What the 787 fuel cutoff switch does
The fuel cutoff switch on a Boeing 787 is a manual valve that stops fuel flow to the engines when you move it to the OFF position. It sits in the flight deck and gives the flight crew direct control over fuel delivery — independent of any automatic system. When the switch is OFF, fuel cannot reach the engines, even if the fuel pumps are running and fuel is available in the tanks.
This is a safety device, not a fuel-saving device. It exists so pilots can shut down engines in an emergency — during an engine fire, a severe malfunction, or a controlled descent where engine power is no longer needed. The switch is also used during normal ground operations to prevent fuel from flowing while the aircraft is parked or being serviced.
The 787 has two fuel cutoff switches, one for each engine. Each switch controls only its own engine, so a pilot can shut down one engine while keeping the other running if needed.
Key Takeaways
- The fuel cutoff switch is a manual valve that stops fuel flow to each engine when moved to OFF, giving pilots direct control independent of automatic systems.
- It is a safety device used during emergencies, engine shutdowns, and ground operations — not a fuel-saving feature during flight.
- The 787 has two switches, one for each engine, so pilots can shut down one engine while keeping the other running.
- Moving the switch to ON restores fuel flow; the switch does not automatically reset and must be manually moved back to restore engine operation.
Where the switch is located and how pilots use it
The fuel cutoff switches are located on the flight deck overhead panel, grouped with other engine and fuel system controls. Each switch is clearly labeled with its engine number and marked with ON and OFF positions. The switches are designed to be straightforward to reach and operate without looking away from the instruments.
During normal flight, the switches remain in the ON position. Pilots move a switch to OFF only when they intend to shut down that engine. This might happen during a controlled descent to a landing, during an engine emergency, or when an engine has failed and cannot be restarted. Once the switch is OFF, fuel stops flowing to that engine within seconds, and the engine will wind down and stop.
To restore fuel flow after shutting down an engine, the pilot moves the switch back to ON. The engine will not restart automatically — the pilot must use the engine start system to restart it. This prevents accidental fuel flow if the switch is bumped or moved unintentionally.
How the fuel cutoff switch differs from other engine controls
The fuel cutoff switch is separate from the throttle, the engine start switch, and the fuel pump switches. The throttle controls engine power but does not stop fuel flow. The engine start switch begins the ignition sequence but does not control fuel delivery. The fuel pump switches control the electric pumps that move fuel from the tanks, but fuel can still flow to the engines through gravity if the pumps are off and the cutoff switch is ON.
The cutoff switch is the only control that completely blocks fuel from reaching the engines. This is why it is the primary tool for shutting down an engine in an emergency. A pilot does not have to wait for pumps to stop or throttle to spool down — moving the cutoff switch to OFF stops fuel flow when ready.
On older aircraft, fuel cutoff was sometimes controlled by a fuel selector valve that could direct fuel to different engines or tanks. The 787 design simplifies this by using dedicated cutoff switches for each engine, with fuel automatically drawn from the correct tank by the fuel system.
Emergency scenarios where the cutoff switch is used
During an engine fire, pilots will move the fuel cutoff switch to OFF as part of the fire-suppression procedure. Cutting off fuel stops the fire from spreading and allows the fire-suppression system to extinguish the flames. The switch is moved to OFF before other actions because stopping fuel flow is the fastest way to control a fire.
If an engine suffers a severe mechanical failure — such as a compressor stall, a bearing failure, or uncontrolled vibration — pilots may shut it down using the cutoff switch to prevent further damage and to stabilize the aircraft. The 787 is designed to fly safely on one engine, so losing one engine is not an emergency by itself, but the pilots need to stop fuel flow to prevent the damaged engine from causing additional problems.
During a normal descent to landing, pilots may shut down one or both engines before touchdown to reduce fuel burn during the final approach. This is not an emergency procedure but a routine fuel-management step on some flights.
What happens when the cutoff switch is moved to OFF
When a pilot moves the fuel cutoff switch to OFF, a valve in the fuel line closes within one to two seconds. Fuel that is already in the fuel manifold and engine fuel nozzles will burn off quickly, but no new fuel enters the engine. The engine's combustion process stops, and the engine begins to wind down.
The engine does not stop when ready. Depending on the engine's speed and load at the moment the switch is moved, it may take 30 seconds to several minutes for the engine to come to a complete stop. During this time, the engine is coasting down under its own inertia, and the pilot can monitor its shutdown on the engine instruments.
Once the engine has stopped, it will not restart without pilot action. The pilot must move the fuel cutoff switch back to ON and then use the engine start system to begin the restart sequence. This design prevents an engine from restarting accidentally if vibration or a bump moves the switch.
Maintenance and testing of the fuel cutoff switch
The fuel cutoff switches are tested regularly as part of the 787's scheduled maintenance program. Maintenance technicians verify that each switch moves smoothly, that the valve closes completely when the switch is OFF, and that fuel flow resumes when the switch is returned to ON. The switches are also checked for proper labeling and for any signs of corrosion or wear.
The switches themselves are robust mechanical devices with few moving parts, so they rarely fail. However, if a switch becomes stuck, difficult to move, or fails to stop fuel flow, it must be replaced before the aircraft can return to service. A stuck switch is a serious issue because it prevents pilots from controlling fuel flow in an emergency.
Pilots also perform a functional check of the fuel cutoff switches during the preflight inspection. They move each switch through its full range of motion and verify that it moves freely and returns to the ON position when released. This check takes only a few seconds but confirms that the switches are ready for use if needed during flight.
Why the cutoff switch is not a fuel-saving feature
Some people assume that the fuel cutoff switch could be used to save fuel during cruise by shutting down one engine and coasting on the other. This does not work in practice. The 787 is designed to cruise efficiently on both engines, and the fuel burned by one engine during cruise is less than the extra fuel burned by the remaining engine if it has to work harder to maintain altitude and speed.
Additionally, shutting down an engine in cruise creates handling and stability challenges. The aircraft becomes asymmetrical, and the pilot must use more rudder input to keep the aircraft flying straight. This extra control input increases drag and fuel burn, offsetting any savings from running one engine instead of two.
The fuel cutoff switch exists for safety and emergency control, not for routine fuel management. Fuel efficiency on the 787 comes from aerodynamic design, engine efficiency, weight reduction, and flight planning — not from shutting down engines during normal operations.
Frequently Asked Questions
Can a pilot accidentally move the fuel cutoff switch during flight?
The switches are located on the overhead panel where they are not in the normal path of pilot movement, and they require deliberate action to move. However, some 787 operators have added protective covers or guards over the switches to prevent accidental movement during turbulence or during maintenance work in the flight deck.
What happens if both fuel cutoff switches are moved to OFF?
Both engines will shut down, and the aircraft will lose all engine power. The 787 can glide safely to a landing with both engines off, and pilots train for this scenario. However, this situation would only occur if both switches were moved to OFF intentionally or if a catastrophic failure affected both switches simultaneously, which is extremely unlikely.
Is the fuel cutoff switch the same on all Boeing aircraft?
The basic function is the same on all Boeing aircraft — to stop fuel flow to the engines — but the location, design, and labeling vary by aircraft type. The 787 design is newer and incorporates lessons learned from decades of operation on earlier models. Pilots transitioning between aircraft types receive training on the specific location and operation of the fuel cutoff switches for each aircraft.
Can the fuel cutoff switch be operated from the cabin or remotely?
No. The fuel cutoff switches are located in the flight deck and can only be operated by the flight crew. There is no remote operation, no cabin crew override, and no automatic system that moves the switches. This design ensures that only the pilots who are monitoring the engines and flight systems can control fuel flow.
What is the difference between the fuel cutoff switch and the engine fire switch?
The fuel cutoff switch stops fuel flow to the engine. The engine fire switch activates the fire-suppression system, which discharges fire-suppression agent into the engine nacelle to extinguish a fire. During an engine fire, pilots move both switches — the fire switch first to set up suppression, and the fuel cutoff switch to stop fuel flow and prevent the fire from spreading.