Final answer:
The minimum safe distance behind an aircraft's operating jet engine is about 200 feet.
Step-by-step explanation:
In aviation, the minimum safe distance behind an aircraft's operating jet engine is determined by the International Civil Aviation Organization (ICAO) and varies depending on the size of the aircraft and the power of the engine. Generally, there should be a minimum of 200 feet behind the aircraft's engines when they are running. This distance is necessary to prevent damage to structures or people due to the high temperatures, noise, and jet blast produced by the engines.