Hi,
Please check this video for a P3D product, I matched the operation of the real world system fairly accurately - as did Leonardo.
https://www.youtube.com/watch?v=MJAyLiDE7xUBiggest thing to note is that the autothrottle and autopilot are NOT coupled. They "inform" each other what they are doing and that's it.
For example, the IAS/MACH pitch mode does not use the autothrottle speed knob, it uses the speed selection which will appear in the Vertical speed window, S for speed, M for mach.
Here's some basic write-up I did for another pilot,
The MD-80 does not have a smart climb thrust/idle clamp mode for climbs/descends like the MD-11. The MD-80, pulling the alt knob, simply arms altitude. You need to use another pitch mode to climb/descend. Commonly used is the "IAS/MACH" pitch mode. (not the buttons near the autothrottle controls, this button is near the VERT SPEED and ALT HLD buttons). This uses the aircrafts pitch to keep airspeed. You'll notice on engaging that the autothrust goes into "CLMP" which means its pilot controlled. So, you push IAS/MACH (a second push switches between the 2), and you'll see the current speed pop up where the vertical speed readout is (or in the dedicated area of the dialog). That is the speed target for this mode, keep in mind its not linked to the autothrottle speed/mach mode. Then, in a climb, you push EPR LIM which will set the power to the thrust limit (CL usually) and the aircraft will pitch up to keep the set speed. For descents, simply pull the power levers to near idle (about 0.9-1.0 EPR is used usually) and the aircraft will pitch down to keep the set speed. There is no automatic throttle retard like the MD-11 has, except for landing. Please let me know if you need a video demo of how to use this.
At least 1000ft above the runway, you may accelerate. Usually this is done in the IAS/MACH mode from above. If you are in the TAK OFF MODE (which you should be, if not, push the TO/GA buttons before taking off!), you climb at V2+10 in that mode, then above 1000ft, you select the CL button on the TRI for climb thrust, then press IAS/MACH. Then you can rotate the pitch wheel so it shows 250kts on the AUTOPILOT's speed select, and the aircraft will pitch down to accelerate. Retract the flaps and slats as you accelerate so that you are clean wing by 210kts. After 10000ft you can accelerate to usually anywhere 280-300kts by rotating the wheel. I usually change to mach once the mach I want has been reached. If I want to use mach 0.78 (typical cruise speed), then i wait until 0.78 is shown on the mach indicator, then switch by pushing the IAS/MACH or MACH SEL buttons depending on which system i am using
The MD-88 on github is NOT very similar to this one - only uses similar visuals (both based off Buck's 81). This plane is ENTIRELY REWRITTEN and WIP. Manual start does not work yet, the plane is still in very early development. (But this one is already far more realistic!)
Kind Regards,
Josh