What is the recommended procedure for defueling aircraft with sweptback wings?

Defueling aircraft with sweptback wings typically involves defueling the outboard wing tanks first. This is because in an aircraft with sweptback wings, the outboard tanks are typically situated at the end of the wings and have a higher likelihood of creating an imbalance in weight distribution if emptied last. By defueling the outboard tanks first, the aircraft's center of gravity is more effectively maintained throughout the process, which helps to prevent any potential instability or control issues while the fuel is being removed.

Additionally, starting the defueling process with the outboard tanks ensures that gravity assists in the defueling by allowing the fuel to flow toward the center of the aircraft where the pumps are located. This is particularly important for maintaining the balance and operational integrity of the aircraft during the defueling process.

Furthermore, deferred defueling of the inboard tanks until the outboard tanks are empty ensures a more even and controlled fuel removal, which is crucial for safety and efficiency during operations.