How Flying Works
Who Actually Makes Jet Engines, and Which Aircraft Use Them?
Almost every airliner in the sky is powered by an engine from one of four organizations. Which one depends on the airframe — and on some aircraft, on which engine the airline itself chose, since a handful of programs were deliberately certified with more than one supplier competing for the same airframe.
The four names behind almost every engine
CFM International dominates the narrowbody market by volume — it’s a genuine 50/50 joint venture between GE Aerospace (United States) and Safran (France), built specifically to produce the CFM56 and, more recently, the LEAP, which powers the Boeing 737 family and one option on the Airbus A320neo family. GE Aerospace separately builds its own widebody engines — the GE90 and GEnx among them — distinct from its CFM joint venture. Rolls-Royce holds a strong widebody position through its Trent engine family, and Pratt & Whitney supplies both narrowbody engines (the PW1000G geared-turbofan family) and a widebody line, competing directly with GE and Rolls-Royce on aircraft that offer an engine choice.
Which engine goes on which aircraft
Some pairings are exclusive. The Airbus A350 uses only the Rolls-Royce Trent XWB — the Trent XWB-84 on the A350-900, the larger Trent XWB-97 on the A350-1000 — an engine built specifically for that airframe with no competing option. The Airbus A220 uses only the Pratt & Whitney PW1500G. Other programs are genuinely multi-supplier: the Boeing 787 Dreamliner can be ordered with either the GE GEnx-1B or the Rolls-Royce Trent 1000, and the Airbus A320neo family can be ordered with either the CFM LEAP-1A or the Pratt & Whitney PW1100G — a real, deliberate choice airlines make based on existing fleet commonality, maintenance relationships, or negotiated pricing, not a difference customers on board would ever notice.
Why some aircraft offer a choice and others don’t
The decision comes down to how the manufacturer structured the program. Certifying an airframe with two engine options costs more up front — it means qualifying the aircraft twice, essentially — but it widens the aircraft’s appeal to airlines who already fly one supplier’s engines elsewhere in their fleet and want to keep maintenance and parts inventories consistent. A single-supplier program, by contrast, usually reflects an engine purpose-built for that one airframe from the start, where a second supplier was never realistically going to develop a competing design for it — the Trent XWB and the A350 is the clearest example, engineered together rather than adapted to fit.
The real numbers
Engine evolution, in real numbers
~5:1
Bypass ratio, CF6/CFM56 era
Earlier-generation high-bypass turbofans (1980s-90s)
9-11:1
Bypass ratio, GEnx/LEAP/Trent 1000
Current-generation engines — higher ratio, more efficiency
~15%
Fuel burn cut, LEAP vs CFM56
And a similar ~15% cut, GEnx vs the older CF6
4
Manufacturers building nearly every engine flying
GE Aerospace, Rolls-Royce, Pratt & Whitney, CFM International
What actually drove the efficiency gains
The consistent trend across every manufacturer’s newest generation is a higher bypass ratio — the proportion of air flowing around the engine’s core rather than through it. More bypass air means more of the thrust comes from that surrounding airflow instead of hot combustion exhaust, which is both quieter and meaningfully more fuel-efficient. 1980s-era engines like the CF6 and CFM56 sit around a 5:1 bypass ratio; today’s LEAP and GEnx run closer to 9:1 to 11:1. That shift, combined with higher pressure ratios, higher operating temperatures enabled by more heat-tolerant materials, and more efficient core aerodynamics, is what actually produced the real, documented roughly-15% fuel-burn improvements each new generation has delivered over the one it replaced — not any single change on its own, but the combination compounding across a full engine redesign.
Sources & Further Reading
Common Questions
Frequently Asked Questions
What actually is CFM International, and why is it separate from GE?
CFM International is a genuine 50/50 joint venture between GE Aerospace (United States) and Safran (France), formed specifically to build the CFM56 and, later, the LEAP — the engines that power most of the world's Boeing 737 and Airbus A320 family aircraft. It operates as its own entity, distinct from GE's own widebody engine line.
Why do some aircraft let an airline pick the engine, while others don't?
It comes down to how the aircraft manufacturer structured the program. Airbus and Boeing sometimes certify an airframe with more than one engine option to widen its appeal to airlines with existing supplier relationships or fleet commonality — the 787 and A320neo family both do this. Other aircraft, like the A350 and 777X, launched with a single, exclusive engine supplier, usually because that engine was purpose-built specifically for that airframe.
What does "bypass ratio" actually mean, and why does it keep going up?
It's the ratio of air that flows around the engine core versus through it. A higher bypass ratio means more of the thrust comes from that surrounding airflow rather than hot combustion exhaust, which is both quieter and significantly more fuel-efficient — which is exactly why every new engine generation has pushed the ratio higher, from around 5:1 on 1980s designs to 10:1 or higher on today's newest engines.
How much more fuel-efficient are today's engines than the previous generation?
Real, sourced figures: the LEAP burns roughly 15% less fuel than the CFM56 it replaced, and GE's GEnx burns roughly 15% less than the older CF6 it succeeds — improvements that come from a genuine combination of higher bypass ratios, more efficient core design, and more advanced heat-tolerant materials, not from any single change alone.