Watch: How do fuel switches on an aeroplane work?

Aircraft fuel systems are intricately designed to ensure a constant and managed supply of fuel to the engines, and central to this operation are the fuel switches. These critical controls allow pilots to precisely manage the flow of fuel from an aircraft’s various tanks to its engines. Typically, these switches enable pilots to select which fuel tanks feed which engine, balance fuel load across the aircraft to maintain stability, or isolate a fuel tank in case of contamination or an emergency. They can also be used to shut off fuel flow entirely to an engine or to all engines, a function vital for safety protocols, maintenance procedures, or in specific emergency situations. The proper manipulation of these controls is essential for flight performance, ensuring optimal engine operation and overall aircraft stability. The high stakes involved in their operation were underscored by a preliminary report investigating a recent Air India incident, which indicated that both fuel switches were found in the off position. This finding highlights the profound and immediate impact these seemingly simple controls have on an aircraft’s ability to remain airborne and operate safely, emphasizing why their functionality and correct usage are paramount to aviation safety.