pilotresponse

Got an answer to the technical ticket I raised with PMDG "It is a known issue with the simulator Ground Friction model and the aircraft that is currently under investigation. We hope to have a solution in a future update."

Thanks for your comments, will do. I am asking if any other PMDG 777 users have experienced this manual landing behaviour

Those limits are from the PMDG provided FCOM, AFM information and my FCOM says different in fact on dry runway company limitation is 45kts (real world). Yes you are right pilots should have their own limitations. I've also done it close to that in real world and agree, since all sims (from PC to big training ones) don't really do it justice. The problem is with your comment on the limits of the envelope and that "no PC simulator does well at the limits", as I said I have the PMDG 744,748 and QW 787 and was able to land all in the same conditions without the strange aircraft behaviors I saw in the 777. I will provide a video shortly to show you how strange this is. I am trying to see if as you say it is an inherent limitation in the 777 PMDG product and if so why? thanks for your comments anyway, I am hoping to get that data.

What crosswind limitation are you referring to? 777 doesn't have a crosswind limitation that I know of, just a maximum demonstrated component of 42 knots but the real sims can be set to up to 55 knots. Autoland limit is 25kts, but the PMDG 777 will still do the autoland more or less perfectly even in 35kts plus, it's only in manual flight that this strange behavior shows up. Any thoughts?

I will try to post one but if anyone has P3DV4 and can try flying to any airport that can accommodate a 777, (add on or not, doesn't make a difference) and modifies wx to a steady 35kt crosswind or greater and attempts a manual landing you should see the same strange behavior. Or at least the 3 of us did for sure. Really unrealistic behavior, at this extreme end of the envelope, are we all missing something?

I was wondering if anyone has had and issue with the 777 manual landings in crosswinds in excess of 30kts. In all tests I have done and confirming this with at least 2 other friends of mine who also have the 777, we have all found it impossible to land the 777 manually with winds of 35, 40, and 45 knots full crosswind, even though in autoland the aircraft manages to land. The behavior of the 777 has been the same for all of us. The aircraft lands at first but will not decelerate with spoilers armed, and reversers deployed. for all of us EICAS does not show reversers green, eventually wind vector on the EADI shows headwind even though sim says constant crosswind (displayed in red with shift Z) and airspeed suddenly increases by 10-20 knots and 777 becomes airborne again. The 3 of us have different control yokes, rudder pedals, and throttle setups, but experienced the same thing. Other sim aircraft we try do not experience this problem including pmdg 744,748 QW787 and others. Are we all missing something or is this a PMDG 777 issue. Should I open a technical ticket with PMDG as to this strange behavior on P3DV4?

Hi Bryan I'm having the same issue doesn't want to recognize my vref call and can't continue with the descent checklist, tried to train my voice software some more but didn't help? any thoughts?

I agree with 777 simmer, maybe the issue is that past 80kts when the FMA annunciates HOLD the throttles will reposition themselves to where you have set them, if it was full forward then you will see the thrust go right to the stops, as the AT servos are disconnected at this point and maybe unknowingly you are commanding full thrust all the time, even though you have set a DE-RATE or ASSUMED temp. Furthermore, you might want to try a lower flap setting, flap 5 should suffice for most take-offs and the climb angle is shallower. Also make use of the FPV or flight path vector during take-off it is very useful, especially if you are at light weights and high thrust settings. Use the FPV and anticipate your level off altitude, remember level off should commence at a rate of approx 100ft per 1000ft of vertical speed. If your climb rate is 2000ft/min you should start your level off at least 200ft before reaching your desired altitude. Since in normal ops the 777 is always flown with the A/T on, your A/T FMA should annunciate SPD when you are at your level off altitude.If you are in THR REF or THR mode the aircraft will keep accelerating. If you are in HOLD mode and your thrust lever is set full forward you will keep accelerating so check your settings and please try again. When you level off your vertical mode FMA should annunciate VNAV PATH, VNAV ALT or ALT. In real life the 200LR is also a real hand full taking off, our golden rule is to pitch towards 15 degrees nose up and then adjust our speed to maintain V2+15 to V2+25. A proper rotation rate will leave you at V2+15 to V2+25 every time! cheers, Karl

that's within reason, but I haven't noticed a tendency for the airplane in the sim to float, or the A/T to do strange things on landing, pretty much behaves as in real life to me. Enough said. enjoy K

Martin, I find it works pretty true to life, again I think that PMDG has done a great job considering this is a desktop simulation. In the real aircraft an autoland does eat up about 400 to 500 meters of runway, which is what I'd say it's doing in FSX, but can't really tell, it's close enough in my opinion. The A/T BEGINS to move to idle at 25ft RA and should ideally reach idle at the same time the wheels touch. So says the book. When the A/T is off (and for a reason which has never been explained to me, and which I disagree with and don't understand, at my airline we fly ALWAYS ALWAYS with the A/T engaged and are not allowed to disengage it, unless it is failed or malfunctioning.) thrust reduction should be timed just after initiating your flare, while holding a constant pitch with back pressure on the column making only small pitch changes to adjust your rate, and again idle should be reached as the wheels touch. I find that it's quite well simulated and I'm happy with it. Though you are right about the spool down, being a somewhat lethargic, as is spool up I find, but I'll let you know for sure in the next month as I fly the sim more often. regards, K

Eric just as a note in the real aircraft, at light weights, it is a handful to land and the flare must be more agressive as the CG is much farther forward and stab position is less affected by the elevator making it more difficult to fly the 777 on to the runway, which is what boeing want you to do. You should never hold the airplane off, as you do on light airplanes (risking tail strike or causing a porpoising bounce), if you have flared to early just hold the attitude you have and add power to arrest your descent rate. If you flare early and then lower the nose to correct you are risking putting an enormous lifting surface back into ground effect (the wing) and this will extend your landing distance considerably. Instead keep your attitude constant and use power if you have to arrest rate, the induced drag being produced by that big wing and flaps will simply fly airplane to the ground. (unless you really flared early in which case a go around is the only recommendation) Late Flares always lead to bounces, if it's a shallow bounce hold what you have and again arrest rate with power if necessary always mindful of how much pavement you still have ahead, if its a deep bounce a go around is the only answer! just remember though to follow through your selection of TOGA as the auto throttle may have not function as you would expect. When the 777 200LR is heavy she is very docile in landing and much less flare is required, by judging your flare point according to the FCTM, she seems to come down more gently, though now stopping distance is really an issue, so as I said you should never make a smooth landing a must, its desirable but as I said not necessary. As was said before in this forum, spoilers are key to stopping, reverse thrust adds little to stopping distance especially on dry runways, but can make a huge difference in the brake energy required to do so. One last thing, a damp or slightly wet runway are a pilot's favorite as smooth touchdowns are almost always generated, though I'm sure those of you excellent flight sim enthusiasts know why, something to do with friction and momentum I'm sure. For me and all other pros "greasers" are always a treat rather then an objective. cheers, K

When you fly the real aircraft flare height is a funtion of sink rate, not just a number. If you listen out for altitude auto call outs with a tailwind component, or an upsloping runway you will have a bad day. Incredibly enough when to flare in the 777 is much like the same seat of your pants gut feeling that I got when I flew a Cessna 172 around, it simply feels right. The way to land a 777 is just as boeing recommends in the FTCM, but we don't forget the basics, which they do not mention because they expect you already come equipped to fly the aircraft with that knowledge. In my personal experience on the "200" variants the "20" callout helps you judge the point, in the "300's" 30 feet is better, but I never flare solely based on this. Smooth landings are always desirable, but not necessary. As was mentioned, you must look at the terrifying physics of how much inertia something weighing over 200 tons has. That is why a "firm" touchdown followed by rapidlly selecting reverser and making absolutely sure the spoilers are out is sometimes so important. Happy flying :-) K

Cowl, I'm sorry if you think that there is a contradiction between what I and 777simmer are saying. I don't see it as a contradiction, but more a difference of opinion on how true to the "spirit" of the boeing FBW system the PMDG777 simulates. I have done the experiments 777simmer has done in the sim, and he is correct about how the simulation behaves, in that there is almost an auto trimming effect if you continue to apply column pressure as the plane accelerates or decclerates to the desired speed. which is strange because the trim position indicator does not move. I have noticed also that even when the trim button is pressed the trim indicator barely moves and sometimes doesn't move at all. What I am saying is that even though this is NOT TRUE to the aircraft, this is the way FBW is modelled in the FSX simulation platform. To me this makes this difference not so important so far as I would think it very hard to replicate on this scale the control forces you need to exert in real life on the aircraft, and how a true trim system behaves. Yesterday on a real flight on a 777-300ER I hand flew a departure from an airport in Europe accelarating from flap up speed to 250kts while in the climb, the force I needed to keep the control column down was quite strong, I would compare it to having the CH column pushed in at least 3/4 of travel (and that's understating it). I did this until I grew tired of pushing and and decided to trim. only then did the force needed subside, and I continued to climb to an altitude below 10000ft, at which point I selected the A/P. So as far as I see things, the essence of the way the system should work is simulated, and my tests and yours with the sim prove this, however all of us as flight sim fans should appreciate that the way FSX simulates hand flying, especially of large commercial aircraft, is limited. I'm not saying its poor, just limited. I hope 777simmer agrees, and maybe I was over zealous in expressing my opinion and apologize to him if that was the case, as obviously the modelling is not true to life, even if it is true to the essense that of the aircraft system. I apologize to you also if it caused you confusion. kind regards, K

Last response 777 simmer because your tone is getting increasingly less polite for some reason. I've done " your experiment" and yes the aircraft stays pretty much in trim, the reason which I explained in my last response. It is meant to stay in trim because you are applying a force on the yoke, the FBW is sending a signal to the flight control surfaces that you wish to maintain this attitude and they are responding to minimize forces required to do so, when you reach the new speed you release the yoke, and magically the aircraft is in trim, correct? Yes it is, and no further trimming required because at that moment you are not changing speed, or making an input of the control column. If you were to make a speed change WITHOUT an input to the yoke the aircraft will not trim, understood? That is how the system functions in the real aircraft period. How this proves to you that the FBW is not simulated properly comes from your misunderstanding of how the system functions, I will not post another reply to you, and sorry you're dissapointed with PMDG's simulation of this I AM NOT and think they have modelled th FBW very well considering this a product for FSX.

777simmer and other friends, my experience is exactly as the FCTM says, that the FBW system "minimizes the airplane pitch response to thrust changes, configuration changes" I think minimizes is the key word here, it's not intended to take all the response out, but to minimize. Here is the confusion you may have. Thrust changes do not mean speed changes. As in the real airplane when you add or decrease thrust at a constant speed, you must apply control column pressure to maintain attitude, but you will notice minimal change in trim. For example, If you apply pressure on the control column to hold a level attitude, as you add and take away thrust the FBW system will help you in maintaining a constant attitude as advertised and minimizes pitch changes, minimizing change in trim. Once you reach a new target speed you are no longer adding thrust or removing it, that is why your attitude remains constant and the FBW helped you achieve this with minimum pitch change as you held the yoke at constant pressure. Now you are at your new speed, and are NOT changing speed, so this is not an out of trim condition for the FBW. You are instead flying a constant speed (albeit a new one) and the FBW worked as advertised by helping you as you applied pressure on the column to get there with a minimum pitch response, and you are in trim. Now, on the other hand if you let go of the control column in level flight and accelerate the aircraft, thereby changing thrust and speed the FBW will try to MINIMIZE the impact of the trust change which would otherwise cause a large pitch up moment. You are not helping now so there is only so much it can do, and it will not assist in trimming the A/C AS IT CHANGES SPEED, thereby you will notice the aircraft pitch up and stay up as the aircraft losses trim. A telling statement in the FCTM reveals why the system is designed this way, it states "The pilot still needs to trim for speed changes. Column forces increase when out of trim to provide the conventional speed error cue." The dumbed down FBW is a safety feature which helps pilots be aware they are speeding up or slowing down by feel even if they haven't noticed it by sight! How cool is that, Cheers, K