On 7/1/2025 at 9:36 PM, Schermvlieger said:

My second question is: how to efficiently manage climb and descent using A/S, ALT and TRIM functions in conjunction with throttle management?

First, I'd like to clarify a point that may be important: When you say "TRIM", do you mean the elevator trim (the large wheels on either side of the throttle quadrant), or do you mean the small pitch wheel on the autopilot panel? The latter is the key to smooth climbs and descents.

On 7/1/2025 at 9:36 PM, Schermvlieger said:

Since there is no "Flight Level Change" function where you can simply dial in a climb speed and (optionally) have the luxury of capturing the desired altitude automatically resulting in the plane leveling off; I end up sometimes needing to use "ALT + Throttle back" to reduce the airspeed, then wait until the plane slowed down to the ideal climb speed, and then to resume my climb using "A/S + Throttle up".

So it sounds as if you're asking how to do smooth airspeed changes in a climb?

Let's assume you have climb power set at 14,200 rpm and A/S mode engaged on the autopilot, but instead of the standard climb airspeed of 138 knots, you're climbing at say 160 knots.

There's a key technique here that I suspect you may not be aware of: When A/S mode is engaged, you can press the A/S button again to "cancel" A/S mode. The vertical mode of the autopilot will in then revert back to a pitch mode, which will hold whatever pitch you had when A/S mode was canceled. You can now change the pitch the autopilot is holding by turning the autopilot pitch wheel. Turn the pitch wheel in the "up" direction to increase pitch slightly, which will cause airspeed to decrease. When the airspeed has reached the desired value (in this case 138 knots), press the A/S button to re-engage A/S mode. (Instead of pressing the A/S button to cancel A/S mode, you can also just start turning the pitch wheel, which will then cause A/S mode to be canceled and the A/S button to pop back out.)

On 7/1/2025 at 9:36 PM, Schermvlieger said:

Conversely, when I am working on the descent to destination airfield, I have some problem managing my descent rate when I use the A/S function of the autopilot in conjunction with Throttle down. So instead I tried to use the trim function, but the problem with the trim function is that it disables the VOR.APP 

Again, by "trim function", do you mean the autopilot pitch wheel? Turning that should not cancel VOR tracking. (If you're already on the ILS at this point, then I assume that turning the pitch wheel will cancel glideslope tracking, and maybe that cancels VOR-APP mode outright.)

But in any case, if you're satisfied with your speed and all you want to do is adjust your descent rate, I'd like to suggest a different technique: Stay in A/S mode and use the throttles to adjust descent rate. If your descent rate is too high, add power. The autopilot will have to pitch up to maintain airspeed, and your descent rate will decrease. Conversely, if your descent rate is too low, reduce power, and the autopilot will have to pitch down to maintain airspeed.

If, on the other hand, you want to change your airspeed in the descent, use the same technique I described for climbs above. If your speed is too high, turn the autopilot pitch wheel in the "up" direction to increase pitch (canceling A/S mode and putting you into pitch mode); once you've reached the desired airspeed, re-engage A/S mode. Conversely, if your speed is too low, turn the pitch wheel in the "down" direction, then re-engage A/S once you've reached the desired airspeed.

It takes a bit of getting used to, but you can fly climbs and descents very smoothly with a bit of practice, and there's a certain satisfaction from being a bit more hands-on with the process.

Again, let me know if there's anything that's unclear.

Martin thank you very much for helping me getting to grips using these AP functions by sharing your experience and tips in such a clear and complete manner! I was indeed talking about the little pitch wheel that is part of the AP system. With regards to the pitch wheel disengaging the VOR.APP; I must be confused about that; I'll be bringing your tips into practice next time I take the old lady for a spin!

Thanks again,

Scherm

Just spotted this, surely it may of interest to someone in this thread ?

 

That (the British Midland F27 technical manual) is the kind of thing that needs to be scanned in/ digitized and otherwise saved.  

In a few decades none will exist, and no possibility of re-creating it.