Scoot, Qatar, And Ryanair Top Cirium Global Airline Emissions Rankings In 2025
| Rank | Airline | Base Country | PAX CO2/ASK (g) | CO2 emissions (mt) | Flights per Year (thousands) | Fleet Age (years) | Avg. distance (km) |
| 1 | Scoot | Singapore | 51 | 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 | 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 | 4,177 |
| 9 | Pegasus | Turkey | 55.9 | 3.8 | 233 | 5 | 1,372 |
| 10 | Jetstar | Australia | 56 | 3.7 | 183 | 11.1 | 1,623 |
| 11 | Condor | Germany | 56.15 | 2.29 | 55 | 11.2 | 2,883 |
| 12 | Spirit Airlines | USA | 56.77 | 3.78 | 217 | 6.4 | 1,535 |
| 13 | Iberia | Spain | 57.03 | 4.47 | 100 | 11.5 | 2,831 |
| 14 | Volaris | Mexico | 57.33 | 3.10 | 180 | 7.5 | 1,532 |
| 15 | IndiGo | India | 57.36 | 9.84 | 796 | 4.2 | 1,082 |
| *Gold: Ranks 1-5 | Silver: Ranks 6-10 | Bronze: Ranks 11-15. For the full list of 20 airlines, please reference the report. |
Wizz Air remains among the strongest performers with a fleet averaging under five years, similar to other performers such as Frontier Airlines and IndiGo.
Long-haul operators, in contrast, are closing the gap primarily through fleet renewal, by removing from service older, less-fuel-efficient aircraft. Airlines such as Virgin Atlantic demonstrate that newer widebody aircraft and higher-capacity configurations can deliver competitive emissions performance even on long-distance routes.
Top Airlines by ASK
The table below reflects the top three most efficient global airlines, ranked by available seat kilometres (ASK). The top 10 global airlines as ranked by ASK, are listed in the full report.
| Rank | Airline | Base Country | PAX CO2/ASK (g) | CO2 emissions (mt) | Flights per Year (thousands) | Fleet Age (years) | Avg. distance (km) |
| 1 | Qatar Airways | Qatar | 60.0 | 15.4 | 198 | 10.2 | 4,221 |
| 2 | Ryanair | Ireland | 62.7 | 17.4 | 1148 | 10.1 | 1,264 |
| 3 | Turkish Airlines | Türkiye | 64.2 | 15.8 | 428 | 9.7 | 2,332 |
Regional and Key Intra Regional Rankings
The table below reflects regional rankings, as well as for well-trafficked corridors, the Transatlantic and Transpacific. Across every region, airlines with younger fleets and higher seat density continue to lead within their markets. Results in each region carry their own story as metrics of comparison change.
| Rank | Airline | Base Country | PAX CO2/ASK (g) | CO2 Emissions (mt) | Flights (000s) | Fleet Age (yrs) | Avg. Dist. (km) |
| Intra-North America | |||||||
| 1 | Frontier Airlines | USA | 54.5 | 3.0 | 185 | 4.8 | 1,402 |
| 2 | Spirit Airlines | USA | 57.4 | 3.1 | 185 | 6.5 | 1,463 |
| 3 | WestJet | Canada | 67.0 | 2.4 | 175 | 11.5 | 1,348 |
| Europe | |||||||
| 1 | Wizz Air | Hungary | 53.1 | 3.9 | 222 | 4.6 | 1,462 |
| 2 | Jet2 | UK | 57.9 | 2.8 | 110 | 13.6 | 2,206 |
| 3 | Transavia | Netherlands | 59.9 | 2.0 | 116 | 10.5 | 1,491 |
| Southeast Asia | |||||||
| 1 | VietJet Air | Vietnam | 64.5 | 1.4 | 107 | 8.2 | 941 |
| 2 | Singapore Airlines | Singapore | 66.7 | 0.90 | 45 | 5.9 | 1,181 |
| 3 | Lion Air | Indonesia | 67.1 | 1.1 | 90.0 | 13.3 | 828 |
| Latin America | |||||||
| 1 | JetSmart | Chile | 57.9 | 1.1 | 92.0 | 3.1 | 1,033 |
| 2 | Volaris | Mexico | 58.8 | 2.0 | 137 | 7.6 | 1,297 |
| 3 | VivaAerobus | Mexico | 61.4 | 2.1 | 157 | 9.1 | 1,069 |
| Transatlantic | |||||||
| 1 | Virgin Atlantic | UK | 53.7 | 1.8 | 16.9 | 6.5 | 6,759 |
| 2 | Air Canada | Canada | 54.9 | 2.7 | 24.4 | 14.4 | 6,108 |
| 3 | Aer Lingus | Ireland | 56.2 | 1.2 | 15.1 | 9.0 | 5,793 |
| Transpacific | |||||||
| 1 | Air Canada | Canada | 56.2 | 1.6 | 8.9 | 10.2 | 10,178 |
| 2 | Delta Air Lines | USA | 57.5 | 1.9 | 11.3 | 6.1 | 9,945 |
| 3 | Cathay Pacific | China | 59.8 | 2.5 | 10.8 | 9.0 | 11,933 |
Airlines Closing the Gap: Capacity Growth Without Emissions Growth
Cirium's 2025 review shows whether airlines are growing capacity faster than emissions. The table below ranks individual routes by the largest year-on-year reductions in CO2 per ASK and identifies the specific aircraft transition that drove each result. To qualify, a route must have operated at least 300 round trips in the year.
The metric highlights carriers making measurable progress, not just those already operating efficient fleets. Korean Air recorded the largest long-haul route improvements globally, driven by the transition to next-generation aircraft on key transpacific routes.
| Rank | Route | Carrier | YoY CO2/ASK Improvement | CO2/ASK 2025 (g) | Fleet Transition | Avg. Seats | Route Dist. (km) |
| 1 | ICN – SEA | Korean Air | -27.4% | 53.6 | 777-300ERs → 787-9/10s | 308 | 8,376 |
| 2 | ICN – HNL | Korean Air | -22.4% | 52.3 | 747-8s & 777-300ERs → 787-10s | 327 | 7,354 |
| 3 | JFK – DEL | American Airlines | -20.4% | 59.8 | 777-300ERs → 787-9s | 285 | 11,756 |
| 4 | KEF – SEA | Icelandair | -20.3% | 57.9 | 757-200s → A321neos | 186 | 5,810 |
| 5 | JFK – GRU | American Airlines | -19.3% | 51.5 | 777-200ERs → 787-9s | 284 | 7,663 |
| 6 | LHR – HKG | British Airways | -18.1% | 64.3 | 777/787 family → A350-1000s | 303 | 9,631 |
| 7 | BOS – LHR | Delta Air Lines | -17.0% | 60.0 | A330-200s → A330-900neos | 268 | 5,241 |
| 8 | MSP – LHR | Delta Air Lines | -16.9% | 57.2 | A330-200s → A330-900neos | 281 | 6,443 |
| 9 | MUC – BOM | Lufthansa | -16.4% | 55.5 | A340-600s → A350-900neos | 293 | 6,312 |
| 10 | HKG – CDG | Cathay Pacific | -16.4% | 62.8 | 777-300ERs → A350-900neos | 287 | 9,590 |
"The route-level data tells a clear story," said Bowen. "When airlines swap older widebodies for next-generation aircraft, emissions per seat kilometre can fall by as much as 27 percent on that route within a year. This isn't theoretical - we're measuring it on real routes with real operational data."
About the EmeraldSky emissions report
Now in its second year, Cirium's EmeraldSky Annual Review evaluates airline emissions intensity using CO2 per available seat kilometre (ASK), based on analysis of the world's 100 largest scheduled passenger airlines.
The 2025 edition also tracks year-on-year progress, measuring whether airlines are increasing capacity faster than emissions. The methodology uses flight-level operational data and is independently assured under ISAE 3000 by PwC. EmeraldSky is also accredited by the Rocky Mountain Institute as a qualified flight emissions data provider under the Pegasus Guidelines, the first climate-aligned finance framework for aviation.
About Cirium
Cirium is the world's leading aviation analytics company. It delivers aviation analytics that power decision-making for airlines, airports, travel companies, aircraft manufacturers, and financial institutions. The company provides critical and timely information, analysis, and data including airline schedules, global aircraft and fleet developments, and operational, environmental, and financial performance for companies in the sector. Cirium is part of LexisNexis Risk Solutions, a RELX business that provides information-based analytics and decision tools for professional and business customers. RELX PLC shares trade on the London, Amsterdam, and New York Stock Exchanges (ticker symbols: London: REL; Amsterdam: REN; New York: RELX).
For more information, visit cirium or follow Cirium on LinkedIn.
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