It's not a bug.
AH does not have an "auto-
climb" command. Instead, it has an "auto-
speed" command, which is often used as an auto-climb..
When you activate it, the plane does whatever it needs to do in order to achieve that speed. In most planes, the default auto-speed is fairly slow, so engaging it right after take-off causes the nose to come up. In other planes though, the default auto-speed is fairly high, which will cause the plane to drop its nose if it's activated too soon after take-off.
It's often adjusted to a higher or lower speed manually, and in bombers (for example) setting it slightly above your level speed will result in a slightly increased, maintained, dive speed. This is useful for long descents, or for defending against fighters because your increased speed will make it more difficult for them to make sustained attacks without falling behind. Set it for 290-300 mph in a B17, for example, and then get into the tail gun.
Here's a link to the trainers site, which has a one page quick reference of key strokes.
http://trainers.hitechcreations.com/
