Before entering or exiting the airplane, what safety measure must be taken regarding the ejection seat?

Installing the safety pin in the ejection seat is an essential safety measure that must be taken before entering or exiting the airplane. The safety pin acts as a physical lock that prevents the inadvertent activation of the ejection seat mechanism. This is crucial because if the ejection seat were to activate unexpectedly, it could result in severe injury or even death to the pilot. By ensuring the safety pin is installed, the pilot can safely enter and exit the aircraft without the risk of an accidental ejection.

In contrast, activating the ejection seat is a procedure that should never be done unless there is an emergency situation requiring immediate egress from the aircraft. Removing the seatbelt is not a precaution taken for safety when entering or exiting the airplane, as it should remain fastened until the pilot is ready to exit safely. Checking the fuel level, while important for flight preparation, does not directly relate to the immediate safety measures concerning the ejection seat.