It’s unrealistic to think every non-pilot flying companion can master the autopilot, especially under the stress of dealing with a slumped-over pilot. But it sure is worth a try. Whether your autopilot is highly integrated (Garmin’s GFC 700 comes to mind) or is a simple wing leveler with heading hold, show them how to use it and keep reviewing it on every flight. Got a model with a Level button? Stress that this might be the first button they’ll push while they sort things out. Put the airplane into a bank and demonstrate what it does to correct. Then work into basic coupling commands.
Start as every pilot new to an autopilot should and give your companion the pilot’s guide. It’s filled with jargon, but by reviewing it with them you can likely dumb it down enough where anyone can understand it. Continue to reinforce the button-pushing on every trip you fly, even if your companion is paying attention to nothing else. Simply put, show them how you’re making the airplane go to the destination. If the autopilot is interfaced to a GPS navigator as many are, that’s more to cover. Again, simplify it and start with the navigator’s Direct button and simply concentrate on teaching how to make the autopilot fly to an airport. Baby steps. As they become more comfortable, show them how to make the autopilot join an approach. The problem, of course, is that with autopilot programming comes the prerequisite of understanding navigation. Still, with good help from ATC (make sure the companion knows the model of the autopilot) they might be able to line the airplane up on a runway.
Last, show them how to disconnect the autopilot. If you had it engaged before your incapacitation, they should know how to take command of the airplane or cancel their own botched input. I would also make an abbreviated ops guide and have the companion use it to make the autopilot work while you coach. A good reference for constructing this is found in the Pilot Workshops (www.pilotsorkshops.com) Flying Companion book, which also has 50 tasks a non-pilot can take on. Some of those include commanding the autopilot.