Plain English Meaning
Training where pilots practice recognizing and recovering from situations in which the airplane has ended up in an unintended, dangerous attitude, but done in a flight simulator on the ground instead of in a real airplane.
Full Definition
Upset Prevention and Recovery Training conducted in a qualified ground-based Flight Simulation Training Device rather than in an actual airplane. It uses the simulator to expose pilots to airplane upset scenarios — such as extreme pitch or bank attitudes, stalls, and unusual flight conditions — so they can practice recognizing and recovering from them without the risk and limitations of real-aircraft training.