Which planes have four engines?
The four-engine airliners you're most likely to see are the Boeing 747 and Airbus A380, with a shrinking number of A340s and BAe 146s. Most others are military: the C-17, C-130, C-5, A400M, An-124 and the KC-135 family. The B-52 has eight.
The airliners
- Boeing 747: four engines and a hump behind the cockpit. Few airlines still fly it for passengers, but it’s still a common freighter, so a 747 overhead is often a cargo flight.
- Airbus A380: the biggest airliner, with two full decks of windows end to end. It mostly flies between major hub airports.
- Airbus A340: long and slender, with four smaller engines. Lufthansa is the largest remaining operator, and the fleet gets smaller every year. Seeing one now is a real find.
- BAe 146 and Avro RJ: a small four-engine jet with a high wing and a T-tail. Mostly gone from airline service, but several US firefighting air tankers are converted BAe 146s.
The military transports
- C-17 Globemaster III: four jet engines, a high wing, a T-tail and a fat gray body.
- C-130 Hercules: four propellers on a high wing, flown by dozens of countries. If it has four props and looks military, start here.
- Airbus A400M: also four props on a high wing, but bigger, with curved scimitar blades. The two propellers on each wing turn in opposite directions.
- C-5 Galaxy and An-124 Ruslan: two giants with four jets on a high wing. The C-5 has a T-tail; the An-124 has a conventional tail. Civilian An-124s fly outsize charter cargo: the Antonov Airlines Ruslans.
The 707 family
A whole fleet of military jets shares the shape of the 1950s Boeing 707: a swept low wing with four engines hung on pylons. The KC-135 Stratotanker refuels other aircraft through a boom under its tail. The E-3 Sentry carries a big rotating radar disc on top. The E-6 Mercury is a Navy jet on the same airframe, and the RC-135 has a lumpy, bulging nose. If it looks like an old airliner painted gray, it’s probably one of these.
Eight: the B-52
The B-52 Stratofortress has eight engines, mounted in pairs in four pods under its long, drooping wings. It first flew in 1952 and is getting new engines to keep flying for decades more. Still eight of them.
Why airliners went twin
Four engines used to be the safe way to cross an ocean: if one failed, three were left. Modern engines are so reliable that rules called ETOPS now let twin-engine jets fly routes hours from the nearest airport. The A350 is approved for up to 370 minutes. Two big engines burn less fuel and cost less to maintain than four, so the 777, 787 and A350 replaced the four-engine jets on most long-haul routes. Production of the 747 ended in 2023, and of the A380 in 2021.
How to count them from the ground
High up, count the contrails: each engine usually leaves its own, so four trails means four engines. Lower down, check where the wing sits. Four engines on a low wing is a 747, A380, A340 or the 707 family. Four on a high wing is military, or a BAe 146. Our spotter’s guide covers the other clues, and how to identify military aircraft helps with the gray ones. A 747 with a second bump on top of its hump is something else again: see the hump guide.
