What If an Engine Stops Over the Ocean?
2 min read
The short answer
If one engine stops over the ocean, the plane keeps flying safely on the other. Ocean routes are planned so an airport is always within reach on one engine. Both engines stopping is extraordinarily rare. Each engine has its own fuel supply, and the rules stop one maintenance mistake from affecting both.
One Engine: Planned For on Every Ocean Flight
Every twin-engine airliner can take off, climb, cruise and land on one engine. It has to prove this before it's allowed to carry passengers.
Over the ocean, there's an extra layer. Long ocean routes follow special rules for two-engine planes. The plane must always be able to reach a suitable airport on one engine, typically within 120 to 180 minutes.
Before take-off, the pilots are briefed on airports all along the route. The plane carries enough fuel to reach any of them on one engine, with extra to spare. Read flying over water.
What Would Actually Happen
If an engine stopped, the pilots would follow a checklist they've practised many times in the simulator. They'd come down to a lower height, where the plane flies comfortably on one engine. Then they'd fly to the nearest suitable airport and land normally.
It's a long flight on one engine — but a calm, planned one.
Why Both Engines Stopping Is So Rare
Engines on these routes are extra reliable. For the longest ocean routes, engines must stop in flight less than once in 50,000 hours. Modern engines often do far better.
Each engine is independent. Safety rules require each engine to get its fuel through its own separate system. A problem with one engine's fuel supply can't spread to the other.
They're not serviced together. On ocean routes, airlines must not do the same maintenance work on both engines during the same visit. If it can't be avoided, a different engineer must do each one, or a second engineer must check the work. So one human mistake can't affect both engines.
Even Then, the Plane Keeps Flying
This is extraordinarily unlikely. But even then, the plane wouldn't fall:
- It glides. From cruising height, an airliner can glide for many miles. Read why planes don't fall.
- Engines can be restarted in flight. Every airliner must have a way to restart its engines while flying. Pilots practise this in the simulator.
- Emergency power. Many airliners carry a small wind-driven generator that drops out of the plane's underside. It keeps the controls and key instruments working.
The Takeaway
An engine stopping over the ocean is extremely rare — and planned for on every flight. The plane flies on, safely, to an airport that was picked before you took off. Both engines stopping is so unlikely that rules, design and maintenance are all built to keep it that way.
Sources
- FAA, ETOPS and Polar Operations: https://www.faa.gov/aircraft/air_cert/design_approvals/etops
- Boeing, ETOPS: Extended Operations — engine reliability for the longest routes: https://www.boeing.com/commercial/aeromagazine/aero_22/etops_story.html
- eCFR, 14 CFR 25.953 — Fuel system independence: https://www.ecfr.gov/current/title-14/section-25.953
- eCFR, 14 CFR 121.374 — Continuous airworthiness maintenance program for two-engine ETOPS (no dual maintenance on the same visit): https://www.ecfr.gov/current/title-14/section-121.374
- eCFR, 14 CFR 25.903 — Engines (means to restart any engine in flight): https://www.ecfr.gov/current/title-14/section-25.903
- Wikipedia, Ram air turbine — emergency power for flight controls and key instruments: https://en.wikipedia.org/wiki/Ram_air_turbine
Keep reading
Flying Over Water: What You Need to Know
Why long flights over the ocean are just as safe — with an airport always within reach.
Jet Engines: How They Work and Why They're So Reliable
How jet engines work, and the testing that makes them some of the most dependable machines ever built.
Backup Systems: A Spare for Everything That Matters
How planes are designed so that no single fault can put a flight at risk — with backups for every important system.