Whenever my engine is doomed I try to gain as much altitude as possible. There are three reasons for this - a) trading a few kph now means that I get extra glide range later on, b) the air is thinner the higher up you go, giving you better true airspeed and thus range and best of all c) it is a lot cooler higher up. PS - great airframe save !
that's not how you engage an spaa... also you wep and gain altitude when engine is broken, so worst case scenario you can glide to the airfield if engine dies too early. you must be one of those guys getting a kill in a tank, then die and spawn in a plane just to do some stupid stuff like that and leave the game.