Auto throttle issue

[FlyingBlue]

I have a autothrottle issue with PSX, maybe someone can help me out.
I have this fabulous though excellent program since a week, and have experience with the FSX Ifly B744, with an flawless operating autotrust.
For a manual landing in PSX I disconnect the autopilot at decision height...let's say 200 feet agl.
The autothrottle is untouched, in my opinion the autothrottle should go to idle at around 30 feet.
This is not what is going to happen, instead of idle goes the throttle up to 80%, which is causing switching off the autobrakes, even when the plane is touching the ground with the main gear....the power doesn't retard.
No go around! Powersetting 'hangs' and varies from 80-60% n1....not enough for go around, but instead of landing is the plane is rushing trough the end of runway.
What do I wrong? My only option is autoland and works fine, or disconnect  A/T at decision height and kill the power between 30-10 feet.
Or go for complete manual trust...which is not the way it should be.
I have tried to disconnect my saitek X55 throttle, with no change at all. I have tried anything already.

[Magoo]

Hi FlyingBlue, 

We are discussing that very same topic here

http://aerowinx.com/board/index.php?topic=3532.0

[FlyingBlue]

Hi Mr. Magoo....yes thank you I follow the discussion already with interest.

[John H Watson]

and have experience with the FSX Ifly B744, with a flawless operating autothrust.

There are also discussions on another forum with many disagreements between pilots and engineers on what is correct. I can almost guarantee that iFly is not flawless. Even my Boeing-sourced technical manuals have been incorrect in some respects.

[Blake H]

Yes I have noticed the power up in the flair. Which you instinctively disconnect.

The Fokker 100 lands with the A\T(ATS) on with IAS mode. The power goes to idle(RET) on landing with AP disconnected.

I would have though the jumbo would do the same. 

[emerydc8]

John is right -- it is disturbing how many opposing statements are made on another forum by pilots who are currently flying the airplane. A big problem (aside from Boeing's apparent inability to write manuals) is that you either never do that in the real airplane or, if you do, you don't remember exactly what the FMA or A/T was doing at that point because it was either close enough to what you would have expected (it got the job done) or you were looking somewhere else when it happened. I think it's safe to say, though, that there is no better sim program that matches the actual airplane than PSX; and with every revision, even the small nuances that 99% of the pilots don't even know about are included.

[Blake H]

Another example is in the FCTM it should say smoothly flair to 3-4 up if you pop it to 4 degrees up you will get a nasty float down the runway. I wonder how many guys have read that then tried it on there next flight, because it doesn't discriminate the rate of attitude change. 

[emerydc8]

I'm not good enough to look at the PFD during the flare. Maybe the Boeing test pilots are. I think someone else here mentioned this too, but I listen for the height callouts and how fast they are coming, especially from 50' on down.

[Blake H]

Try cat III landing manual no auto throttle set around 1.20 EPR 270 tonnes.

Just hold 2 degrees all the way down the glideslope then 30 feet chop power. Just prior to the mains touching flair smoothly to 4 degrees. The green moving runway helps and don't make banks changes more then 3 degrees and maintain heading correction within the heading bug. 1 degree pitch up or down to recapture the glide-path. 

Great fun. I show this technique to other pilots to emphases the importance of the pitch + power = performance. 

[emerydc8]

I'll try this in the sim. I'm using the CF6 engines. At 2 (2.5) degrees to maintain the glideslope, I'll presume you are at flaps 30. In the real plane, at 270K, if you chop the power at 30' and wait until the mains touch down before flaring, I think they would probably have to revise the Jeppesen plate to reflect the new lower touchdown elevation. The rising runway may help to flare prior to touchdown, but I think the frequency of the RA callouts is still the best tool whether VFR or W0X0F.

I'm curious what kind of rate of descent are you getting at touchdown when you do this?

[Blake H]

Yes flap 30 or 2.5 flap 25

approximately 300fpm the ground effect slows the rate down rapidly.

Try in aerowinx - if you are say 4 degrees pitch at 15-20ft you will get massive float.

I would say 4 degrees is just on the point of touchdown or just after. very slow rate of change. It should be intuitive you shouldn't drill it in or float you are monitoring the rate of descent.

[emerydc8]

Wow. That's a lot of ground effect. The faster you reduce power the better you have to be at judging the flare and arresting the significant sink rate caused by the immediate loss of thrust, especially when heavy at flaps 30.  Maybe others can comment, but I don't think ground effect is going to cushion it enough to allow you to chop the power in this situation and not flare until the mains touch down. I definitely wouldn't want to try that in the real airplane.

[Blake H]

I didn't either. But it is massive. Only other aircraft I can personally relate this too, is a Fokker 50.  A 50 seater commuter turboprop with a 30 meter wing span. Look at Britjet's training video 'Landing'.  Maybe that will convince you.

[emerydc8]

I don't think Peter's video advocated chopping the power at 30' and waiting until the mains touched down before flaring. In fact, he said if you didn't start the flare at 30' you would "bury it" and I agree with that.

[Hardy Heinlin]

The ground effect in PSX agrees exactly with the ground effect in the BA 744 sim (tested hands off, perfectly trimmed, with video analysis). It doesn't start at 300. It starts below 200 and is very subtle. If your aircraft is not trimmed and you're pulling and pushing on the yoke, you will not notice the effect because your work on the yoke or your mistrimmed pitch drift will destract you from feeling the ground effect.

Blake, at what pitch rate do you rotate at VR? 10° per second? You'll probably get a tailstrike.

Smooth means ca. 2° per second.

Just do the same for the flare. It's just 1 or 2 seconds to touchdown when the A/T goes to idle.

[emerydc8]

Thanks, Hardy. I think the ground effect of PSX is just right. I just don't believe you could start a flare at touchdown, or even 10' or 20 for that matter,' without pranging it on, regardless of ground effect.

[Blake H]

I think the ground effect is just right too.

Rotate rate at take-off standard 2.5-3 degrees a sec

you definitely can start the flare at 30 feet on landing and smoothly work up to 4 degrees on the touchdown or just, I mean just after the touchdown. You can see britjet's video. 

Its subjective its intuitive. Ground effect is enough to prevent a hard landing if you barely change the rate of attitude.

And yes hardy that what I say in the post above smoothly.

[Hardy Heinlin]

Rotate rate at take-off standard 2.5-3 degrees a sec

I've learned it should rather be 2.0° to 2.5° per sec.

[Blake H]

Interesting 

If I sense a engine out in a sim check on take-off is coming. I will intuitively rotate 2-2.5 degrees a second. Sure helps in V1 and VR cuts. Extra energy is always good and less swing! Unless the end is coming up fast. 



Thanks

[emerydc8]

Its subjective its intuitive. Ground effect is enough to prevent a hard landing if you barely change the rate of attitude.

If only that were true in real life.