Which area must vehicle operators avoid entering when aircraft engines are running?

When aircraft engines are running, vehicle operators must avoid entering the tail of the aircraft stand. This area is critical because the engine exhaust from an aircraft can produce a strong blast of air and debris that can be dangerous to personnel and vehicles nearby. The tail of the stand is particularly hazardous because of the risk of being struck by the thrust or being in the path of the jet blast, which can cause loss of control of vehicles or injury to personnel.

Understanding the specific zones around an aircraft is essential for ensuring safety on the airside, especially during operations when engines are running. This knowledge helps prevent accidents and ensures a safe environment for both ground personnel and aircraft.

In contrast, while the runway incursion zone, uncontrolled taxiway, and vehicle corridor are also important areas that require caution, they do not have the same direct risk associated with running aircraft engines as the tail of the stand does. The focus must be on areas that pose immediate dangers in the presence of jet engines, making the tail of the stand the correct answer.