Final answer:
While the question on the automatic performance reserve (APR) system lacks details to provide a specific percentage, APR generally commands a significant power increase to the operating engine, often ranging from 10% to 20%. Without specifics regarding aircraft and engine models, an exact figure cannot be given.
Step-by-step explanation:
The automatic performance reserve (APR) system in aircraft engines is designed to automatically command an increase in power to the operating engine in the event of the other engine failing. This system is crucial during critical phases of flight such as takeoff. However, the question appears to be incomplete or lacks sufficient detail to provide the specific percentage increase commanded by the APR system, which can vary depending on the aircraft model, engine type, and the specific APR system in question.
In general, the APR can command a significant increase in engine power, which could be in the range of 10% to 20%, but without the specific details pertaining to the aircraft or engine model, providing an exact figure isn't feasible. Typically, this system ensures that there is enough power available to maintain safe flight, especially during a one-engine inoperative scenario.
Modern aircraft are equipped with computerized engine controls that contribute to fuel efficiency and performance management. Such technology advancements have significantly improved since the era of 1970s vehicles. While the APR system's specific function is not directly related to fuel efficiency, it does underscore the technological complexity and safety features that are now standard in modern aviation.