The ON position of the fuel transfer pump switch is used:

• A. On the ground or as a back up if the automatic system fails
• B. In flight during normal operation
• C. During takeoff only
• D. In case of low fuel in center tank

Answer: (A)

The switch in the ON position provides manual control of the fuel transfer pumps. This is used when the aircraft is on the ground to prime or ensure fuel can be transferred into the center tank for engine start and for proper system balance, and it also serves as a backup if the automatic fuel transfer system fails. In normal flight you rely on the AUTO mode, which handles transfer automatically. Using the ON position during takeoff or to respond to a low center-tank condition isn’t the standard procedure; the primary reason for ON is ground priming or backup operation if the automatic system isn’t available.