In most fuel jettison systems, how is fuel moved overboard?

In most fuel jettison systems, fuel is moved overboard primarily by the use of boost pumps. This method is effective because boost pumps are designed to increase the pressure of the fuel, ensuring that it can be expelled from the aircraft efficiently and quickly. The operation of these pumps allows for a controlled and rapid jettisoning of fuel, which is crucial during flight operations, especially in situations where an aircraft must reach a certain landing weight after takeoff.

While other methods may seem feasible, they do not offer the same level of control and efficiency. Gravity alone would depend on the aircraft's altitude and orientation, making it unreliable for jettisoning fuel quickly and effectively in response to changing flight conditions. Engine-driven fuel pumps are primarily used for supplying fuel to the engines and may not be able to divert fuel for jettisoning purposes. Manual operation could complicate the process and introduce the potential for human error, which is less desirable in critical situations like fuel jettisoning.

Thus, boost pumps stand out as the most reliable and efficient means of moving fuel overboard in most aircraft jettison systems.