ILS 737 landing goes horribly wrong

[ali]

Hi
I have extensively used fs98 and fs2004 and have done many ils landings correctly.
My friend who installed fsx had problems landing the 737. When i tried i also observed that the plane approaches the runway allright but when i disengage the approach hold moments before i land the plane just shoots up and stalls.
The same happens when i do it at about 1000 ft. Disengaging the autopilot also has the same effect.
If i do not do anything and just land with autopilot ON and approach hold ON the plane touches and immediately takes off almost vertically.
AT is ON, spoilers are armed, they deploy but plane does not land.
We tried landing several times but may be 1 out of about 10 times we could land the plane well,
Can anyone help me with a solution and can say why this could be happening.
Thanks
Ali

[jwenting]

turn off autothrottle as well. Most likely you're coming in way too fast.

AP off at 1000ft, at 2-300ft bring throttles to (near) idle and turn off AT.

Same thing goes for FS2004 and earlier as well btw.

[That Guy]

This is interesting. Great suggestions jwenting, but I find it interesting that they never had a problem until now which shows they were following proper ILS landing proceedures previously.

I'm really trying to think of more suggestions, but you covered what is the most obvious. I will keep an eye on this thread for future knowledge.

[ReggieF5421]

Also take a look at the elevator trim. If you are too slow, the plane is trimmed very high nose up.

As Jeroen notes turning off AP does not turn off autothrottle. If you are turning off the autothrottle separately from turning off the AP - what position are your throttles in when you turn off the AT.

It's very easy to leave them in takeoff/ climb position and forget that will cause almost full power to be applied when you turn off AT.

Are you flying with a keyboard, a joystick (which one) or a yoke (which one)?

[That Guy]

Also take a look at the elevator trim. If you are too slow, the plane is trimmed very high nose up.

I thought of that too, but if he is in auto-pilot the trim has already been set in flight by the computer. Unless there is some bug that reverts it back to a previous setting before the AP was engaged.

Food for thought.

[jwenting]

the trim has bee set, but when you turn off the AP it will stay put where it was which may well be set for a nose-high attitude in order to provide low speed stability.
If he then also turns off AT while having the throttle levers set full forward, the additional thrust WILL cause a rapid climb.

[ali]

Hi all
Thank you guys for the replies.
I will now detail you some more points
We have made several attempts and have come across the following;

The speed that we are coming in to land is between 145 - 160. We tried faster also but same results. We tried coming over the glidescope and just right on it and also sligjhtly below it with same results.
Power i,.e engines are set to about 50-55 %
We fly using the keyboard.

We tried to cut off power to idle immediately on reaching the runway just before touchdown and also immediately on touchdown with AT OFF and ON but till the hind wheels touch it appears to be a perfect landing but immediately thereafter the nose goes up even if the power it idle and spoilers deployed.


1. At 1000 ft if i switch off AP with AT on the plane goes up suddently and it becomes difficult to control it

2. Turning off AT and Flight Director does not have any problem on the approach till it lands or till i switch off AP

3. One more thing, this flight had problems taking off as during take off itself it was immediately going nose high. My friend said that he had to switch to autopilot ON with climb rate set to 2000 to smoothly take off.

4. One more observation, if we disconnect the altitude hold at any point before engaging Approach hold the plane's nose goes up.

I agree that it could be the trim problem but then the plane flew for the next 2 hours after take off smoothly till it landed.

We finally tried to land with autopilot OFF well before aligning with the glidescope and we could land the plane although not properly onthe centreline and a little ahead on the runway but the landing was otherwise smooth.

I think thereis some problem with trim as someone had mentioned but how to keep it right and still engage the autopilot.

Please help with your suggesstions as we are going mad over this landing.

Thanks in advance

[That Guy]

I'm stumped! I can't think of anything to help. Maybe today something will pop into my head. Hopefully the members will be more of a help.

[sirbruchie]

I am gointo to make a couple of assumtions. First of all I am assuming that you are using the default 737 and panel. The only thing I saw mentioned was 737 thus my assumtion. If you are not talking about the default it could be anything such as a faulty cfg file or air file (which could still be the case I suppose if somthing was currupted during installation). All that aside here is somthing you might want to look into. I noticed you said you were flying with the keyboard. Unlike a joystick the keyboard does not automatically center when you let go. It is possible to do what I would call "cross trimming" with the keyboard and not know it. For example: you are getting ready to take off and so you apply back preasure on the stick - with the keyboard you could be applying 1, 2, or 10 clicks. (even more if you are holding down the button). When the plane reaches take off speed it begins to point upward until the bleading off of speed doesn't allow it anymore. Instead of applying foward preasure you correct it with trim you will be "cross trimming". Typically when you take off you trim for climb and use the back preasure to get the plane to the correct angle and then relax the preasure. If trimmed correctly then the plane stays at the desired climb angle.

Back to the problem. If the pilot is rotating and then imediatly engages the autopilot the back preasure on the stick stays in the rotating position (the keyboard does not relax) but the autopilot compensates. As long as the autopilot stays on it is compensating for the exsesive back preasure. (in real life you arms would get tired in about 2 min.) If on short final the you disengage the autopilot for the first time since take off nothing is compensating for the extra back preasure you applied on take off. Thus your abrupt climb and potential stall. Back in the day I used to fly with the keyboard I would sometimes do somthing similar. The difference is there used to be a little gauge that indicated how much back preasure you were applying (back when keyboard flying was probably the norm) because that no longer exists, at least on the main panel, when using the keyboard you have no way of knowing how much back preasure you are actually applying (in this case enough to establish an agressive climb ange after take off). I hope I have not rambled on too much. Then again I could be wrong but this just might be your problem. Just as a thought a $10 or $15 joystick is better than the keyboard any day.

[ReggieF5421]

this flight had problems taking off as during take off itself it was immediately going nose high

This sounds like a serious trim or weight/balance issue.

EDIT - cross posts with the gentleman above - he obviously knows a lot more about keyboard flying than I do.

Some excellent items which I never heard before.

I never could fly with just a keyboard.