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Adam Reed

Landing Altitude

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Hello Gents.Just a quick one here regarding the LAND ALT in the overhead.For example if im landing at runway 09 at EGGP, with reference to the chart below (NDB ILS DME RWY 09), What would go in the landing altitude?Charts:http://www.ead.euroc..._2009-06-04.pdfThanks in advance, Adam.


  Adam Reed

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I use Runway altitude + 50 feet.Touchdown zone altitude shown on USA plate.


Best Regards,

Vaughan Martell - KDTW

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81 so put 100 in the overhead


                                                     

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Ok thanks guys , The only thing confusing me is the AD Elevation or the THR Elevation. So it's the AD one you should use. which on this case is 81 so round up to 100.I flew into LEPA today and the Airport elevation was 27' and the Runway was 8'. Would i round this upto 50 ?


  Adam Reed

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Ok thanks guys , The only thing confusing me is the AD Elevation or the THR Elevation. So it's the AD one you should use. which on this case is 81 so round up to 100.I flew into LEPA today and the Airport elevation was 27' and the Runway was 8'. Would i round this upto 50 ?
Technically THR, but normally AD and THR elevations will not be THAT much different. :)

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I think and perhaps someone can confirm that AD is aerodrome altitude and THR is runway threshold. The AD i think will list the highest usable runway elevation for the airport. In liverpool RWY27 is higher at the threshold that RWY09.Anyhow I very rarely see a big difference between them and normally choose the AD over the THR though I believe THR would be the correct choice.RegardsP.S. Yes if LEPA shows 27' round up to 50


                                                     

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I think and perhaps someone can confirm that AD is aerodrome altitude and THR is runway threshold. The AD i think will list the highest usable runway elevation for the airport. In liverpool RWY27 is higher at the threshold that RWY09.Anyhow I very rarely see a big difference between them and normally choose the AD over the THR though I believe THR would be the correct choice.RegardsP.S. Yes if LEPA shows 27' round up to 50
Which is the same as TDZ on some charts. Correct?

Rick Hobbs

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The controller is designed so the aircraft lands slightly pressurised by aiming for a cabin altitude "slightly less" (according to the FCOM) than selected LAND ALT. So my assumption has been to round the field elevation down, so for Heathrow (80 ft) I select 50 ft. If you round up the LAND ALT the aircraft might land unpressurised. Rounding down ensures it will always be pressurised on landing. However, if "slightly less" is actually more than the 50 ft selection step then it wouldn't matter either way, in fact rounding up might then be a better choice.Any RW NG pilots here who know what the correct setting is?Kevin Hall


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The controller is designed so the aircraft lands slightly pressurised by aiming for a cabin altitude "slightly less" (according to the FCOM) than selected LAND ALT. So my assumption has been to round the field elevation down, so for Heathrow (80 ft) I select 50 ft. If you round up the LAND ALT the aircraft might land unpressurised. Rounding down ensures it will always be pressurised on landing. However, if "slightly less" is actually more than the 50 ft selection step then it wouldn't matter either way, in fact rounding up might then be a better choice.Any RW NG pilots here who know what the correct setting is?Kevin Hall
Why do you want the aircraft pressurized on landing?

Best Regards,

Vaughan Martell - KDTW

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The Pressure Controllers pressurize the plane to 200 ft below the runway elevation for takeoff and300 ft below the runway elevation for landing.So rounding it off to + or - 50 makes no difference to the pressurization system.Fred.


Frederic Steiner.

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Why do you want the aircraft pressurized on landing?
It's the way cabin pressure controllers are usually designed. If the cabin isn't pressurised it will not be controllable and will simply follow aircraft altitude, Less comfortable for the passengers. Also, it's best if the cabin is always at a positive differential pressure. Negative differential creates a compression force and is less structurally stable. The cabin is pressurised slightly when the throttles are opened for takeoff, and before landing pressurised to below field elevation until after touchdown, as Fred's post above describes. This way the cabin altitude is always below the aircraft altitude. There's a graph showing a typical cabin altitude profile in the FCOM, vol 2.Kevin Hall

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