There's absolutely no auto pilot, except for auto-hover, when piloting.
Auto pilot, or auto maintain altitude and speed, is a feature of many aircraft.
Within ARMA 3, having to toggle to a map view (whether for viewing or editing waypoints) can be a very risky task including the aircraft randomly loosing power due to pressing ESC or other random keys.
To suffice having no auto pilot functions, I usually ascend to an extremely high altitude to perform any of the previously mentioned simple tasks in order to recover from any anomalies. This tends to display a significant loss of forward momentum and looks very awkward for a helicopter's flight characteristics.
Granted, map viewing should be the copilot's job, but most players do not want to perform the low-level job of a copilot, or cannot simply perform this task as they're simply oblivious of the required task! (There's also a current bug of copilots causing rotor damage.)
Also, Altis inhibits some lengthy flight time to get from one point to another, and being able to quickly study a map's landing way point for safety is desirable, as the way point is usually placed by a player without any concern of surface to air missiles, etc. (ie. Landing way points are usually placed within active area of operations, versus outside.)
I should also add, thanks to some apparent inside information, the 'q' key can be utilized while in auto hover mode to stabilize the altitude of the helicopter.
Most throttles cannot set a dead zone, and the 'q' after auto-hover is set performs this task until the control device is nudged again. Also note, the 'q' key is already mapped to the raise/lower functions of a helicopter and this additional information can be easily confused for newcomers reading this bug.
I'd suggest using the forward movement key (ie. 'w'?) for activating auto maintain speed and auto maintain altitude. Matter of fact, I believe these are two separate functions within the real world aircraft instead of one auto pilot key. So maybe requiring a quick tap on 'q' and 'w', while flying might suffice?
From the sounds of it though, this is something that might be quickly fixed or implemented within a short time, or is already quietly implemented as the 'q' key already is.
Lunatico9, might be correct about this being a feature request, but it does relate to controls in a sense that this automates controls and reduces the load on the controls or game devices. Maybe even closing some other Control related bugs.
So I'll let the guys within the controls section (AKA Experts of Controls) decide whether this should be moved to feature requests. Which it may likely will be, but I'd hate to over-look the Control guys.
For those that are monitoring this bug, I've found out how to enable autopilot for the Mohawk (and maybe Ghosthawk) as well as the speed boats. This doesn't appear to work for the WY-55 Hellcat for some reason.
I figured-out the above after realizing autopilot could be enabled on the speed boats. To enable speed boat autopilot, do the following:
These are rather hack-ish type autopilot functions, but they work saving the player from straining to always maneuver a straight and level flight path. Flying greater than 5km while trying to look at the map, determining targeting information as well as communicating (all without a co-pilot) gets quite tiring.
Too bad none of the fixed wing aircraft or other fighter aircraft have autopilot yet! Albeit, most don't last longer than a few minutes because they're just in it for a cheap thrill. ;-)
There's also an old 2012 Mod for Take on Helicopters here:
"Blake's Autopilot by blakeace"
http://www.armaholic.com/page.php?id=16912