Accuracy of 747-400 FMC

[VHOJT 172]

It is a definite shame the FMC's fuel prediction decreases so markedly. I have been flying for 7 hours on a SIN/LHR flight and the estimate has now gone down by three tonnes!!! The winds have been very consistent with those planned/entered in the FMC too.Oh well!

[Qavion 19]

"1: Why in real life do they fill the planes full ofpassengers and fly from LAX to YSSY and I can't get mysimultor, which is supposidly the closest thing to the realdeal, to fly with 1/2 payload the same route. I have to dropmy pax/cargo down to about 1/3, and then I can get withinMTOW."Are you step climbing at the appropriate times?What Cost Index are you using?Are you planning your routes to give you favourable winds? (Airlines are using variable routes which may not use regular oceanic waypoints).Are you aware that airlines regularly have problems with this route? (offloading cargo is done in real life, too. Fuel stops sometimes have to be made in Brisbane).Qantas often uses the 747-400ER on this route (which uses an Auxilliary Fuel tank in the forward cargo). This means less restrictions, but having a fuel tank in the cargo area obviously reduces cargo.IMHO, the fuel issue is being blown way out of proportion here.Cheers.Q>

[DF9AA 0]

@ all,now I am really stunned . . . and surprised !:-hmmm1. What is Mr. Hines trying to tell us ?Yes, what are we doing with head/tail wind ? Just include it in our calculation . . .2. ?VHOJT? On my flights the FMC fuel predictions for fuel at DEST went BELOW res fuel at the BEGINNING of the trip and then went UP ( see my first posting )To sum it up : Fuel predictions of the FMC lacking correct fuel-flow data - they're much too high when first initialising the FMC with all relevant data and then during flight the fuel-flow figures per hour are going down considerably - to make it crystal-clear : I am not talking about wind and temp influence, just FF/hr ! After having INCREASED the cost index from 150 to 160 ( 165 ) my fuel-flow figures came somewhat closer to the first FMC estimates - they only deviate by mere 1,2 % down.

[Guest SIX]

Hey guys, I am on a horrific WIFI connection at a truckstop here in ATL. I will try to answer Q's questions and also throw some more fuel on the fire :) :(>>Are you step climbing at the appropriate times?YES, appropriate step climb profile is being used.>What Cost Index are you using?100 all the time. That is what a former 744 pilot said was used most of the time on tran-atlantic flights.>Are you planning your routes to give you favourable winds?No, I wish I knew how or had the means to. I use ASWXR for winds. I wish someone would do a tutorial on long haul wx flight planning.>(Airlines are using variable routes which may not use regular>oceanic waypoints).>Are you aware that airlines regularly have problems with this>route? (offloading cargo is done in real life, too. Fuel stops>sometimes have to be made in Brisbane).Why BBN? It is 500nm NORTH of YSSY. If your coming in from LAX it would seem that would be out of the way. I understood in the 747-200 days they would stop over in Fiji or Auckland. So, what is preferred: A full cargo bay and a heck of a lot less pax or a full pax compartment but an almost empty cargo bay? A good friend of mine used to run the Approach position at KDTW, he said there was a weekly JAL 744 flight that NET $1,000,000 on the cargo alone - the pax load was what we Americans call "gravy." I am sure it all depends on the route, the cargo and equipment your using. But, for right now, I am talking about going to OZ or Southeast Asia. >>Qantas often uses the 747-400ER on this route (which uses an>Auxilliary Fuel tank in the forward cargo). This means less>restrictions, but having a fuel tank in the cargo area>obviously reduces cargo.It has been a long, long time since I have said anything regarding the ER on this forum. But, I don't fully understand why PMDG modelled the standard ops 744. Why didn't they model the 744 and the ER. How much harder could it have been? That is another discussion for another day. All I know is I really enjoy stretching the living daylights out of this bird and landing with fumes. Sometimes I like being realistic and landing with minimums according to realistic rules and sometimes I like to be risky. I have never crashed due to lack of fuel, but I have had one of my outboards cut out before I could get to the gate! If your not already bored and reading another post, chomp on this for a minute. I can, and have many times, leave LAX, SFO, PDX, LAS or SEA for WMKK, WIII, WSSS and I even think WRRR (Bali) WITH a 3/4 cargo/pax payload. When I get there I have the 10,000 lbs of minum from LAX or LAS. From SFO, PDX or SEA I am within FAA minimums. I believe the FAA requires 24,000 lbs but the European minima is less and I don't know what most Asian minima is. If you know some of these numbers from Asia and the EU lay it out right here :). It is 8,000 miles (or just under) on the LAX and LAS. Is the winds that less of a problem coming in from the North? Even so, the forecasted fuel at the arrival is changing all the time. I have even left on a flight that said I would have 28,000 lbs of fuel and when I got there I had 6,000 lbs. All I have to build routes with is FSBuild 2.x and Routefinder (http://rfinder.asalink.net/free). I just build the route and cross my fingers and I am sick of it. I usually spend about twenty minutes in route planning as I will usually tweak the generated routes a little bit and I do that in FSNav and I use current charts (or as current as I can get - I use Sporty's Charts which are up-to-date current cycle on DVD mailed out each month and I use Navigraph for my Asian Charts and I use the UK service for the UK and the VATSIM Euro site for my German charts, if Navigraph isn't up to par. I really, really want to step up my planning to the next level. BTW, just a note here I use FS2Crew for added realism and I find it has been a real kick in the can!!!! I highly recommend it to everybody who breaths and takes this gig even half serious.>>IMHO, the fuel issue is being blown way out of proportion>here.I dont' think we are blowing it out of proportion as this is the thing that irritates me most. :)>Cheers.>Q>I sure hope this all makes sense. Thanks for the time you have spent reading and responding to my random and yet nutty thoughts.Wilson HinesMy Blog: http://www.wilsonhines.com --------------------------------------http://www.precisionmanuals.com/images/forum/747400.jpghttp://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://online.vatsimindicators.net/837438/3074.png

[Qavion 19]

"Why BBN? It is 500nm NORTH of YSSY. If your coming in fromLAX it would seem that would be out of the way. I understoodin the 747-200 days they would stop over in Fiji or Auckland."BBN is north and slightly east of sydney, LAX is northeast of SYD. BNE is closer to LAX by quite a few tonnes of fuel."So, what is preferred: A full cargo bay and a heck of a lotless pax or a full pax compartment but an almost empty cargobay?"Cargo always loses to pax. Pax get more upset than cargo if they are offloaded... and you don't have to put cargo in a fancy hotel room for the night with spending money ;-) "It has been a long, long time since I have said anythingregarding the ER on this forum. But, I don't fullyunderstand why PMDG modelled the standard ops 744. Whydidn't they model the 744 and the ER."The differences between the 744 and the ER are a lot more than cosmetic (and there are a lot of differences)... Not that I'm downplaying how hard it is to create new bitmaps, new VC's, new mouse mapping for the panels, new menus, etc, etc. It would add months to the release date and to be honest, there aren't many people on this planet who understand the logic/physics behind the AUX tank feed. The REAL 744ER design is still a work in progress... There are still minor bugs in the system. Software upgrades are pending). Overall, there really is a lack of data on this aircraft. AFAIK, only one person on the team has worked on the ER.. and then only occasionally. You may have noticed that PMDG get a lot more complaints from people wanting their sims YESTERDAY than people wanting the ER. Only 2 or 3 airlines fly the ER. Producing an ER would almost be as difficult as producing the Cargo version. How many simmers actually fly these 14~15 hr sectors anyway (compared to short- haulers)? I think if you were on the PMDG team, you would understand the pressures of producing a sim and the decision-making process.And that's all I'm going to say on the subject of the ER, my friend (as I've said it all before)Cheers.Q>