November 21, 201510 yr If I were you, I believe I would forget about ever having any dedicated 300ER takeoff calculations that included de-rates and just use the method 77west has described in post #6 of this thread. Mickael, not to advertise, but TOPER already provides takeoff calculations for the 300ER including fixed derates and assumed temperatures. Romain Roux Avec l'avion, nous avons inventé la ligne droite. St Exupéry, Terre des hommes.
November 21, 201510 yr Author If I were you, I believe I would forget about ever having any dedicated 300ER takeoff calculations that included de-rates and just use the method 77west has described in post #6 of this thread. Yeh, bought Toper yesterday and I see it had quiet a lot of updates! So I use that for the 300-ER. Robert
November 23, 201510 yr The actual answer is pretty involved, but put simply: The FMC makes some assumptions, and does not take all factors into account. Additionally, the FMC also works forward. TOPCAT (and/or programs like it) essentially works backward. What I mean by this is that you cannot plan with the FMC. If you throw values in there, you're not going to get a full picture of whether those numbers will work or not. TOPCAT provides you with the ability to check the numbers to ensure the performance is okay on the runway, and in the climb. Moreover, TOPCAT offers the ability to take how much runway is available and de-rate/assumed temp your thrust in order to compromise engine life for runway used. In other words, if I have 10000' of runway, but I only need 5000' at full thrust, I can have TOPCAT work backward to find the de-rate/temp that would result in me using all 10000' in an accelerate-stop (engine out before V1) situation, which is essentially your "optimal" value for a de-rate/temp. The question you've asked is essentially: Why even have a fuel and route planner, when you have the FMC? Sure, you don't need either, because if you throw a route in the FMC, along with a few fuel assumptions, you can get an idea of how much fuel you'll need (see the NGX Tutorials for the fuel planning trick). The issue, though, is that the FMC doesn't have the ability to show you weather along that route, or wind ahead of time (so to see optimal times, you'd have to try an altitude, pull the wind, check the time en route, set another altitude, pull the wind, check the time en route), whereas a route planner usually has some functionality for those considerations. Cool, thanks for the heads-up! Cheers Balint Nagy
November 24, 201510 yr Hello all, Regarding the topic and particularly what you have mentioned Kyle, in my opinion, Boeing not allowing PMDG to publish the FPPM is also a matter of legal liability. In order to truly operate an aircraft you must do (or the dispatch office) the TO calculations with the FPPM or dedicated approved software. As mentioned before, the two biggest and most important questions cannot be answered with what PMDG provides with the software: Here is a field and atmospheric conditions; can I take off with the load I have, OR, how much load can I take and still be able to take off? If I can take off, how much can I derate in order to save the engines and still be safe Nobody can say that they trained with the sim and went out and failed with the real thing while it worked in the sim. In the sim - as provided - we don't have all that is necessary (legally) to fully operate like in reality hence no liability. Also, I think that it is part of the Boeing safety philosophy that a human conscientiously requests from and sets to the aircraft the TO performance and not allow some hidden computer in the avionics bay take these crucial safety decisions. However, the FPPMs were definitely used to produce the PMDG planes and they are true to the real thing as advertised. I was fortunate enough to have a real fppm and of course I jumped at the opportunity to test the performance at SLLP with one of the PMDG planes. It was just like the graph said (big smile on my face). Way to go PMDG! I am considering making a dedicated performance program for 777; does anybody know what would be the legal/commercial bounds in respect to PMDG and Boeing? Regards, Ionut (John) G. Micu
November 24, 201510 yr I am considering making a dedicated performance program for 777; does anybody know what would be the legal/commercial bounds in respect to PMDG and Boeing? As long as you don't make use of Boeing's and PMDG's proprietory data you can do want you llke. Gerry Howard
November 24, 201510 yr Commercial Member I am considering making a dedicated performance program for 777; does anybody know what would be the legal/commercial bounds in respect to PMDG and Boeing? Given the nature of the question, it would probably be safest to talk to any party you think has a stake in the idea. Kyle Rodgers
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