up/down switch on most autopilots??

[Guest]

I'm trying to recreate a typical autopilot control for my home cockpit but wonder what the up/down switch is for on a Bendix/King type. Is it to change the altitude setting or the V/S? Or is it something else entirely? Thanks!David

[Guest DNelson]

On the KAP140 that I've flown, the up/down buttons are used for both vertical speed and altitude hold. If you're currently in VS mode (the default when the autopilot is powered up), the up/down buttons change the vertical speed by +/- 100 ft/min. If you're in altitude hold mode, the up/down buttons will increase/decrease the held altitude by 20 ft per button press.Dan

[Guest]

Dan,That makes perfect sense! Not sure how I'm going to emulate it with a single switch but I'll try. Thanks for the help!David