Long-range problems.

[xkoote 57]

I have also noticed this too. Even if you're flying in clear skies in FS2004 condition, the fuel at destination keeps dropping and dropping. In my opinion the PMDG 744 also uses too much fuel. But I'm not certain if that is PMDG's fault or FS2004's. Because I think the temp/mach/altitude corellation in FS2004 is WAY off. I flew last time in FS2004 in ISA conditions. I set e certain weight, flew at a certain altitude and let her settle into cruise. From the manual I read off at .86 cruise what the flow should have been. It was quite a bit higher. But strange enough, the TAS was way too high too. It was something in the range of 10 to 15 knots higher. So I slowed down to the TAS given in the manual for ISA conditions and low and behold, the flow figures were right on target. Only I was flying Mach .82 i.s.o. .86.In my opinion FS2004 completely screws up the fuel model. But I have tested this only twice and I wasn't sure enough to post about this.The topic starter has stopped the route twice not because he was in a low fuel condition. It was because fuel just ran out. In real life as soon as fuel gets even close to min at destination according their plans, they divert. And that can be more than 20,000 lbs of fuel.Xander

[michal 44]

Be careful when using flight plans from this site. I often saw there flight plans that were highly suspect - adding significant amount of distance over the Great Circle distance. Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://www.hifisim.com/images/asv_beta_member.jpg

[Guest Boaz]

Always choose a Cost index of "0"And LRC...Always keep your ZFW low... Don't expect full load factors and supa long range luxury!Good flight plans also keep you out of the worst headwinds while doing this dreadful ORD flight! It is harsh flying west always! Especially when you have so many NMs to kill...Also use step climbs wisely...Boaz...

[xkoote 57]

Actually my test showed some mixed results. While it's true that the TAS/Mach corellation in FS2004 is bad, it doesn't really affect PMDG's 744 in an adverse way.In PMDG manual at 680k lbs and at FL350. All values were within limits. N1, FF etc. Only the TAS/IAS deviated significantly. While at .86 @ FL350, TAS should have read around 476. Instead it reads 496. That is a big difference.Here's a pic of what I mean. Compare these figures to the PMDG cruise table. Enter at 680,000 lbs at FL350 (Opt Alt)See how everything looks OK except the TAS/IAS.Xander

[Guest Paragon]

Your attachment doesn't work...atleast not for me??

[michal 44]

It works for me.But guys, I would be very careful in proclaiming that this product fails to convert between TAS/IAS/Mach - this is all part of standard atmosperical physics. I bet PMDG did not invent those formulas - they are well known and available at many places.As a matter of fact I found this table that let you do this conversion and at FL350, assuming standard atmospere, Mach 0.86 - TAS is in fact almost 500 kts (it is definitely NOT 476). So, no, unless someone proves otherwise there is nothing bad about TAS/Mach conversion here.https://ewhdbks.mugu.navy.mil/mach-as.htmMichael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://www.hifisim.com/images/asv_beta_member.jpg

[JRBarrett 3,034]

You should have been able to make it. I ran your flight plan through FOC2003 (using PMDG performance data) using the winds for today (11-20-2005) which were at least as strong (or stronger) than what you experienced re: headwinds.These figures are in KG rather than pounds, but it equates to the same ZFW you used... FOC predicted that you would indeed have needed almost full tanks all around...This adds extra fuel for 45 minutes of holding, and a 20-minute route reserveThe FOC2003 data file takes the extra fuel burn of PMDG into account.It does depend on you making the step climbs at the proper times.By this calculation, the aircraft should arrive with 18.3 metric tons (about 40,000 pounds) of fuel remaining.Did you actually fly to true fuel exhaustion, or were you basing your decision to discontinue the flight on the fuel prediction in the PMDG FMC?By the way, the route that Routefinder gave you is pretty far off from an optimal great circle path for KORD-VHHH. I'll work on a better one, and post it here...Jim BarrettB744-PMDG-CF PMDG CF6 PREKORDVHHH.001 SEQ001 RLS000 FUEL CALCULATION: ALL IN TO WEIGHT/FUEL BREAK DOWN: ALL IN TO BIAS 1060 ZFW 218.1 242.7 TAXI 2.00 TOF 173.1 175.1 VHHH 154.68 16.11 TOW 391.2 396.9 RR20 7.73 00.49 TIF 154.7 ALT* 0.40 00.15 LW 236.5 285.8 FR 5.50 00.30 REM 18.4 CF 0.00 HF 4.77 00.45 AIRPORTS: ALL IN TO MIN 175.08 18.30 ADD 0.00 ACT 175.08 NOTES :- Route exeeds 105 per cent of GC !- FLIGHT PLANNED WITHOUT ALTERNATE:- Holding Fuel (15 Min.) added as Alternate-Fuel- UWX DATA FILES IN USE : 20051120.06U / 20051120.12U / 20051120.18U- STOPS/EROPS NOT CALCULATEDRTE VIA : DCT-OBK / DCT-OBK / J101-BAE / J89-YWG / J596-YQD / NCA13-YESKA / J133-ANC / J501-SQA / J179-ENM / G583-MVE / V8-AWE / V7-CHE / Y12-HWE / Y14-JEC / V30-DGC / V28-FU / OTR30-MIKES / DCT-BOLOD / B576-APU / W4-HLG / A1-ELATO / DCT-GUAVA / (I07R-SOKOE)DIST 7163 GCI 106 CP H058 ESAD 8433 CRSM NCR FLIGHT PROFILE :BGOSH/F320 - YWG/F340 - ALPIM/F360 - JAGIT/F380 - BESAT/S1160 - IRKAN/S1160 - MVE/F381 - SAROM/F400 - ARIKA/F430 ************************************************************* !!! NOT FOR REAL FLIGHTS OR NAVIGATION - INFORMATION ONLY !!! *************************************************************

[michal 44]

>By the way, the route that Routefinder gave you is pretty far>off from an optimal great circle path for KORD-VHHH. Yeah, I am not thrilled by routes generated by Routefinder. I frankly don't think they have anything to do with realism and discontinued using this site. I strongly suggest this place for actual real life flight plans http://flightaware.com/This is what I found for two United 744 flights from KORD and VHHH just filed in the last 24 hours:PETTY GRB 5500N 08700W 6500N 08600W 7000N 08800W 7500N 09300W 8000N 11000W 8400N 14100W RAMEL G491 BABED G491 CZ G491 SULOK G218 MENOR G218 TMR B458 WXI A461 LIG R473 WYN W18 NLG W23 ZUH R473 SIERAPETTY GRB 5000N 08900W 5500N 09000W 6500N 09100W 7000N 09300W 7500N 09800W 8000N 11000W 8400N 14100W RAMEL G491 BABED G491 CZ G491 SULOK G218 TMR B458 WXI A461 LIG R473 WYN W18 NLG W23 ZUH R473 SIERAMichael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://www.hifisim.com/images/asv_beta_member.jpg

[Guest lou ross]

Just thought of this, but when you first thought you didn't have enough fuel, did you think about reducing power, lowering your mach number and fuel flow?louross.

[opherben 0]

Hi,he was cruising LRC, there is no better speed for still air range performance. CI is a given by the operator and his 40 is reasonably low, whose contribution to consumption increase is minimal.When encountering headwind, the pilot should increase airspeed for optimum range, not lower it.> Just thought of this, but when you first thought you didn't>have enough fuel, did you think about reducing power, lowering>your mach number and fuel flow?>louross.

[michal 44]

>he was cruising LRC, there is no better speed for still air>range performance. Nope. LRC by its very defintion is NOT your best range cruise. Cost Index = 0 gives you best range. (per official Honeywell FMC doc.)>When encountering headwind, the pilot should increase airspeed>for optimum range, not lower it.Increase relative to what? This can be very misleading. True, in the presence of headwind your best range speed goes up but it goes up relative to your best range in the case of no wind. So if no wind CI=0 is your best range then with the wind it will be a slightly higher CI. The higher the wind the higher the cost index resulting in best range.Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://www.hifisim.com/images/asv_beta_member.jpg

[Arnaud 0]

Fuel prediction decrease also on the real bird, but in a much lesserextent than on the PMDG though.On a side note, inputing the winds datas in the FMC doesnt seem toaffect the fuel prediction over destination(on the PMDG of course). I've seen that often on some long haul I've been flying.Having said that, it is a point developped on the SU1 list, Mr Randazzo said if I remember well that the FMC routines had been improved on order to make fuel predictions more accurate.Apart from this, doing flight plans in real life for a living for a real major airline, I've had hardly scheduled fuel stops for 747-400.For 747-200 and 747-300, yes, lots, but not with a 744, except when the departure airport is very limitating (high altitude field and thus low MTOW)

[opherben 0]

1. Flying for United? you are bound by their CI.2. LRC AT CI 40 is very close to LRC at CI 0. I believe that 10 Kt headwind affects range performance close to the effect of increasing CI that much.3. My profession being experimental flight test since 1972, I know aircraft performance intimately. BTW LRC you get from any user data such as manuals and FMC, is deliberately offset at 99% of best cruise performance, traded off for higher speed (right side of the NM/LB fuel curve). If users knew that, they could reduce speed by say 5Kt and gain a little range, assuming no headwind. Better, they could, using a pocket calculator, find the actual true best speed, by deviding ground speed by total fuel flow, for the FMC generated LRC speed, and two points quickly taken avoiding weight reduction, 5 and 10 KIAS slower.>>he was cruising LRC, there is no better speed for still air>>range performance. >>Nope. LRC by its very defintion is NOT your best range cruise.>Cost Index = 0 gives you best range. (per official Honeywell>FMC doc.)>>>When encountering headwind, the pilot should increase>airspeed>>for optimum range, not lower it.4. CI is a relationship between time-variable and fixed operator cost. And wind is wind. >Increase relative to what? This can be very misleading. True,>in the presence of headwind your best range speed goes up but>it goes up relative to your best range in the case of no wind.>So if no wind CI=0 is your best range then with the wind it>will be a slightly higher CI. The higher the wind the higher>the cost index resulting in best range.>>Michael J.>http://www.precisionmanuals.com/images/forum/pmdg_744F.jpg>http://www.hifisim.com/images/asv_beta_member.jpg

[Guest Paragon]

>Nope. LRC by its very defintion is NOT your best range cruise.

[xkoote 57]

Hmmm.....according to the navy website, in ISA conditions the TAS/CAS DOES seem to be close to 500/300. If so, the FS2004 corellation seems pretty close to reality. So why does it say in the PMDG manual that flying at .86 and at FL350 should yield a TAS/IAS of 476/276 ???Xander