When should fuel crossfeed occur?

• A. In level cruising flight
• B. During climb
• C. During descent
• D. In takeoff configuration

Answer: (A)

The concept being tested is using fuel crossfeed to balance the fuel load between the wings so the center of gravity stays within limits and both engines have a reliable fuel supply. Crossfeeding is most appropriate when the aircraft is in a stable, level flight condition, because you can safely transfer fuel without the added complexity of changing climb or descent rate, and without the high-demand, dynamic environment of takeoff or landing.

In level cruise, fuel consumption from each wing changes gradually and you can monitor the imbalance with minimal impact on performance. If one wing becomes heavier than the other, you use the crossfeed to even things out and restore balance, while keeping engine fuel supply steady. During climb or descent, the weight and balance are changing more rapidly, and crossfeed could complicate performance and fuel management. During takeoff configuration, you want to maintain maximum engine separation and avoid crossflow during high-demand, critical phases.

So, crossfeed is best used in level cruising flight.