What is the maximum altitude for fuel crossfeed operation?

The maximum altitude for fuel crossfeed operation is set to ensure safe and efficient functioning of the aircraft's fuel system. At 20,000 feet, fuel crossfeed allows for balanced fuel distribution between tanks, which can be crucial for maintaining aircraft stability and performance. This altitude is chosen based on factors such as the operational capabilities of the fuel system and the physiological effects of altitude on crew and systems.

Operating above this altitude without adequate fuel balance can lead to issues with aircraft control and may increase the risk of an imbalance, which can affect performance and safety. Therefore, the limit emphasizes the importance of managing fuel at various altitudes to prevent complications that might arise during flight.