autopilot armed/coupled

[jeroen79]

How would I determine wether the autopilot is still armed for nav/approach or already coupled to it?
I setup some rules myself:
To arm:

• autopilot or flight director must be on
• nav or approach mode must be active
• wingleveler or heading mode is active or cdi is deflected > 3/4

To couple:

• autopilot or flight director must be on
• nav or approach mode must be active
• wingleveler and heading mode are not active and cdi is deflected < 3/4

Is that right or are there better ways?

[n4gix]

I'm honestly not sure just what you are asking for, as the default autopilot system is fully automatic.

There are a number of token variables that will provide you with information on the current state of the autopilot system:

(A:AUTOPILOT APPROACH HOLD,bool) // will be 1 if the approach hold mode is selected

(A:AUTOPILOT BACKCOURSE HOLD,bool) // will be 1 if the backcourse approach mode is selected

(A:NAV HAS LOCALIZER:index,bool) // will be 1 is the localizer has been captured

(A:NAV HAS GLIDE SLOPE:index,bool) // will be 1 if the glideslope has been captured

[Flying Officer Jevans]

I'd imagine you want these for indicator lights, in which case I'd use the last two Bill listed.

[jeroen79]

The autopilot is indeed automatic but if you set it into nav mode and the aircraft isn't quite on the selected radial yet it will stay in the previous mode (heading hold or wingleveler) and only 'arm' the nav mode.
When it gets close enough it will cancel the previous mode and start steering based on now 'coupled' the nav mode.

Does NAV HAS LOCALIZER just tell if the selected navaid has a localizer or does it tell if the localizer signal is actually being received?

[Flying Officer Jevans]

It tells you if a signal is being received.