guenseli 76 Posted September 21, 2013 Share Posted September 21, 2013 Hello, I normaly fly shorter routes, often less then an hour, e.g. Berlin - Hamburg etc. I encounter now, that PFPX always calculates the maximum achievable FL it seems. As example a flight from EDDT to EDDH, my NGX FMX gives me an OPT altitude of FL250. But PFPX gives me 300 - CI 25 is set everywhere. Inserting 300 now in the FMC it gives me "cruise alt not achievable", and indeed, the 737 can't get to FL300 in that short time. I have seen that with other flights too and wonder what would be the right operation here? Shouldn't PFPX also use lower level on such short flights? Even when I'm able to get up into the PFPX calculated FL, the T/C and T/D are next to each other ... many thanks, Günter Link to comment Share on other sites More sharing options...
FlightSimSoft.com 283 Posted September 22, 2013 Share Posted September 22, 2013 Just tested here a flight from EDDT to EDDH: Even with max payload the cruise altitude is calculated with FL280 and a cruise portion of 50NM. Can you post a sample plan? Link to comment Share on other sites More sharing options...
guenseli 76 Posted September 22, 2013 Author Share Posted September 22, 2013 Hello Christian, thanks for the support. Attached is the OFP PDF But even with your FL280, the NGX FMC gives me just 250. Should I follow the FMC and edit this values then manually in PFPX? DLH111 EDDT-EDDH (22 Sep 0845 UTC).pdf Link to comment Share on other sites More sharing options...
FlightSimSoft.com 283 Posted September 22, 2013 Share Posted September 22, 2013 There are many definitions for optimum flight level (Optimum for speed, cost, time etc...). So depeding on what 'optimum' altitude the FMC is calibrated to, differences may occur. However, you can adjust optimum altitude calculation in PFPX by changing the 'Altitude adjust' value in the PFPX Aircraft Editor. Using '-2000' would for example reduce the optimum altitude caclulated in PFPX by 2000ft. Link to comment Share on other sites More sharing options...
guenseli 76 Posted September 22, 2013 Author Share Posted September 22, 2013 hmmm... I've just seen the similar question in the Flightsimsoft Forum: http://www.topcatsim.com/forum/index.php?topic=1241.0 There's a guy with the example EINN to EGLL. I have tried this and get a normal FL230 for this route with the 777. Time for this route is given for about 00:52 If I let compute EDDT to EDDH with a time of 00:32 for the 777 I get FL320 That is more a calculation for a ballistic projectile Link to comment Share on other sites More sharing options...
SamyJay 1 Posted September 22, 2013 Share Posted September 22, 2013 If I let compute EDDT to EDDH with a time of 00:32 for the 777 I get FL320 That is more a calculation for a ballistic projectile Even if only select lower airways? Mit freundlichem Gruss / Best Regards Samy Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
guenseli 76 Posted September 22, 2013 Author Share Posted September 22, 2013 SamyJay, on 22 Sept 2013 - 18:46, said: Even if only select lower airways? no, then I have FL240, yes... But shouldn't that be choosen automatically by PFPX? Link to comment Share on other sites More sharing options...
jc75 0 Posted September 23, 2013 Share Posted September 23, 2013 Ive had this on various routes for various a/c giving me far too high a Cruise level or even a stepped climb to a level the a.c will never achieve. What ever the airways used, surely PFPX should be calculating the distance, vs the a/c performance, wind/weight etc and giving a realistic achievable level, which is what the FMC is technically doing (although that is not even taking into account wind at first) I think it needs a bit more tweaking, either in its calculation at PFPX level, or the performance files for the a/c need more refinement. Link to comment Share on other sites More sharing options...
guenseli 76 Posted September 30, 2013 Author Share Posted September 30, 2013 want this bump up bit... Shouldn't PFPX not calculate lower flightlevels on shorter routes automatically? Link to comment Share on other sites More sharing options...
D-AIZE 0 Posted October 1, 2013 Share Posted October 1, 2013 want this bump up bit... Shouldn't PFPX not calculate lower flightlevels on shorter routes automatically? +1 I posted this already in the German forum: Trying to plan a route from EDDF to EDDM with A320, always getting FL310 from PFPX. I actually never get that high, despite the fact that the route is limited to FL240. I was hoping that PFPX is not only calculating a route but also giving me correct flight levels without manual intervention. Thanks Stefan Link to comment Share on other sites More sharing options...
guenseli 76 Posted October 1, 2013 Author Share Posted October 1, 2013 PFPX does also not exist for real aviation, what then argument that something doesn't work like the real world? PFPX is a really great tool which is precisely calculating all aspects of my flights an all by pressing a button. So, I can't then not imagine that especially flightlevels should be the big exception where I have to edit manually. I have honestly no clue, but I do not think that a real OFP would send me onto FL340 on a 140 sm trip ... Link to comment Share on other sites More sharing options...
FlightSimSoft.com 283 Posted October 2, 2013 Share Posted October 2, 2013 I have honestly no clue, but I do not think that a real OFP would send me onto FL340 on a 140 sm trip ... E.g. The Boeing 737-800 Flight Planning & Performance Manual Short Trip Cruise Altitude table shows an optimum altitude of FL340 for a 150nm trip and 1 minute cruise portion. Link to comment Share on other sites More sharing options...
guenseli 76 Posted October 2, 2013 Author Share Posted October 2, 2013 Thanks Christian, I still do not understand, sorry. In my first post here, with a CI25, the 737 is - according to it's FMC - not able to get up to FL300 ... The question is, is PFPX now supposed to take this into it's calculations (as I might think it should) or not? Shouldn't PFPX seek for lower airways automatically at such short trips? Link to comment Share on other sites More sharing options...
FlightSimSoft.com 283 Posted October 5, 2013 Share Posted October 5, 2013 Jet airplane operate economically at high altitudes Even on short legs, high altitudes are required for optimum economy, at cruise portions as low as one minute PFPX auto-router takes the aircraft's optimum altitude into acount for route finding (On a leg EDDT-EDDH at low weight this is around FL310-FL320). So PFPX uses upper airways for automatic route finding. You can force PFPX to use lower airways only. Link to comment Share on other sites More sharing options...
guenseli 76 Posted October 5, 2013 Author Share Posted October 5, 2013 Thanks for answering. So, as I see it, as you say, PFPX does calculate it right? How is it then in reality? I (as captain) get my OFP with a FL300, I enter my datas in the FMC which tells me then "unable to reach FL300". (And indeed, the 737 can't go up as I see during the flight). Even my flightplan is then already filed in FL300 and have to be changed then ... What do I do now as captain ...? Just want to know how to do things right ... Link to comment Share on other sites More sharing options...
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