AP vertical mode

[MatzeH84 88]

Hi, I reported this issue some time ago.. the AP often is going mad on the vertical modes. Just did another flight EDFH/EDDL and got it on several occasions.

What happens:

I take off, climb out and trim the aircraft for cruise climb after flap retraction (around 100kts). I preselect 5000ft in the box and engage the AP with ALT ALERT armed so the AP will level out at 5000.

During the climb I adjust the pitch using the default FSX commands, but the necessary actions are mininmal. Reaching 5000 the AP is throwing the plane into a dive, I deselect the AP and get the plane up to 5000 again manually, trim it out properly, make sure no AP mode is active and re-engage the AP. Selecting ALT mode the plane again is pitched down violently. Flying manual again, I climb to FL090 now, re-engaging the AP to hold the pitch, which now works properly. ALT ALERT is not used, upon reaching cruise alt I ease the climb using the pitch command and select ALT, which now works again.

On the descend to EDDL I got clearance to FL060, deselected ALT, set 6000 in the box and brought the plane into descend using the pitch commands again. ALT ALERT is armed. ~300ft before reaching the target altitude, the ALT mode engages automatically and the plane pitches up wildly again. Manually brought it back to FL060,l trimmed it properly, engaged AP, then ALT mode, plane pitches up again.

Somehow got it fixed then. Approached the ILS at 3000ft as published, AP in HDG and ALT mode, set on APR mode, plane pitches up into the sky again.

Any ideas on this? ALT ALERT and MDA do not work at 95% of the times I tried it due to the pitch-up/ pitch down. ALT mode usually works, but in 30% of the cases it doesn't.

Matthias

[Bert Pieke 26]

Quote: "During the climb I adjust the pitch using the default FSX commands"

That is likely the problem... the FSX pitch commands are not the way to adjust

pitch on this autopilot. Try using the Pitch Rocker Switch on the yoke (in the center) instead.

This switch is operated, using the mouse wheel.

Or, you can use IAS mode and use the throttle to adjust pitch.

[Finn 873]

Quote: "During the climb I adjust the pitch using the default FSX commands"

I agree that exactly there You ar doing something that doesn´t work nor should.

You must use either IAS mode or manual vertical mode (Autopilot On, but no vertical mode ie. ALT, IAS or APPR selected)

In IAS mode it will simply keep the speed present when the IAS button was pressed. Rate of climb / descend is controlled with the power lever.

In manual vertical mode pitch angle is set via the rocker switch on the centerpart of the Yoke beside the Yaw damper switch (mousewheel).

Finn

[Tozzifan 7]

Hello,

I'm sorry I'm neither a pilot nor a expert, and searching brought me here, because I had the same difficulties:

please, what's the use then of the functional trim knob, down by the side of pilot chair? (the one which I fought so far )

thanks

[Finn 873]

Hello,

I'm sorry I'm neither a pilot nor a expert, and searching brought me here, because I had the same difficulties:

please, what's the use then of the functional trim knob, down by the side of pilot chair? (the one which I fought so far )

thanks

Please read carefully..

With Autopilot off You steer with Yoke and pedals. Trimming is done with the trim wheels found below the captains armrest on the seat (Hard to see from the captains view - use the panel selector).

If You want to use the autopilot, first trim the aircraft to keep it in the wanted attitude without having to apply any kind of pressure on the yoke - it should literally be able to fly on it´s own more or less without any input.

Now enage the autopilot by turning the switch on.

The autopilot will now be in "Manual" vertical and lateral mode meaning that it will keep the attitude that was present when the autopilot was engaged in both pitch and roll.

In manual mode You can adjust both pitch and roll via the rockerswitches on the center part of the yoke. Left(Right click to adjust desired bank/roll angle and use mousewheel up/down to adjust desired pitch angle.

Pressing any vertical mode like ALT or IAS or mode will now let the autopilot follow the guidance for those while still being in manual lateral mode ie. bank/roll is still controlled via the rockerswitch with left/right click.

Pressing any lateral mode like HDG, NAV or BC will let the autopilot follow guidance for those while still being in manual vertical mode ie. pitch angle is still controlled via the rockerswitch with mousewheel up/down.

Any combination between lateral and vertical modes can selected. APPR mode is used for ILS approaches and when engaged will disable both manual lateral and manual vertical mode.

Manual vertical and lateral mode simply means that roll and pitch can be selected manually via the rockerswitch.

You cannot adjust trim when the autopilt is engaged, since the autopilot also uses trim to control the aircraft. Controlling any axis of the aircraft via the yoke is also not possible when the autopilot is engaged.

But to emphasise !!!

Always trim the aircraft to the desired attitude BEFORE engaging the autopilot. Don't pull back on the yoke inorder to climb and then engage the autopilot - simply trim the aircraft to make it fly at the desired attitude before engaging the autopilot.

I see this issue pop up quite frequently, so better learn to cooperate with the autopilot rather than fight it.

Finn

[GroovyMotion 1]

Thank you Finn this post was one of the most helpful! I too am a still a newbie with the twotter, which is my favorite aircraft!

I have found many interesting things in this forum and I thank you!

[Finn 873]

Don´t hesitate to ask further questions, that is what this forum is for.

Finn