LONDON— Global aviation analytics firm Cirium has released its 2025 EmeraldSky Annual Review, naming Scoot (TR) as the world’s most emissions-efficient airline.
The Singapore-based carrier topped the rankings based on CO₂ emissions per available seat kilometre (ASK), overtaking last year’s leader Wizz Air (W6).
The report also highlights Qatar Airways (QR), Ryanair (FR), and Turkish Airlines (TK) as the most efficient global airlines when measured by seat capacity. The rankings evaluate the world’s 100 largest airlines using detailed operational data and verified emissions metrics.
Global Efficiency Rankings
Scoot secured the top position with a CO₂ intensity of 51 grams per ASK, supported by high seat density and longer average routes.
Wizz Air followed closely, while TUI Airways, Air Europa, and Frontier Airlines completed the top five, earning EmeraldSky Gold status.
Low-cost carriers dominated the upper tier due to their dense seating configurations and relatively young fleets. These structural advantages enable them to distribute emissions across more passengers, lowering per-seat carbon output.
Airlines ranked between sixth and tenth, including TUIfly and Virgin Atlantic, earned Silver status. Meanwhile, carriers such as Condor, Iberia, and IndiGo were placed in the Bronze tier, reflecting moderate but improving efficiency levels.
| Rank | Airline | Base Country | PAX CO2/ASK (g) | CO2 Emissions (mt) | Flights per Year (000s) | Fleet Age (years) | Avg. Distance (km) |
|---|---|---|---|---|---|---|---|
| 1 | Scoot | Singapore | 51.0 | 2.0 | 65 | 6.7 | 2,157 |
| 2 | Wizz Air | Hungary | 52.9 | 6.2 | 335 | 4.7 | 1,547 |
| 3 | TUI Airways | UK | 53.6 | 2.2 | 66 | 9.7 | 2,862 |
| 4 | Air Europa | Spain | 53.9 | 2.1 | 69 | 10.0 | 2,023 |
| 5 | Frontier Airlines | USA | 54.1 | 3.5 | 208 | 4.8 | 1,470 |
| 6 | TUIfly | Germany | 54.4 | 1.6 | 58 | 10.6 | 2,475 |
| 7 | Virgin Atlantic | UK | 54.5 | 2.8 | 27 | 6.8 | 6,566 |
| 8 | AirAsia X | Malaysia | 54.8 | 1.6 | 20 | 14.0 | 4,177 |
| 9 | Pegasus | Turkey | 55.9 | 3.8 | 233 | 5.0 | 1,372 |
| 10 | Jetstar | Australia | 56.0 | 3.7 | 183 | 11.1 | 1,623 |
Top ASK Performers
When ranked by available seat kilometres, Qatar Airways led the global category despite operating long-haul routes. The airline achieved a CO₂ intensity of 60 grams per ASK, reflecting efficiency gains from fleet modernization.
Ryanair ranked second in this category, supported by its extensive short-haul network and high aircraft utilization. Turkish Airlines placed third, balancing long-haul and regional operations with a modern fleet strategy.
These rankings show that both low-cost and full-service carriers can achieve strong efficiency outcomes through different operational models. Fleet renewal and route optimization remain critical factors.
Regional Leaders 2025
The report also identified regional leaders across key aviation markets. Frontier Airlines led intra-North America, while Wizz Air topped the European category with strong short-haul efficiency.
In Southeast Asia, VietJet Air emerged as the most efficient operator, ahead of Singapore Airlines and Lion Air. JetSmart led Latin America, while Virgin Atlantic dominated transatlantic routes with efficient widebody operations.
Air Canada ranked first in the transpacific category, followed by Delta Air Lines and Cathay Pacific. These results highlight the growing role of next-generation aircraft in reducing emissions on long-haul routes.
The report also emphasized measurable progress at the route level. Airlines such as Korean Air and American Airlines recorded emissions reductions of over 20 percent on select routes by replacing older aircraft with newer, fuel-efficient models.
Cirium’s analysis confirms that airlines investing in modern fleets and higher seat density continue to outperform peers. The findings also show that emissions efficiency improvements often align with lower operating costs, reinforcing the business case for sustainability in aviation.
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