Can someone who knows please chime in...

 

When you are at cruise altitude with AP ALT hold, when you dial in a new, lower altitude the plane instantly starts a 1,500 FPM descent. Wouldn't proper behavior be - select new altitude, press DESC, then the descent begins? Also, this happens whether you are in ALT mode or ALT SEL. Surely it is incorrect if your are in ALT mode. It should just hold your current altitude without regard to the Altitude Selector, right?

I have posted in a few threads about the AP, Im having alot of issues, I have to stay in ALT SEL all the time or my plane does a dive bomb if II select ALT or DSC, for example when reaching my cruise altitude of say 15000 ft dialed in after leveling off the AP stays in ALT SEL mode, if i select AL(T to hold at FL 150 it dive bombs (and for some reason the FD will disappear for the remainder of the flight) If I dial in a lower altitude it does what you say, it starts descending at 1500ft, what I understood from the manual is you select your new altitude and press DSC and its supposed to start at a rate of 500 ft, but if I even touch the DSC button it shuts off ALT SEL which always has to be on for some reason and my plane will dive bomb again.

Looking at the code, if you are in ALT mode and push CLIMB, you turn off ALT mode (only).

If you push CLIMB a second time, you activate a 1500 ft/min climb.

 

Similar for DESCEND, only there it is -500 ft/min.

 

Try pushing the button twice and see if that works better.

 

I'm still waiting for someone to guide me to a copy of the Collins APS-65 Autopilot Pilots Guide so

I can figure out if any of this is real, or just incorrect programming.

Can someone who knows please chime in...

 

When you are at cruise altitude with AP ALT hold, when you dial in a new, lower altitude the plane instantly starts a 1,500 FPM descent. Wouldn't proper behavior be - select new altitude, press DESC, then the descent begins? Also, this happens whether you are in ALT mode or ALT SEL. Surely it is incorrect if your are in ALT mode. It should just hold your current altitude without regard to the Altitude Selector, right?

 

Ok the support guy tried his best to explain it to me, after leveling off just hit ALT SEL again to shut it off, once reaching your desired Altitude there is no need for it to be in ALT or ALT SEL mode the plane will hold the altitude dialed in, so then when your ready to descend just select your desired altitude and hit the DSC and it will descend at a rate of 500ft, if you choose to leave it in ALT SEL mode when selecting a new Altitude it command the AP to start a 1500 ft descent right away.

Thank you!

 

That (kinda) makes sense. Trying it right now.

That would be OK if the airplane would hold the current pitch when ALT is turned off..

 

Unfortunately, the AP just drops you.

 

Lets try some things to make this all work better - and if you would like to try my current effort at fixing this,

send me a PM with your email address.

You are correct Bert. When I switch off the ALT modes the altitude varies, up to 500 feet.

 

PM'd

OK - here is something to try...

 

Edit the [Autopilot] section of the aircraft.cfg file (there is one in the Lite version also!)

 

Set default_vertical_speed= 0.0

 

This way, the autopilot will not automatically start a climb or descent when you adjust the Altitude Preselector.

thanks Bert, whatever you change if you do to AP etc, you know where to send.. Always liked your correction..!