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Guest DaveI

747 Fuel planning

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Hello All Is there a software Fuel Planner available for the 747 anywhere? This pencil and paper stuff is a bit tedious !CheersDavid

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Hi David,there are lots of fuel planners around - FSbuild etc - but I created my own tool with the help of excel. After approx 1000 hrs of testing I arrive within 1000 kgs at my destination - right now I am on the way from EDDT to CYYZ and my calculation called for 54N020W eta 1424Z and fuel at waypoint 69.3 ktons - actual was 1423 and fuel 69.7 .It was fun to build this tool and also flightplanning before the flight gives me fun and satisfaction and it takes only about 45 mins . . .BTW : the MD11 tool is ready to go . . .

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I have also developed a planner using Excel, look for either 744FuelPlannerV1-1.zip or 744FuelPlannerV1-1KG.zip (uses kilos) in the AVSIM 2004 Utilities library.

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Thanks Guys I just knew someone was ahead of me !!David

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Still though, I find PMDGs FMC to be the most accurate burn planner. One of our real world 744 drivers gave us an exceptionally detailed flight outline for a real world flight from London to LA. We (well, err, I) matched PMDG's burn modeling to that real world 744 flight. The burn from the real world flight and the burn the PMDG FMC projected was within a K or 2. Probably the simplest way is to load your flight plan and projected enroute winds, then let the FMC figure your burn (Hey, ya gotta do this anyway). This WiLL be your burn, sans winds mismatch (FS vs FMC's) and flight plan diversions (ATC, engine-out adventures, etc).Now add in all your extra, contingencies, taxi, etc and fuel 'er up. Launch on.I'm really interested to see how Active Sky is handling winds aloft in FSX. As it is now, there's no burn excitement. Without some kind of winds variability, what the FMC says will happen, will happen. BoArInG. Just like in real life. Ask a crew. Generally (and thankfully!) the most exciting part of the flight is walking through the terminal in uniform. AS needs a "Random Variability" button, something like PMDG's "Suprise ME" systems failure feature. Scribbling down a "fuel remaining / winds data" number on a crinkled flight plan would at last give you something to do every half or or so, just like a real crew.

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ActiveSky allows you to enter a probability number for winds aloft. I use a confidence factor of 80% such that the winds vary by 20%. You can increase that.

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I am on the way from EDDT to WSSS and will tell you the story about FMC fuel planning :waypoint / my calc / FMC calc / actual / diff mins calcBABIS / 120.1 /120.3 / 120.8 / -1RASPU /110.0 / 110.0 / 110.6 / +1TONSO / 102.3 / 101.5 / 102.6 / 0KEMOR / 85.9 / 83.4 / 86.2 / -1RIKAD / 76.0 / 73.5 / 77.2 / -1RK / 69.1 / 64.8 / 69.6 / 0PUKES / 59,9 / 54.9 / 60,7 / -1FMC readings were taken after level off at first alt FL310 So half way through fmc calc is about 5 tons off !! Based on other flights FMC will be off by 7 to 8 tons !! Karl-Heinz - EDDI/THF " Tempelhof "" The mother of all airports " - Sir Norman FosterEDIT : new waypoint added

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The FMC is simply encountering a different environment than it was initially programmed to expect. Let the fun begin. Write that VOR/DME circle in the ND and start keeping up with alternates. The real value of these flight planners is that it gives you a printed flight plan with fuel and time estimates at every waypoint. FSBuild will do this. Real crews scribble actual fuel remaining and winds at each WP and jot a + or - number by the fuel estimate. It's funny to watch this procedure fade-out about mid-trip with one-after-the-other "+.3" then "+.2" entries. It's about then you start to pick up "flight plan doodles." But this is the way crews stay ahead of an impending problem. Top of climb is too soon to be off by that much. Where did the discrepancy start and how did it develop? You were keeping good notes, right? (Just a rhetorical question. For your info only!)

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Hi Sam,we are talking about flight PLANNING . . .The PMDG 744-FMC is somewhat wrongly programmed - you cannot use it for planning purposes and it was never intended to be used as a planning tool - it should be used by the crew to follow the fuel management and compare it with the printed plan, which has always priority over the FMC !I know what I am talking about - my son is a pilot on the MD11 and we did several trips together - and all pilots I met followed the fuel flow very closly for the WHOLE trip, especially on a trip where alternate airports are rather rare like on a trip over the polar region ! And the real world MD11-FMC is as close to the planned fuelflow as possible . . . lets hope that the PMDG-MD11 FMC will be also so close . . . !On the PMDG 744-FMC there are some mistakes and a few months ago rsrandazzo himself answered a message from me that on future PMDG products they will have a close eye on FMC programming . . .The present FMC cannot be even used for fuel control :On the trip from BER to SIN, after TOC, the FMC indicated an ETA of 2011Z ( calulated was 2002 ) with 10.7 ktons of fuel remaining at destination - " insufficient fuel " message came up ! The forecast winds were entered already in the FMC, step climbs were calculated by the FMC and were followed exactly by me. The trip finished at 2003 (!!) and the fuel remaing was 20.3 which was 1.5 tons more what I calculated.As soon I climbed up one step the fuel at dest went up . . . why ? the FMC should have calculated it already - it "knows" the step climbs way before ! Same with the speed - it takes according to my feeling the PRESENT TAS to calculate the whole trip and NOT the TAS based on cost index, ISA and the programmed altitudes.Right now the actual temps are way above ISA, therefore the speeds are above normal and I think that forecasted temps will not be entered in the real world FMC's and/or in the PMDG-FMC so it can only be calculated as I said above . . . I use in my calculation the forecasted temps from ASv6.5 which are more or less accurate . . .Yes Sam, I keep good notes of all my flights, this is the main reason for me to be involved in flight simming - create my own flight planning tool, prepare all my flights as near as possible to real world procedures . . . and then the autopilot does the job and autoland function will finish the flight !Karl-Heinz - EDDI/THF " Tempelhof "" The mother of all airports " - Sir Norman Foster

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So how did the actual (MSFS) winds/temps compare to the FMC's initial programming? Since the FMC's preload data comes directly from the flight plan, the scratch pad is already available. Real-time temp and winds are there in the ND. Crews jot these numbers down too. If MSFS is providing non-standard temps and non-flight planned winds, the poor ol' FMC original burn/time estimates are gonna be wrong and get wrong-er. That's where the pilot comes in. IRL, we have gigantic flight planning departments with more computer hardware and years of experience that you can shake an FMC at . . . but the FMC still provides a critical double check. The flight plan does NoT have priority over the FMC's calculations. If the FMC's time/burn calculation is entirely out of whack with the flight plan, StoP EverYThing. Call your friendly mechanic to check out that FMC. Call Ops to check out that FP. But whatever you do (unless one has a death wish!), Do Not Launch till you find out why. The FMC is nothing more than a fancy calculator. That means the FMC's ability to process a data set and spit out a burn number will be very close to the multi-gazillion $$ department's ability to spit out that same number from that same data set. What does this all mean to us simmers? If we don't have that flight planning department handy, but only a data set, that lonely FMC will just have to do . . . and do it does, very nicely. It still appears the FMC encountered an environment in MSFS that was outside its initial flight plan programming. What part of MSFS's "reality" mismatched the original plan. The answer is probably there. For instance: "As soon I climbed up one step the fuel at dest went up . . . why ?" You caught a tail wind and/or thermal layer the FMC was not initially programmed to expect.I've been hoping we will have enroute ACARS weather download capability in the next versions - just like real life. But until then, the FMC simply will not have the data to accurately forecast variations ahead of the airplane. As it is now, unforcast variations are going to happen and effect burn numbers enroute, but it's not the FMC's fault.

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Hi Sam,Many thanks for your wise words. We must not expect to get away from the required professional attitude that all planning is just that - PLANNING. When we fly, we MUST take note of the actuals encountered and be prepared for discrepancies, and occasionally those discrepancies can lead to the need for professional judgements on alternative actions, including landing for extra fuel en-route. That is what professional pilots are paid to make potentially costly judgements about. It's just no good after crashing into the ocean to think that you can complain about an FMC 'that gave me the wrong numbers', it will certainly be too late. And that's why I like simming. Cheers, RichardNB The B744 crew fuel record software available from http:www.stevens-va.de may help some simmers to keep such records.

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. . . . ? ?>Hi Sam,>Many thanks for your wise words. Are they really wise . . .? I don't understand them :-hah>We must not expect to get away from the required professional>attitude that all planning is just that - PLANNING.This is actually just what I did . . . PLANNING ! Based on PMDG manual and about 1000 hrs of simulator time ! And I come out approx. +/- 1,5 ktons at destination ! :) > after>crashing into the ocean to think that you can complain about>an FMC 'that gave me the wrong numbers', it will certainly be>too late. This would be the case if the PMDG FMC would give fuel figures which are too HIGH - but they are permanently too LOW !!How can the PMDG FMC predict 8 hours ahead if the winds over Malaysia are different from what I entered 1 hour before take-off in Berlin ? With the information I got from the FMC as "pilot-in-command" I had to return to TXL and scream about the dispatcher or the fueller - when I receive a "insufficient fuel" message shortly after TOC ?!:-jumpyQTE "sam" : The Flight Plan does not have priority over FMC calculationsUNQTEIn Europe is the printed flight plan signed by the dispatcher and PIC the ONLY valid document for a trip from A to B - FMC data are only for rechecking and verification.But all this is not my point : to make it simple - with the help of my limited english language knowledge - :FMC is fed with ALL availabe data, like winds, weights, planned fuel, cost index and thereby speeds, initial altitude, altn and min ldg fuel, step climb info ( 2000ft or ICAO ) ( perf page FMC !! ), it should be able to calculate ( as a fancy calculator . . . ) the correct speeds, eta's and fuel remaining at all the planned waypoints ! It has nothing to do with upcoming meteological enroute environment since we are not yet AIRBORNE . . .! The funny thing is that the eta's are correct !! But the fuel calculation is deftly wrong because they are too HIGH and will be reduced then by the actual progress of flight - not because the winds are heavily different, the sector times are +/- 1 to 2 mins, the FF/min are calculated initially too high - one example between RASPU and TONSO the calc time was 40 mins for 370 NM and my calc called for 7.9 ktons of fuel at a rate of 197.5 kgs/min.the FMC calc was 8.5 ktons for 40 mins or 212.5 kgs/min.ACTUAL : 40 mins with 8.0 or 200 kgs/min !!DING DONG = "insufficient fuel" Fine ! Add another 10Ktons of fuel - it cost nothing in flight simming . . . !! But at the other end you arrive with tons of fuel which were not necessary !:-roll I sincerely hope I made my point clear, if not,I give up ! :-hahKarl-Heinz - EDDI/THF " Tempelhof "" The mother of all airports " - Sir Norman Foster:

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In the next couple of months, I'll have stacks of real 744 post-flight, pre-doodled flight plans to check the PMDG 744 FMC burn planning function against. It hard to argue with real world comparisons, but maybe that actual EGLL KLAX flight that matched so closely was just a fluke. Weirder things have happened, surely somewhere!Burried back in this obscure thread might be a good place to tell this story. I wouldn't put this on a front page, but I think we're a savvy enough crowd to consider this in the context of what really happens in this all-to-real world of ours. Somewhat on topic, it's about FMC calcs vs Flight plan calcs. Should the flight plan be considered the Holy grail? Hummm, consider this real life story. First a little background:Take-off is one of the most critical segments of any flight. Vspeed calculations are critical components of this procedure. Flight plans typically provide runway specific Vspeed calculations . . . so will the FMC. What do you do when these disagree? There's a whole school out there that agrees that the flight plan is the bottom line. If there's a discrepancy's between the FP and the FMC, the FP will be followed.There's a detail about the V1 calculation not generally understood. It's taken into consideration within the calculation, but crews don't use slide rulers and charts anymore. They use flight plans and FMCs. This detail is Vmcg. Velocity, Minimun Controllable, Ground. What is this? If an engine is lost after V1, the takeoff will continue in an assemetrical thrust configuration (sans a #2 tail engine). The airplane will still be flat on the deck, but yawing hard into the failed engine. The airplane has to be able to maintain heading while still on the ground. Otherwise, it will will depart the runway and crash. The speed that an airplane can maintain directional control with a worst-case engine out, while still on the ground is called Vmcg. It is absolutely critical that Vmcg be obtained by - at least- V1. Why? If it is not, there will be a window of catastrophe between V1 and when the airplane finally achieves Vmcg. If an engine fails during this window, the airplane will yaw into the failed engine. This is beyond V1, so the the pilot Must leave the remaining engines at TO power. He will feed in opposite rudder, but the airplane has not reached Vmcg. The rudder is now at the floor, but adequate lateral control is not yet available. The airplane is yawing off the ruwnay at TO power. Can you hear the voice recorder, "Help me. Right Rudder!" and then the tape stops. With the remaining engines at TO power, the airplane departs the runway and there was absolutely nothing the pilots could do. This inevitable, catastrophic result never happened to us, but it wasn't for lack of trying. We had MD11s coming out of heavy mod/maintenance from a desert location. This is normal event and management crews operate the intiial test/ ferry flight out of these maintenance events. These boys are the flyin' men and they really don't want those line guys beating up a heavy check airplane. As the post-discovery investigation reviled, these flights were scheduled for early-mid mornings depatures , however it always turned out that the airplane was actually departing this desert location mid-late afternoon. During their cockpit setup, these crews always had trouble getting the FMC to calculate Vspeeds. The LSK lines just stayed blank. Being completely confident in the capability of their Ops co-workers (and therefore the Flight Plan), they reasoned, "Well heck, that's what we have a flight plan for, right?" They'd just manually enter the Vspeeds from the flight plan and blast off.Well, for some reason a (less socially influenced) Boeing MD11 test pilot got the duty of picking up one of there post-maintenance MDs. Just like before, it became a late afternoon, 0-HOT-thirty departure. He sat down and started punching the FMC and got the same thing. The FMC would not display Vspeeds. Well, he StoPPed - FlaT. This flight is NoT going till we figure this out. The cell phones all came out and a, eer, "multi-party" conference call ensued. "What's the problem here." "We've been flying this same flight for 2 years not. No one else has this problem." "I told you it was a mistake calling Boeing." "Etc." Every pressure lever was pulled. As it turned out, the FMC was refusing to provide Vspeeds for an absolutely life-saving reason. The actual V1 number didn't move much, but the later-day / higher ambient temperature re-calculated Vmcg to a higher value. Vmcg was recalculated to a value that was considerably beyond V1. Lets go slow here. Vmcg had moved out ahead of V1. Consider: If an engine fails before V1, thrust on all engines will be brought back to idle and asymetrical thrust will not be a problem. Vmcg is not about stopping, it's about going. If the engine fails after V1, the remaining engine(s) will stay at TO power and the TO will continue. Because Vmcg had moved out ahead of V1, Vmcg would Still not be available for another XY knots once the decision to Go (V1) had been committed. The power-on acceleration between V1 and Vmcg would leave the airplane vulnerable to a catastrophic engine-out, then runway departure event. If an engine failed after V1, but before Vmcg, it would likely cause an unsurvivable, fiery crash. There would be absolutely nothing the crew could do to save themselves.A game of Russian Roulette. . . . Click . . . CLicK . . . and they'd been doing this for years.But hey, they were following the flight plan. By maintaining a policy of (utterly myopic) flight plan adherence, one of the NTSB's findings would have been that the crew had followed the flight plan properly and had been right on this point. In this case, Dead Right. However all along, in its own (not so) subtle way, the FMC was virtually shouting, "You're the boss, but I will not be a part of this lunacy!" To the flight plan evangelists, I would remind this story. The FMC is a voting member, and the vote Must be unanimous.

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