Mandatory might be a bit exagerated. Basically, if you don't like the following stuff: - military jets - landing/takeoff from moving aircraft carriers - sling operations with helicopters - piston engines that can be damaged - Reno-style aircraft racing ... then you probably don't need Acceleration and SP2 will be enough.
Thanks for the feedback. Just wodered if it improved performance, graphics, realism, etc. Not intersted in military, mostly civil, private aircraft, missions, challenges.