x360mm, ASUS Z790 Hero, 32GB GSkill 7800MHz CAS36, ASUS RTX4090 Samsung 55" JS8500 4K TV@60Hz, 3x 2TB WD SN850X 1x 4TB Crucial P3 M.2 NVME SSD, EVGA 1600T2 PSU Fiber link to Yamaha RX-V467 Home Theater Receiver, Polk/Klipsch 6" bookshelf speakers, Polk 12" subwoofer, 12.9" iPad Pro PFC yoke/throttle quad/pedals with custom Hall sensor retrofit, Thermaltake View 71 case, Stream Deck XL button box Sys3 (DCS/P3Dv4/ATS/ETS): AMD 7800X3D, MSI MPG X870E Carbon, Noctua NH-D15S, 64GB GSkill 6000/30, EVGA RTX3090 Alienware AW3420DW 34" 21:9 GSync, Corsair HX1000i PSU, 4TB Crucial T705 PCIe5 + 2TB Samsung 970Evo Plus, TM TCA Officer Pack, Saitek combat pedals, TM Warthog, TM RS300 FF wheel/pedals, Coolermaster HAF XB case
December 28, 200421 yr Bob,This more complete explanation is great.Before I didn't care very much about these details. But now that I have discovered Flight Keeper and that I try to follow the rules to obtain the best scores in my flights, these informations are more important now.Thank youRoger Roger See my specs in my profile
December 28, 200421 yr BobJust to add a little.In Europe where our levels are lower it is normal practice to change to the designated pressure setting when a descent clearance and pressure setting is given.Hence, aircraft flying at say FL150 airways in Europe maybe told to descend to 2500 feet on 998. For this arguement the transition level may be say FL60 but having recieved and read back that clearance 998 would be used for the whole descent regardless of the transition level.Peter
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