As global pressure to decarbonize intensifies, fleet efficiency has become one of the most powerful levers airlines can pull to reduce emissions and contain operating costs. The Aviation Sustainability Index, developed by Roland Berger in partnership with OpenAirlines, highlights striking differences in maturity across airline types and regions. Low-cost carriers emerge as clear leaders, while Asia stands out as the most advanced region in terms of fleet efficiency.
With the objective of minimizing fuel consumption and emissions per seat-kilometer, fleet efficiency strategies draw on several levers, including fleet age and aircraft technology, to maintenance standards. For airlines, this is not only a compliance requirement but a strategic avenue to reduce operating costs and strengthen competitiveness.
The Index reveals substantial variation in fleet performance, with low-cost carriers outperforming other airline types.
Low-cost carriers have widely adopted next-generation narrowbodies such as the Airbus A320neo, A321neo, and Boeing 737 MAX-8, which can burn up to 50% less fuel per seat than aircraft introduced in the 1980s. These new-technology aircraft make up 36% of low-cost fleets, nearly three times the share in mainline carriers’ fleets (13%).
In comparison, Cargo Airlines' fleets largely consist of older, medium-sized airliners. In particular, they include the Boeing 767-300, 757-200, and A300-600, which were introduced in the 1980s and 1990s.
Low-cost airlines adopt aggressive renewal strategies, keeping their fleets young (around 10 years on average). Many aircraft are sold or returned to lessors after only a few years in service, enabling rapid adoption of new models. Legacy carriers follow similar patterns, though with slightly older fleets (about 12 years on average).
Younger, more efficient aircraft bring multiple advantages:
Beyond airline type, regional dynamics tell another compelling story. Asia is the most advanced region for fleet efficiency, driven by rapid market growth and strong access to new aircraft.
Asian airlines often rely on sale-and-leaseback financing, which enables them to modernize their fleets quickly and maintain an average fleet age of about 10 years.
Europe and the Middle East follow in maturity, while North America and Africa lag behind, as shown in the figure.
Another key factor is aircraft mix. Regional jets, which have higher fuel burn per seat due to smaller capacity and older designs, account for 20% of North American fleets and 25% of African fleets, compared to a global average of 10%. By contrast, low-cost, narrow-body aircraft dominate Asian fleets.
Source: Aviation Sustainability Index, Roland Berger & OpenAirlines, 2025
The Aviation Sustainability Index offers a comprehensive assessment of more than 150 airlines worldwide across four levers of decarbonization: fleet efficiency, operational practices, Sustainable Aviation Fuels (SAF), and innovation. By comparing maturity across airline types and regions, the Index provides airlines, regulators, and financiers with actionable insights to accelerate aviation’s transition.