Flight Unlimited is the first of the Flight Unlimited series of General aviation Flight Simulator games created by Looking Glass Studios. It focuses mainly on Aerobatics."
"Notable features are the pioneering physics system, landscapes and FBO interface. It was one of the first games to use 3D elevation mesh and photo-realistic images to create realistic terrain representing small areas of country in the USA and France. It supplies challenges in the form of aerobatic lessons and hoops courses, where it is required to fly through virtual 'hoops' in the sky against the clock."
Source: Wikipedia, "Flight Unlimited", available under the CC-BY-SA License.