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Guest tompeel

PMDG 747-400 takeoff de-rated thrust

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Guest tompeel

I came across some documentation for the B767 from LevelD about specifying a de-rated thrust limit by inputting an assumed temp. The documentation is a set of tables listing V-speeds and assumed temps for various runway lengths, flap settings and takeoff weights. Is there anything comparable for the PMDG747? The manual mentions the assumed air temperature on the FMC, but not how to use it for de-rated takeoffs.Tom

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Guest tompeel

Yes, I'd heard of this, I was interested in trying to find some tables or quickref charts tables- you know, like the fuel planning ones in the PMDG 747 manual, which I do actually use.T.

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Guest poschrob

Nowadays, most operators also use software to determine the correct flap setting, derate temps etc.Furthermore, those tables differ from airport to airport (runway to runway, rwy condition to rwy condition etc), so you'll never get or find one.TOPCAT is just the most accurate and realistic tool one can find for these purposes. It is developed by a rw pilot.Rob

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A lot of aircraft have laptops on board with software to do the calculations for you. I had a chance to look at one and was very surprised to see it looks almost exactly like TOPCAT.I had always thought the design and layout they where using was made up for us Sim guys.I remember reading a accident report about a classic 747 Freighter that crashed in Africa due to the crew using the previous sectors derates from the software so always a good idea to make sure you are feeding it the correct data!Rob


Rob Prest

 

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Guest tompeel

Rob by chance yesterday I came across an accident report of a crash at Halifax NS where the analysis was that the crew mistakenly used T/O data from the previous flight that was still stored on the laptop, and had failed to crosscheck with a manual calculation. So, I'd still like a quickref chart(!).T.

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Guest poschrob

Again, those are not available.A quickref chart wouldn't help you as there are just too many variables one has to take into account when calculating the t/o performance. If you have a chance watch the ITVV B747 video where the F/O explains how it's done. Believe me, it's a lengthy procedure for which you need charts and tables which are not available for us.Topcat is your friend.Rob

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>So, I'd still like a quickref chart(!).There is no single chart but rather chartS - even separate charts for different runways at the same airport prepared for different airlines (which may have different engines). This is necessary because everything here counts - runway slope, terrain/obstacles at the end of the runway, etc. These are examples how they look like for some of the airports/runways:http://ops.precisionmanuals.com/wiki/Assum...take-off_chartsMichael J.http://img142.imageshack.us/img142/9320/apollo17vf7.jpg


Michael J.

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