G'Day everyone,I have some problems when landing without AP with the PSS 757. At about 6 or 700 radio altitude, just aligned and fully established on the ILS I disconnect AP and I must to push forward the Saitek X52 PRO controller to bring down the aircraft, if I leave the stick in the null zone, the aircraft increase its pitch and don't follow the glideslope. Sometimes I have to push forward very strong cause I cannot descend. When I begin the ILS autoland there are 2 white PAPI lights on, when I swtich to manual, for the problem described all PAPI lights are white.Is it quite strange for you or not? I don't know if something set up wrong. For example, I trimmed the horizontal stab before take off with the value given by the CDU but I never changed during the rest of the flight. Have I maybe to reset before landing to that value?Thanks bye.RR

I think it maybe the trim not resetting.Have you tried trimming nose down after disconnecting the AP?May also be you are not using a registered FSUIPC and thus the trim on disconnectingAP goes to the full nose up position for whatever reason.

Aircraft can (and do) adjust the trim in automated flight, since the fuel burns off and alters the weight, so your correct take off trim setting is unlikely to be suitable for landing as well (especially since you will have more flaps on landing), nor will be the trim setting the autopilot might have adjusted things to when in the cruise be suitable for the landing configuration, where it wants the minimum of drag for fuel economy in the cruise. Take off trim has to be quite positive in most cases, since you will probably have flaps on take off, and that means the airflow from the wings which then reaches the tailplane will be at a higher angle of attack than would be the case without flaps (since the flaps deflect the airflow downwards), which makes the tailplane more efficient at doing its job (i.e forcing the tail down and pitching the nose up as a result of that).When slowing for an approach but still on autopilot, the autopilot may trim up to increase the angle of attack in order to fly slowly, since when in the descent, you are effectively going 'downhill' and the autopilot has to find some way of controlling the airspeed. Normally, your method to control the descent speed will be the gradual application of flap settings in order to increase the drag (along with lowering the gear too), which ironically will require more thrust even though you want to slow down. As in the take off configuration, it is worth remembering that the autopilot will almost certainly increase pitch trim when you lower the flaps, since lowering the flaps will again cause a pitch down unless trimmed out, and if the autopilot puts a lot of elevator trim on, you may be left with very little control authority on your joystick when you disengage the autopilot (which sounds like what is happening to you).Airliners are odd in the fact that unlike with smaller GA aircraft, where we are taught that you control altitude with the throttle and airspeed with pitch, that isn't always true on big jets, especially during the landing phase, when the reverse is sometimes the case. So you probably will find that you have to use trim, main control inputs and throttle to get the aeroplane pointing where you want it to go. The 757 is something of a 'rocket ship' in real life, with a very high thrust to weight ratio which not surprisingly, will mean that the trim has to work hard, and when you knock the autopilot off, that becomes your job. There are always some compromises to be made when flying a simulated aeroplane with a PC joystick, but if you have a joystick with two thumb buttons, it is a good idea to make the left thumb button adjust elevator trim down, and the right thumb button adjust the elevator trim up, since that is a fairly intuitive and easy to reach method of trimming the aeroplane whilst maintaining control.Al

Aircraft can (and do) adjust the trim in automated flight, since the fuel burns off and alters the weight, so your correct take off trim setting is unlikely to be suitable for landing as well (especially since you will have more flaps on landing), nor will be the trim setting the autopilot might have adjusted things to when in the cruise be suitable for the landing configuration, where it wants the minimum of drag for fuel economy in the cruise. Take off trim has to be quite positive in most cases, since you will probably have flaps on take off, and that means the airflow from the wings which then reaches the tailplane will be at a higher angle of attack than would be the case without flaps (since the flaps deflect the airflow downwards), which makes the tailplane more efficient at doing its job (i.e forcing the tail down and pitching the nose up as a result of that).When slowing for an approach but still on autopilot, the autopilot may trim up to increase the angle of attack in order to fly slowly, since when in the descent, you are effectively going 'downhill' and the autopilot has to find some way of controlling the airspeed. Normally, your method to control the descent speed will be the gradual application of flap settings in order to increase the drag (along with lowering the gear too), which ironically will require more thrust even though you want to slow down. As in the take off configuration, it is worth remembering that the autopilot will almost certainly increase pitch trim when you lower the flaps, since lowering the flaps will again cause a pitch down unless trimmed out, and if the autopilot puts a lot of elevator trim on, you may be left with very little control authority on your joystick when you disengage the autopilot (which sounds like what is happening to you).Airliners are odd in the fact that unlike with smaller GA aircraft, where we are taught that you control altitude with the throttle and airspeed with pitch, that isn't always true on big jets, especially during the landing phase, when the reverse is sometimes the case. So you probably will find that you have to use trim, main control inputs and throttle to get the aeroplane pointing where you want it to go. The 757 is something of a 'rocket ship' in real life, with a very high thrust to weight ratio which not surprisingly, will mean that the trim has to work hard, and when you knock the autopilot off, that becomes your job. There are always some compromises to be made when flying a simulated aeroplane with a PC joystick, but if you have a joystick with two thumb buttons, it is a good idea to make the left thumb button adjust elevator trim down, and the right thumb button adjust the elevator trim up, since that is a fairly intuitive and easy to reach method of trimming the aeroplane whilst maintaining control.Al

That's all fine, except that what the OP is asking about is an actual bug in the PSS 757 as I've seen it as well. The aircraft, after AP disconnection, will continuously try to set full up nose trim, making manual flight very difficult. I think the way to get around this PSS bug is to disconnect the AP via the MCP disengagement bar, instead of the quick disconnect yoke button if you've got that mapped to your joystick.Airliners are not any different against any other aircraft in that pitch still controls speed and power still controls altitude. But since most of our landing approaches are done with reference to a pair of ILS needles, it is easier to follow a glideslope needle with pitch changes to affect the instantaneous VSI while making sure you make a "combined" adjustment on the throttle. In a GA aircraft, you do an ILS the same way, you fly the glide with pitch and speed with power. You do this safely because in a GA aircraft, you will make the approach at a much higher speed (eg 90kts) than you would use as your final approach speed (eg 60kts), thereby keeping yourself on the frontside of the power curve and allowing you to more safely pitch for altitude. In an airliner, with all our high lift devices, even though we are flying the approach at a speed near 1.3Vso, the aircraft still behaves relatively close to being on the frontside of the curve. But once you fall below that approach speed, the backside of the curve will be short, sharp, and unforgiving.This is illustrated well with the MD-11. A development of the DC-10, the MD-11 was built with not enough wing. There have been several landing accidents where the aircraft has landed short, hard and broken up on the runway in a fiery manner. It's landing approach needs to be flown more like that of a GA plane that makes its final approach deep within the backside of the power curve. Any low situation needs to be fixed with power first and foremost. Any slow situation needs to fixed with a push on the yoke first and foremost. Pilots have forgotton this, and tried to fly it like a more forgivingly designed airliner, pitching up into a glideslope above them, or pulling off power to slow down. In an MD-11, the greater effect of these actions while at approach speed would have been to cause an increasing sinkrate and then a demolished aircraft if the pilot fails to make an aggressive addition of power.

Airliners are not any different against any other aircraft in that pitch still controls speed and power still controls altitude.

Yup, and that's why you should note that I wrote: 'we are taught', i.e. in the techniques one should typically use, rather than writing that airliners are any different aerodynamically from any other sort of aircraft, although inertia is of course a factor. In almost fifteen years of real-world piloting I have never once killed myself by messing up a landing, so I'm fairly sure I know how they work LOL.Incidentally the problem with the MD-11 is more about the fact that it originally had too much elevator authority rather than not enough wing area. It was found that this made it possible to actually damage the wing by exerting too much stress upon it, to the extent that one of the MD-11 prototypes actually had its main spar cracked by that phenomenon, so they reduced the area of the tailplane, which solved that problem but then meant that at lower airspeeds there was not enough elevator area to enable the MD-11 to be flown like most other airliners typically are, i.e. with pitch alone controlling the descent after getting into the glideslope pipe.Al