Jump to content

Archived

This topic is now archived and is closed to further replies.

Recommended Posts

Hello,I have about 150+ hours on the MD-11 but every descent I ever have had the TOD calculated from the FMS was too late so I end up using the speed brakes during the better part of the descent. This occurs in policy descend mode and in the ECON mode. If I start an early descend (pulling the altitude button at a lower altitude and then pressing profile a bit later) the aircraft flies at a very small vertical speed until it comes to the FMS calculated glide path where it later tries to follow it but fails ending up with ("speed error at x" and "altitude error at x"). Even when I am flying at FL70 and should descend to 5000 feet the airplane isn't able to either hold speed or make the altitude constraint. Even after I have entered correct forecast wind speeds.Is there anyone else who has experienced the same problem or can help me? Manfred Win 7Q66008 gig RAM9800 GTX+

Share this post


Link to post
Share on other sites

Manfred, this is an issue in the real one too ... seems to fool the fms/fmc the pilots were/are adding 50 knots of tailwind ... this is not a tip given during transition but it was given by two different pilots when i was doing a profile for FOC ... the descend speed should be 320/.82 then maybe input 340 KiAs ... another tip ... plus there is still the rule of thumb for the TOC of 3 times +10 ... lets say you re at 35000 you should start descent at 115 nm (35x3 +10)of course with tailwind you add +10 and head wind you didnt count +10 ... seems too that some PMDG pilots already reported thathttp://forum.avsim.net/topic/261559-md11-rnav-app-jfk-rw31r/ have a great day.

Share this post


Link to post
Share on other sites
Hello Manfred,just to make sure, the engines are in IDLE when you're descending, right?
Well not always, only when the ###### really hits the fan (is that the correct expression tongue.png), usually the airplane uses thrust but at a very low power.
Manfred, this is an issue in the real one too ... seems to fool the fms/fmc the pilots were/are adding 50 knots of tailwind ... this is not a tip given during transition but it was given by two different pilots when i was doing a profile for FOC ... the descend speed should be 320/.82 then maybe input 340 KiAs ... another tip ... plus there is still the rule of thumb for the TOC of 3 times +10 ... lets say you re at 35000 you should start descent at 115 nm (35x3 +10)of course with tailwind you add +10 and head wind you didnt count +10 ... seems too that some PMDG pilots already reported thathttp://forum.avsim.n...-app-jfk-rw31r/ have a great day.
Thx for the elaborate answer :) But this brings some new questions and statements:
  • Is there a smarter way to fool the autopilot because if I for example do a descent against the wind and then have land in the opposite direction the 50 knots of tailwind suddenly become 50 knots of headwind witch would defeat the purpose of the trick (unless you constantly change the wind).
  • The decend speed usually is between 320 and 340 knots but the problem is that if I don't use the spoilers the aircraft overspeeds until the overspeed protection kicks in, somehow the decent is so steep that even at high and low altitudes the aircraft isn't able to maintain the descend path...
  • sorry but I didn't buy a 79 dollar airplane for a useless descend calculator and I doubt that the real airlines would have accepted such FMS since their cost index calculations would be useless too. Hasn't McDonnell Douglas or Boeing come up with a patch for the FMS?
  • I have read through http://forum.avsim.n...-app-jfk-rw31r/ but the problem he had was with an RNAV approach but my problem is regarding ALL descending constraints... There isn't a single altitude constraint in the descent witch the MD-11 can hold..

Is there anyone else having the same problem? I really love the MD-11 but this problem is kind bugging me... Manfred

Share this post


Link to post
Share on other sites

Manfred, it was a known problem for the real md11 users so im pretty sure the PMDG did the same way. to avoid that you should follow your own way to pilot and not letting the computer doing what he s programmed for ... the md11 is not made the same way as a Boeing. this is not a Boeing (Boeing buy back Mcdonnell after MD11 development) so the philosophy is defintely not the same. i can tell you : i was able to fly the DC10-30, 737, 747 classic and -400 simulators without any instructions but the airbus A320 and 330/340 no way ... pretty sure the MD11 is on the same way and philosphy as the airbus ... the MD11 is flying on approach faster so there is another to do. dont own the PMD11 and i ve made only a flightplanning profile for the md11 but again my fellow friends that flew the MD11 says the pmdg model and behaviour was really close. so in fact it s another way to learn to fly. you have a problem during approach as the other link given to you so this is not only you or their methods but the way this plane should be flown ... ill try to find some infos in my own MD11 FCOMs but dont hold your breath on it. ps if you have to fool the autopilot as stated on 1 maybe follow this. it was given by real pilots so nothing coming from a magician hat ...

Share this post


Link to post
Share on other sites
Manfred, it was a known problem for the real md11 users so im pretty sure the PMDG did the same way. to avoid that you should follow your own way to pilot and not letting the computer doing what he s programmed for ... the md11 is not made the same way as a Boeing. this is not a Boeing (Boeing buy back Mcdonnell after MD11 development) so the philosophy is defintely not the same. i can tell you : i was able to fly the DC10-30, 737, 747 classic and -400 simulators without any instructions but the airbus A320 and 330/340 no way ... pretty sure the MD11 is on the same way and philosphy as the airbus ... the MD11 is flying on approach faster so there is another to do. dont own the PMD11 and i ve made only a flightplanning profile for the md11 but again my fellow friends that flew the MD11 says the pmdg model and behaviour was really close. so in fact it s another way to learn to fly. you have a problem during approach as the other link given to you so this is not only you or their methods but the way this plane should be flown ... ill try to find some infos in my own MD11 FCOMs but dont hold your breath on it. ps if you have to fool the autopilot as stated on 1 maybe follow this. it was given by real pilots so nothing coming from a magician hat ...
Wow, that info you came with is kinda cool, I didn't know all that stuff. But i would still like to have it confirmed by an PMDG MD11 user that the descent is so off normal, I mean after a descent of 20000 feet I end up 5000 feet too high. That's an extreme amount... Also I wonder how the decent is? Is it always with idle power or does the aircraft use thrust decent, mine uses mostly thrust. Is it normal that when you during a decent have descent of 3000feet/20nm (which isn't much) the aircraft still misses it. The aircraft will end up flying at the same altitude and about 2 nm before the constraint it will try to descent end tell in the FMC "xxxx altitude error". Is it normal that the aircraftduring a normal descend overspeeds... I understand that the real FMC but I wonder what the PMDG MD11 users say (and I hope someone will answer) :( It would be awesome if you could find some of you own FCOM, all kind of info is heavily appreciated :) Manfred

Share this post


Link to post
Share on other sites

You also need to input any "EXPECT TO CROSS AT ..." restrictions on your own. Unless it's an RNAV profiled STAR, it's just going to calculate based on whatever optimal profile it selects. If you see a crossing restriction as "EXPECT..." put it in the FMC and you'll get a more accurate prediction. It follows the old adage:"[stuff] in, [stuff] out." If you don't give it good info, it'll give you back whatever it can figure out on its own. If you help it out and give it good info, you're golden.

Share this post


Link to post
Share on other sites

Scandinavian, if you would have read my previous post than you would have understood that I don't have any problems holding "expect to cross at" altitudes, I am having problem with all altitudes during descent, I don't mean that it can't hold 1 or 2. It can not hold any altitude at all... Manfred

Share this post


Link to post
Share on other sites

I see that now, but based on the fact that my aircraft works just fine, I still think it's a similar issue of not giving the proper information to the FMC. Did you accurately provide your weight to the system? Furthermore, have you run the tutorial to the letter with a positive or negative result? If you're on Vista/Win7, make sure your Config Tool has been given Admin rights. Otherwise, you'll set a particular weight in the config tool, but it won't actually alter the aircraft weight, which could lead to a discrep between your assigned weight and what actually happens in the sim.

Share this post


Link to post
Share on other sites

No I have not done the tutorial but I have flown several other flight by using the tips from the tutorial... It has not to do with the weight system since I am always double checking the "auto entered" ZFW value against the value from the configurator... Shortly said the value entered in the FMC is correct, I can assure you that. Thought there is something that crossed my mind and that that is REX, I had REX before but I removed it since it interfered with the Simcheck A300. Maybe there is still some bug making the MD11 think descend way too late or think that is able to descent in the short distance. I'm almost thinking of doing an full Win 7 reset and check if it works better after... Unless anyone can come up with something better....

Share this post


Link to post
Share on other sites

I just would like to tell anyone having the same problem that only a fresh install, in my case a total computer format helped against the misbehavior of the MD-11. The MD-11 I fly now feels totally different from the previous one I flew and mostly follows the profile from the FMS. Manfred

Share this post


Link to post
Share on other sites

When you have restriction (in the STAR) with at or above altitutes it gives problems. So I change this in the altitute given, then there is no problem. You also have to check if the values are correct in Perf/approach before TOD. When it really doesn't work out, use speedbrakes and cancel profile flight. In real they do it frequently. John

Share this post


Link to post
Share on other sites
When you have restriction (in the STAR) with at or above altitutes it gives problems. So I change this in the altitute given, then there is no problem. You also have to check if the values are correct in Perf/approach before TOD. When it really doesn't work out, use speedbrakes and cancel profile flight. In real they do it frequently. John
Ok, thx for the tip about changing in into the altitude given. Never thought of that one. I always update my values in the entire FMC, (perf/approach/forecast included) but sometimes it still doesn't exactly follow my plan but as you say it may be the "at or above" restrictions. But it is 1000 times better now then before my reinstall. Before that the airplane was never able to follow my descent path. Even when I followed the prof plan the altitude above the path always got higher and higher increasing to 4000+ feet above prof. At least now if I pull the altitude selector the airplane is able to recapture the profile without being in need of spoilers.

Share this post


Link to post
Share on other sites

×
×
  • Create New...