Archived

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

JSACKS

Managing autoland in the PSS 777 in FS9

Recommended Posts

The autoland function does work for me pretty well most of the time with this lovely machine but she lands with a big WHUMP! (usually -400 to -600 fpm) and it seems one must turn off the A/T manually prior to thrust reversing. Is there some non-standard procedure to make autolands smoother and less rushed and violent?Appreciate any posts, thanks!JS

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

bump, also need help with this!
Sure as heck ain't much help out there! Double bump!JS

Share this post


Link to post
Share on other sites

JSIf you do a search of the forum, you will find some detailed discussion on the autoland and the various landing techniques. Also, ask yourself why autoland was developed in the first place and when it is essential that it is used. If you have the LDS, its also interesting to compare the way autoland is programmed in their 767.As to A/T, I haven't flown the 757 for some time so I'll crank it up and have a look later.John R

Share this post


Link to post
Share on other sites

JSReverse thrust works fine here landing with A/T engaged. I have flown two full autolands, and one manual landing with A/T controlling speed. In each case reverse thrust deployed normally when I selected it after touchdown.Let me know what technique you are using an we will see if we can sort it out.John R

Share this post


Link to post
Share on other sites
JSReverse thrust works fine here landing with A/T engaged. I have flown two full autolands, and one manual landing with A/T controlling speed. In each case reverse thrust deployed normally when I selected it after touchdown.Let me know what technique you are using an we will see if we can sort it out.John R
Thanks. I need to repeat things here first to see what is happening and what I am doing and then I shall report back.JS

Share this post


Link to post
Share on other sites

OK, this evening I conducted half a dozen AUTOLANDS into KIAD 1L on the T-7 at 380K lbs. with fine weather and either no x-wind or x-wind of 9 knots. The FMC provided guidance for approach speeds and flap settings which I followed precisely including the vref margin for final approach. All autolands were very firm or hard at around -500fpm because autothrust remained engaged on touchdown. Also,there was no visible flare prior to touchdown even though FLARE was annunciated as armed on the PFD prior to touchdown. The AT kept N1 averaged at about 45% on final approach, rising to 47% on short final to keep speed pinned at Vref+5. All callouts functioned normally as well. At approximately 30' AGL, N1 started to ease back but it did not fall below 41% prior to touchdown. The inability to engage reverse thrust turns out to be a hardware issue with my CH throttle quadrant. It seems that until I turn off A/T manually just before or just touchdown, the reverse position does not function on the quadrant with this aircraft. However I discovered that the age-old F2 key does work right away to engage reverse so I ended up using that. That's an OK fix for me.What remains perplexing is the hard landing. The only fix I can think of is to chop the AP at about 100' AGL and switch off AT off at 50' AGL,ease back manually on my quadrant and try to flare a degree or two at 30' AGL. The current autoland does work (every time) but as I say it slams me down. Is there another fix I am missing?JS

Share this post


Link to post
Share on other sites
OK, this evening I conducted half a dozen AUTOLANDS into KIAD 1L on the T-7 at 380K lbs. with fine weather and either no x-wind or x-wind of 9 knots. The FMC provided guidance for approach speeds and flap settings which I followed precisely including the vref margin for final approach. All autolands were very firm or hard at around -500fpm because autothrust remained engaged on touchdown. Also,there was no visible flare prior to touchdown even though FLARE was annunciated as armed on the PFD prior to touchdown. The AT kept N1 averaged at about 45% on final approach, rising to 47% on short final to keep speed pinned at Vref+5. All callouts functioned normally as well. At approximately 30' AGL, N1 started to ease back but it did not fall below 41% prior to touchdown. The inability to engage reverse thrust turns out to be a hardware issue with my CH throttle quadrant. It seems that until I turn off A/T manually just before or just touchdown, the reverse position does not function on the quadrant with this aircraft. However I discovered that the age-old F2 key does work right away to engage reverse so I ended up using that. That's an OK fix for me.What remains perplexing is the hard landing. The only fix I can think of is to chop the AP at about 100' AGL and switch off AT off at 50' AGL,ease back manually on my quadrant and try to flare a degree or two at 30' AGL. The current autoland does work (every time) but as I say it slams me down. Is there another fix I am missing?JS
I have the same problem. I wanted to fix it myself instead of waiting around for a patch or whatever but I have no idea where to start or if it's even legal. I would think it's in the .air file but I'm not so sure.-Andy

Share this post


Link to post
Share on other sites
I have the same problem. I wanted to fix it myself instead of waiting around for a patch or whatever but I have no idea where to start or if it's even legal. I would think it's in the .air file but I'm not so sure.-Andy
Hey. Andy:Welcome to AVSIM. I See this is your 'maiden post'. Congratulations!!JS

Share this post


Link to post
Share on other sites

PSS was never wont to go too far beyond building around default fs parameters. If it is a problem I tend to think it's more to do with the ap programming than fde. Now that I mention it though aren't there some ini files in the PSS folder (I'm at work)? Maybe the answer lies in some tweak?Some queries thoughDoes landing weight affect this hard autoland tendency? Also, as John intimated above, is not a hard landing normal in conditions so bad they warrant an autoland? A safe landing in such conditions (also assuming contaminated runway) is a firm one in the td zone no? Too, if memory serves, the LDS 767 also autolands rather firmly.

Share this post


Link to post
Share on other sites

Sorry, guys but this is the PSS 777 we're talking about and even though you've got bells and whistles blinking and whirrring away, underneath it all its just pretty much basic a FS9 autopilot beating under it all. With that said, a heavy landing weight doesn't make a difference with the smoothness of an autoland just like it doesn't make a difference with a non-automated landing. Vref airspeeds will be higher as you go higher in weight but that doesn't mean that the aircraft should drop to the runway.The problem is not with weights, its with the PSS autopilot exhibiting behavior that were known to PSS but were never fixed before they went out of business. Aircraft like the LDS 767 and PMDG fleet have higly customized autopilots that go outside the guidelines of the basic FS9 aircraft SDK which allows to overcome these issues.BUT, in the same token, autolands and NOT going to be greasers! Autopilot landings are programmed to consistantly put the aircraft in the TDZ, firmly. Don't expect greasers on autoland, because its not concerned with confort as much as it is concerned with getting the aircraft to the runway in 0/0 visability. The need to disconnect the autothrottle manually IS a bug however.HTH!

Share this post


Link to post
Share on other sites
Sorry, guys but this is the PSS 777 we're talking about and even though you've got bells and whistles blinking and whirrring away, underneath it all its just pretty much basic a FS9 autopilot beating under it all. With that said, a heavy landing weight doesn't make a difference with the smoothness of an autoland just like it doesn't make a difference with a non-automated landing. Vref airspeeds will be higher as you go higher in weight but that doesn't mean that the aircraft should drop to the runway.The problem is not with weights, its with the PSS autopilot exhibiting behavior that were known to PSS but were never fixed before they went out of business. Aircraft like the LDS 767 and PMDG fleet have higly customized autopilots that go outside the guidelines of the basic FS9 aircraft SDK which allows to overcome these issues.BUT, in the same token, autolands and NOT going to be greasers! Autopilot landings are programmed to consistantly put the aircraft in the TDZ, firmly. Don't expect greasers on autoland, because its not concerned with confort as much as it is concerned with getting the aircraft to the runway in 0/0 visability. The need to disconnect the autothrottle manually IS a bug however.HTH!
OK, Mike (and Greetings to you!), so it's good to know that this is simply a limitation of the autopilot system. If nothing can be done about it in terfms of the automation, then nothing can be done.The Level-D and PMDG autolands are miraculously smooth, usually around -100 or -150 fpm. I guess that would be termed mildly firm but a great deal smoother than PSS. It's a shame PSS was unable to engineer the AT to cut properly and pull back to near idle, as well as flare a tad, for touchdown because it would have made a big diff to the smoothness of the touchdown.Guess one can't have everything. Anyway, for me personally the PSS does fly very well and a lot better and without any of the glitches many have reported. I got the CD ROM edition and did an update or two and she is a good bird in all other respects.JS

Share this post


Link to post
Share on other sites

Folks,This was discussed ad infinitum a couple of years ago on this forum and I totally agree with Mike's analysis on what is required from an autoland system in real life - we certainly do not want greasers!As to the simulations, it is a pity that PSS never went the extra mile with the AP {along with lots of other things!} but both 777 and 757 do at least give a consistent TD point at the right speed. Both aircraft flare but perhaps too little and too late! If you watch, rod is reducing and demanded N1 is reduced to idle from the start of the flare. Also I always get reverse thrust - either from a button on my Saitek system or by the FDC FO - without disengaging auto-throttle.Of interest, when I started with the 767, I noticed that the LDS programming seemed less consistent. At heavy weights it is similar to the PSS result {with a better rod at touchdown} but at light weights it tends to float and you can find yourself touching down up to a third up the runway. One reason why I always take over for a manual landing when onVATSIM.Perhaps if PSS ever re-appear {!!!} these AP tweaks could be a part of the FSX updates ......John R

Share this post


Link to post
Share on other sites

Hi, FOD:You are correct in all you say. I am not complaining, I am actually delighted that autoland works at all in the PSS bird. I was just fishing for an informal fix but it's not a big deal; the fix is to accept the landing as it comes and then hit F2 right away. Or, if not, then disconnect AT and AP at 100 AGL and hand fly the flare and N1 spool down.I admit I am two years behind with this bird in particular because I waited for a CD-ROM and also I did not wish to experience the many tech issues that plagued the initial release. I am normally not 2 years behind the curve in FS (although I might be way behind by the time the CD-ROM for PMDG MD-11 for FS2004 is released!).JS

Share this post


Link to post
Share on other sites

JS," (although I might be way behind by the time the CD-ROM for PMDG MD-11 for FS2004 is released!)."Know how you feel - I am waiting for the MD11 to mature for FSX let alone for FS9.As to the 777, I have just reminded myself that it was first released in Autumn 05 {and that was a mess} but it still goes strong looking at the post we get on this forum.John

Share this post


Link to post
Share on other sites
JS," (although I might be way behind by the time the CD-ROM for PMDG MD-11 for FS2004 is released!)."Know how you feel - I am waiting for the MD11 to mature for FSX let alone for FS9.As to the 777, I have just reminded myself that it was first released in Autumn 05 {and that was a mess} but it still goes strong looking at the post we get on this forum.John
Yeah, various of our favorite commercial add-on aircraft that were released as much as 5 years ago remain hugely popular to new users in FS9 and FSX. It's really amazing. Great hobby, eh?JS

Share this post


Link to post
Share on other sites