When utilizing gravity cross flow in flight, which maneuver can enhance the transfer?

• A. Gravity cross flow requires a sideslip
• B. A sideslip maneuver can enhance the transfer
• C. Gravity cross flow improves with altitude
• D. It stops the transfer

Answer: (B)

Gravity-driven crossflow relies on a difference in vertical height between the fuel tanks to push fuel through the crossfeed line. The bigger the head difference, the faster the transfer.

A sideslip changes the airplane’s lateral attitude in a way that can create a vertical height difference between the left and right tanks, increasing the driving head for gravity to move fuel from the higher tank to the lower one. Because of that, performing a sideslip can enhance the transfer.

It's not required to slip, and altitude alone doesn't guarantee more transfer—the head difference is what matters, and a sideslip is one practical way to increase it. The transfer isn’t stopped by flight attitude alone, so the statement that it stops the transfer isn’t correct.