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Constantly too late TOD ! http://www.ocs-support.co.uk/forums/viewtopic.php?t=1972 |
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Author: | ThomasAH [ Sat Apr 02, 2016 12:01 pm ] |
Post subject: | Re: Constantly too late TOD ! |
PF3 could have issued the descent calls at 16:43 instead of 17:01, so there is room for improvement. I agree with that. He did. He did. They didn't. (And I would assume that in the context of your earlier messages this would trigger a negative reaction with other people, so please try to avoid that) Certainly nobody expected PF3 to wait 18 minutes. Additionally I'm not sure if PF3 would have been happy with that. Will the cruise altitude be recalculated in this case? I think yes, but I don't know for sure. |
Author: | vololiberista [ Sat Apr 02, 2016 12:07 pm ] |
Post subject: | Re: Constantly too late TOD ! |
I think the main problem here was that the cruise altitude was set too high with regard to the aircraft's performance. The flight is the equivalent of London to Paris and FL250 is the max for that leg. The VC10 climbs like a rocket in all but the highest temperatures so in my re-run of this fpl I was well able to get to FL340 in time. Even the fpl ZJSY to VHHX (which is 405 nm not 284nm as in Martin's) my cruise level was only FL240! So my suggestion to Martin is to knock ten grand off the cruise level and try again. From Dave's point of view how would he programme a module to compare a fpl with the aircraft's performance in order to avoid this situation of climbing too slowly? And if I was flying a 747 freighter all the way from Europe to the Far East I would certainly have to manually add step climbs to PF3's basic plan. I can't see how PF3 would be able to reprofile a fpl according to a/c weight and performance. |
Author: | Dan77 [ Sat Apr 02, 2016 12:42 pm ] |
Post subject: | Re: Constantly too late TOD ! |
Maybe throw a warning if cruise is set above a certain ratio relative to length of flight? This value would need to be arbitrary and a warning only, as aircraft specs differ and the pilot would need to make the determination. As far as not reaching cruise by the time one reaches TOD, that could be a problem. |
Author: | awralls [ Sat Apr 02, 2016 1:17 pm ] |
Post subject: | Re: Constantly too late TOD ! |
What I'm slightly baffled by is that if the user has set an accurate profile in for the aircraft in use, this could easily be checked against basic climb-cruise-descent speeds and climb and descent rates. It's this element that should be driving the calculation of initial TOC and TOD points and whether or not these are viable. As long as the user has entered it correctly, the data is all there. In the cases where I've experienced late or non existent descent instructions, it seems that these figures have been either miscalculated or not factored in because I have entered very conservative figures and they are not being respected by the code (that I can see). If you want to check it out, the log of one of my recent flights is in the thread 'Oceanic Procedures (again)'. Just a thought.... Andy |
Author: | ThomasAH [ Sat Apr 02, 2016 1:19 pm ] |
Post subject: | Re: Constantly too late TOD ! |
He does not have to: If the TOD is reached, issue descent instructions, even if the cruise altitude hasn't been reached yet. This makes a strange flight, so setting a lower cruising altitude would indeed be better, but at least it results in a workable approach. Nice idea. PF3 has the climb rate from the preset and rough speed estimates from the aircraft.cfg or PF3 preset, so with a similar calculation as for the TOD, PF3 could calculate a rough estimate of the TOC. If both are too close: Warn. Or if the TOC beyond the middle (or 40% or whatever) of the fpl distance: Warn. On the other hand there already are flight planners that know the aircraft specs, so they could issue a warning here, too. |
Author: | vololiberista [ Sat Apr 02, 2016 1:32 pm ] |
Post subject: | Re: Constantly too late TOD ! |
It's not just the basic a/c spec though. Weight and temperature have a significant effect on climb performance. As I said a 747 on a hot day really struggles. I agree though that if the TOD wypt is reached then a descent call to that of the next wypt be issued regardless of the a/c "actual" altitude. |
Author: | ThomasAH [ Sat Apr 02, 2016 1:55 pm ] |
Post subject: | Re: Constantly too late TOD ! |
Andy, your log looks similar to Martin's, except that you have reached your cruise altitude in time and still did not get descent instructions after PF3 logged "Reached TOD". And what's stange: None of the 54 logs I have kept for bug reports contain this phrase! But this might be due to the descent rate of 1500fpm combined with low cruise altitude (max. FL190) and slow speed (max. 160 knots), which results in TOD distances of 10-30 NM. |
Author: | awralls [ Sat Apr 02, 2016 3:02 pm ] |
Post subject: | Re: Constantly too late TOD ! |
Thanks for checking it out, but now it gets weirder... My cruise alt was actually FL250 (I have the FSCaptain log which shows this) and my profile descent rate should have been 500 rpm, not 1500fpm, which would explain why I was not getting any meaningful descent instructions. Therefore, if the figures you're quoting are from the PF3 logs, something is even more amiss since they don't represent the actual flight parameters I fulfilled. Andy |
Author: | Dave March [ Sat Apr 02, 2016 3:55 pm ] |
Post subject: | Re: Constantly too late TOD ! |
It makes no difference whatever the total distance of the FP is, a TOD is a TOD and the total distance does not form part of the calculation. Cruise was 34,000, FAF altitude was 2,000 so difference was 32,000' With a GS of about 440 knots 236 miles would be correct. The problem here is the TOD didn't get triggered and it should have done... in this case, due to the short distance, as soon as the aircraft reached TOC. Currently there's no way of know what GS PF3 was using but I've now added it to the logging |
Author: | ThomasAH [ Sat Apr 02, 2016 5:19 pm ] |
Post subject: | Re: Constantly too late TOD ! |
No, FL190 and 1500fpm where my settings, not yours. Your log correctly had FL250/500fpm. |
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