pvupilot 2 Posted November 16, 2013 Share Posted November 16, 2013 Hey guys, I've been using PFPX since close to when it came out but mainly on shorter flights with the occasional long haul. I've never ran out of fuel (came close once with the PMDG MD-11) and usually have too much extra. Well I decided to push my system, PMDG 777, and PFPX on a super long haul. I loaded up PFPX and put only 2 passengers and zero cargo for payload. O also skipped ETOPS and put no alternate. I put 30 minutes for extra time. When it tried to calculate the fuel, it came up saying I will be short -84,000lbs of fuel. I loaded tanks 100% anyways and decided to go ahead and see what would happen. Well, I landed at the destination with plenty left (over 14,000lbs) which brings me here. Why was PFPX off by so much? 98,000lbs of a fuel miscalculation sure isn't a "small" mistake. I used ASE for both PFPX weather and FSX weather. Here is a little more info of my route: VHHH-EHAM OCEA2A V3 ENVAR M750 MJE PETAL OTR14 VACKY OTR13 SEALS 36E50 38E60 40E70 40E80 38N71 36N61 36N51 36N41 35N31 AUDIA LAX J146 JFK PUT BOS TUSKY N63B VIXUN LOGSU 4950N 5140N 5230N 5320N MALOT BURAK UN536 DUB UL975 WAL UM16 DOLAS UL603 LAMSO LAMS1A Thanks! Link to comment Share on other sites More sharing options...
dougsnow 50 Posted November 16, 2013 Share Posted November 16, 2013 My guess without seeing your fuel plan is that PMDG is off. The model in Pfpx is built using real world professional performance tools; the same tool an airline would use creating their perf data for their flight planning system. Is PMDG? Link to comment Share on other sites More sharing options...
dougsnow 50 Posted November 16, 2013 Share Posted November 16, 2013 Plus, now that I look at the route, who in their right mind would fly that route? Show me an airline who could fly that in real life. Link to comment Share on other sites More sharing options...
phil747fan 52 Posted November 16, 2013 Share Posted November 16, 2013 Doug, just to test endurance no .... lol Link to comment Share on other sites More sharing options...
tcasclimb 0 Posted November 17, 2013 Share Posted November 17, 2013 Weird, how the heck could you have done this in ANY 777, the route is over 14,000nm long, something else is wrong, are you sure you dont have unlimited fuel checked in FSX? Link to comment Share on other sites More sharing options...
E6BAV8R 0 Posted November 17, 2013 Share Posted November 17, 2013 Plus, now that I look at the route, who in their right mind would fly that route? Show me an airline who could fly that in real life. What difference does it make if it is a real world route or not? You do realize this is flight simulation, right? Link to comment Share on other sites More sharing options...
dougsnow 50 Posted November 17, 2013 Share Posted November 17, 2013 What difference does it make if it is a real world route or not? You do realize this is flight simulation, right? Why yes I do, but since the performance model is based on real world performance, using real world professional software used by airlines... Plus, the question to be asked is did he fly the planned profile? At the planned speeds? With the planned step climbs? With the planned payload? Did he complete a flight log? Did he use time compression? If he is going to harp after a whopping 11 posts that the fuel model for a given airplane is out of whack, the least he could do is to present a little more than at best minimal evidence to support the charge with a completed flight log... Like United Airlines says in a pilot training guide - fly the plan you sign for... I still hold that the model in PMDG is off. In the recent worldflight, I flew a full size B747-400 Flight Sim for 3 legs, and was FO for three in Australia. The bias that was required for PFPX to accurately calculate required fuel was 25%. But, once that fuel bias was added to the aircraft record, PFPX was dead on accurate. Link to comment Share on other sites More sharing options...
re84uk 16 Posted November 17, 2013 Share Posted November 17, 2013 Problem is, if one is using the PMDG 777 profile within PFPX, one expects it to somewhat match PMDG's fuel performance figures, not the real aircraft. The fact that the profile was built using real performance tools etc is irrelevant as the profile should be constructed with the PMDG 777 in mind. Just my thoughts Link to comment Share on other sites More sharing options...
tcasclimb 0 Posted November 17, 2013 Share Posted November 17, 2013 Problem is, if one is using the PMDG 777 profile within PFPX, one expects it to somewhat match PMDG's fuel performance figures, not the real aircraft. The fact that the profile was built using real performance tools etc is irrelevant as the profile should be constructed with the PMDG 777 in mind. Just my thoughts And here are my disagreeing thoughts I dont think that is a fair expectation, why should it be constructed with the PMDG 777 in mind? Why not CSs 777 or some freeware 777? I prefer that they start out with real world data, then give us the option (as they have done) to tweak the performance file to the various other models of 777s available for FSX, Xplane and P3D (all of which i can almost assure you would have different performance values), that would be much easier in my opinion than catering for 1 specific product then have some of "those types" of characters coming on here saying things like "arghhh why didnt you create the profile off this model, blah blah blah", now the same thing could be said for "arghh why did you use the real aircraft data, why didnt you use blah blah blah" but keep this in mind, FSS made PFPX in a realism oriented way, which many of us are very happy with, it would only make sense to include real aircraft performance data, wouldnt it? For them to have included the PMDG 777s performance data (a fairly accurate one) would have set PFPX release date much later as, 1 they would have to wait until the PMDG 777 was released and buy it 2 they would have to sit down and fly the plane, in a huge number of configurations, climb cruise and descent at weights ranging from empty to max takeoff weight and at different speeds and cost indexes, with and without anti ice on, not to mention collecting the data for single engine cruise AND driftdown performance. All of this done at different ISA temperature deviations. You should be able to see, that without all this information, already nicely laid out in performance charts etc (which PMDG has not included in their manuals to this level of detail), this would have been a huge task for creating just 1 aircraft profile, and we havent even started talking about the time it takes to create the PFPX program itself and fix the major show stopping bugs and get it to do all the wonderful things it currently does. So using real world performance charts (which they already have at their disposal) only makes sense and is a much quicker process. Link to comment Share on other sites More sharing options...
srcooke 422 Posted November 17, 2013 Share Posted November 17, 2013 The OP has not yet returned with any data on which to validate either way. The flightplan submitted by the OP when entered into PFPX is clearly not correct. Link to comment Share on other sites More sharing options...
re84uk 16 Posted November 17, 2013 Share Posted November 17, 2013 And here are my disagreeing thoughts I dont think that is a fair expectation, why should it be constructed with the PMDG 777 in mind? Why not CSs 777 or some freeware 777? I prefer that they start out with real world data, then give us the option (as they have done) to tweak the performance file to the various other models of 777s available for FSX, Xplane and P3D (all of which i can almost assure you would have different performance values), that would be much easier in my opinion than catering for 1 specific product then have some of "those types" of characters coming on here saying things like "arghhh why didnt you create the profile off this model, blah blah blah", now the same thing could be said for "arghh why did you use the real aircraft data, why didnt you use blah blah blah" but keep this in mind, FSS made PFPX in a realism oriented way, which many of us are very happy with, it would only make sense to include real aircraft performance data, wouldnt it? For them to have included the PMDG 777s performance data (a fairly accurate one) would have set PFPX release date much later as, 1 they would have to wait until the PMDG 777 was released and buy it 2 they would have to sit down and fly the plane, in a huge number of configurations, climb cruise and descent at weights ranging from empty to max takeoff weight and at different speeds and cost indexes, with and without anti ice on, not to mention collecting the data for single engine cruise AND driftdown performance. All of this done at different ISA temperature deviations. You should be able to see, that without all this information, already nicely laid out in performance charts etc (which PMDG has not included in their manuals to this level of detail), this would have been a huge task for creating just 1 aircraft profile, and we havent even started talking about the time it takes to create the PFPX program itself and fix the major show stopping bugs and get it to do all the wonderful things it currently does. So using real world performance charts (which they already have at their disposal) only makes sense and is a much quicker process. Because when I choose the PMDG 777 template in PFPX, I expect it to match the PMDG 777. Just the way my brain works I guess. Link to comment Share on other sites More sharing options...
srcooke 422 Posted November 17, 2013 Share Posted November 17, 2013 Because when I choose the PMDG 777 template in PFPX, I expect it to match the PMDG 777. Just the way my brain works I guess. Post your plan and actual figures for comparison so at least if necessary a solution may be found, as yet nobody has done that. Link to comment Share on other sites More sharing options...
re84uk 16 Posted November 17, 2013 Share Posted November 17, 2013 Post your plan and actual figures for comparison so at least if necessary a solution may be found, as yet nobody has done that. I myself don't have a big problem with fuel discrepancies, I'm just expressing my opinion in regards to the aircraft profiles. I feel they should match (within a certain tolerance of course) the add on manufacturers aircraft and not necessarily the real one. Otherwise, may as well have just one profile per aircraft type (I know the 777 only has the PMDG one). Just my feelings and some people are bound to disagree. Link to comment Share on other sites More sharing options...
phil747fan 52 Posted November 17, 2013 Share Posted November 17, 2013 the add-ons has been input to help the users of those add-ons but they re not stone written up to the end. they can be adjust to your founds or likes. this is the base. but the datas are certainly very accurate as they re the one provided to airlines and as we already had that discussion with Doug on the creator forum if the results from an add-on are away from what PFPX found sorry again this is not PFPX fault. just taylor with your needs. Phil Link to comment Share on other sites More sharing options...
pvupilot 2 Posted November 18, 2013 Author Share Posted November 18, 2013 Weird, how the heck could you have done this in ANY 777, the route is over 14,000nm long, something else is wrong, are you sure you dont have unlimited fuel checked in FSX? Yep, my unlimited fuel is unchecked in FSX. Why yes I do, but since the performance model is based on real world performance, using real world professional software used by airlines... Plus, the question to be asked is did he fly the planned profile? At the planned speeds? With the planned step climbs? With the planned payload? Did he complete a flight log? Did he use time compression? If he is going to harp after a whopping 11 posts that the fuel model for a given airplane is out of whack, the least he could do is to present a little more than at best minimal evidence to support the charge with a completed flight log... Sorry for the late response, college finals are nearing and I've been a bit busy since the post, on top of not receiving emails when new posts are made (Not sure why not). I have since removed the OFP from PFPX but I can recreate the exact same OFP and post here. Yes it is PMDG 777. The route IS a real world route flown by a test 777 http://www.nytimes.com/2005/11/10/business/11air.html?_r=0 I flew everything to exactly the OFP PFPX gave me, and even towards the end of the flight I descended a little lower and picked up airspeed due to "Low fuel temp" warning. This could perhaps provide a little more info on flight data: http://www.deltava.org/pirep.do?id=0xeba35 I used zero time compression. I didn't see myself as "harping" and I didn't know exactly all the information I needed to give so I gave what I knew would be at least a good start (# of PAX, cargo weight, no ETOPS calc, no alternate, 30 mins extra fuel, flight plan, and weather program used). The reason I came here is to get help and see if there could be a possible answer, not to "harp". 11 posts shouldn't have much to do with it. Just because I'm not actively posting doesn't mean I don't come here to look for answers/updates. Probably the reason why I have so few posts here is because I can usually find my answer by searching and when I can't, I will make a topic. Anyways, I'll try to get that OFP here as soon as I can. Link to comment Share on other sites More sharing options...
tcasclimb 0 Posted November 18, 2013 Share Posted November 18, 2013 I just figured out whats going on. There is a waypoint in the flight plan, BURAK which is over Ukraine somewhere which caused the route to be drawn over the Ukraine and then back to EGLL which is why the distance was over 14000nm, removing this point brings the distance down to 12020nm and a flight time of 22hrs and 14mins, and the fuel required is now within the tank capacity of the 777, you dont even seem to need the auxiliary tanks if you plan using the NO RESERVES policy. This was supposedly the flight plan of this particular flight, slightly longer and with PFPX's current weather takes around 22hrs and 42mins, on par with that article that said it was 22hrs and 41 mins. OCEA2A OCEAN V3 CONGA/N0495F330 V3 ENVAR/N0495F330 M750 MANEP Y753 JAKAL A1 ALBAT/N0485F350 A1 KEC OGASA MORAY/M083F350 34N150E 32N160E 33N170E 35N180E 36N170W 39N160W 43N150W 44N140W/M083F370 42N130W/N0477F370 VESPA C1486 ENI J143 PYE J88 ROBIE/N0487F390 J88 LAX J60 BLD J107 MLF J9 FFU J202 OCS J94 BFF OBH J10 IOW J60 PSB J78 MIP J146 JFK J225 PVD J55 BOS J575 YQY VIXUN LOGSU 49N050W 50N040W 52N030W 53N020W/N0467F390 MALOT/M083F390 UL9 BURAK/N0466F390 UL9 STU UP2 NUMPO Y3 NIGIT Link to comment Share on other sites More sharing options...
dz111 11 Posted November 18, 2013 Share Posted November 18, 2013 The performance data for the Boeing 777-200LR is not based on the PMDG and in fact has existed since before the PMDG was released to public. Another glaring proof that it isn't based on the PMDG is the fact that the 4% bias programmed into the PMDG template works like magic. If the data was spot on the PMDG model, a 0% bias would work much better. Link to comment Share on other sites More sharing options...
re84uk 16 Posted November 18, 2013 Share Posted November 18, 2013 The performance data for the Boeing 777-200LR is not based on the PMDG and in fact has existed since before the PMDG was released to public. Another glaring proof that it isn't based on the PMDG is the fact that the 4% bias programmed into the PMDG template works like magic. If the data was spot on the PMDG model, a 0% bias would work much better. So why is the template called PMDG 777? Link to comment Share on other sites More sharing options...
tcasclimb 0 Posted November 18, 2013 Share Posted November 18, 2013 So why is the template called PMDG 777? because its a Template, it is created with the passenger numbers, fuel quantity and cargo capacity of the PMDG 777, there is another section inside the template, the type, which is where you choose the aircraft type, which has the (fuel burn and planning) PROFILE tied to it, and another section where you can set the (takeoff and landing) PERFORMANCE module. Link to comment Share on other sites More sharing options...
re84uk 16 Posted November 18, 2013 Share Posted November 18, 2013 because its a Template, it is created with the passenger numbers, fuel quantity and cargo capacity of the PMDG 777, there is another section inside the template, the type, which is where you choose the aircraft type, which has the (fuel burn and planning) PROFILE tied to it, and another section where you can set the (takeoff and landing) PERFORMANCE module. ah ok, so the aircraft type chose within the template profile is what has the performance data attached to it? that would make a lot more sense. Link to comment Share on other sites More sharing options...
MD-82 3 Posted November 19, 2013 Share Posted November 19, 2013 For what it's worth I had a thread in here and asked what data PFPX used. It was FCOM's. The reply was that it was tools much more accurate and advanced than FCOMs. Since then I have adjusted the fuel flow scalar of my PMDG 777. And I like it a lot now. The only thing I would like to see implemented is the 777 fuel/drag adjust figures. Then anyone can set fuel performance as they with and make it all agree. I have sent a ticket to PMDG and they said they'll think about activating the feature. I match all and all PFPX figures. I even set the Top of Climb fuel in the third FMC and make note of the CG (after setting the correct payload of course) so I can set the correct CRZ CG in the FMS instead of the standard 14% in the 777. Don't even know if it affects the fuel burn in the PMDG. I have covered all the settings and have now adjusted my PMDG to match PFPX. Xander Link to comment Share on other sites More sharing options...
phil747fan 52 Posted November 19, 2013 Share Posted November 19, 2013 For what it's worth I had a thread in here and asked what data PFPX used. It was FCOM's. The reply was that it was tools much more accurate and advanced than FCOMs. Since then I have adjusted the fuel flow scalar of my PMDG 777. And I like it a lot now. The only thing I would like to see implemented is the 777 fuel/drag adjust figures. Then anyone can set fuel performance as they with and make it all agree. I have sent a ticket to PMDG and they said they'll think about activating the feature. I match all and all PFPX figures. I even set the Top of Climb fuel in the third FMC and make note of the CG (after setting the correct payload of course) so I can set the correct CRZ CG in the FMS instead of the standard 14% in the 777. Don't even know if it affects the fuel burn in the PMDG. I have covered all the settings and have now adjusted my PMDG to match PFPX. Xander Xander, in the case of the 777 this is not data from FCOM for sure ... but the newer version of BPS 2.0 so the refinement is there ... there is not enough datas in any Boeing FCOM to build a profile. FPPM yes but that is another story. Phil Link to comment Share on other sites More sharing options...
MD-82 3 Posted November 20, 2013 Share Posted November 20, 2013 Yes Philippe, I think it was you that told me that last time. After some mods I am now really please with my planning results. Thanks again. Link to comment Share on other sites More sharing options...
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