What is the purpose of fuel jettison systems in aircraft?

The purpose of fuel jettison systems in aircraft is primarily to allow the crew to reduce aircraft weight for landing. In certain situations, especially when aircraft may need to return to the airport shortly after takeoff or experience an emergency, they may not be able to safely land at their current weight due to maximum landing weight restrictions. By jettisoning fuel, the aircraft can safely reduce its weight to fall within landing limits, ensuring a safer landing situation.

The other options do not accurately reflect the main function of fuel jettison systems. While fuel efficiency, engine performance, and payload capacity may be considered in the overall design and operation of an aircraft, they do not pertain to the specific functionality of fuel jettison systems. These systems are designed specifically for scenarios where the weight of the aircraft must be decreased quickly, thus emphasizing the correct choice.