LONDON - Wednesday, 15. April 2026 AETOSWire
Scoot, the Singapore-based low-cost carrier, claimed the top spot in Cirium’s 2025 EmeraldSky Annual Review.
Qatar Airways, Ryanair, and Turkish Airlines recognized as most efficient global airlines when ranked by seat capacity.
Regional leaders include Frontier (Intra-North America), Wizz Air (Europe), Virgin Atlantic (Transatlantic), Air Canada (Transpacific), JetSmart (Latin America), and Vietjet (Asia).
(BUSINESS WIRE) -- Singapore-based Scoot has been named the world’s most emissions-efficient airline in Cirium’s 2025 EmeraldSky Annual Review, taking the top position from last year’s leader, Wizz Air. Qatar Airways, Ryanair, and Turkish Airlines were each recognized as the top three most efficient global airlines, ranked by available seat kilometres (ASK).
Cirium’s industry leading ranking is based on CO₂ per available ASK across the world’s 100 largest airlines. The methodology is independently assured by PwC to ISAE 3000. It groups airlines into Gold, Silver and Bronze tiers based on global performance, which covers the top 15 airlines as well as key regional and route performers.
“Airline emissions performance comes down to decisions airlines can control — fleet choices, seat configuration and how aircraft are deployed on routes,” said Jeremy Bowen, CEO of Cirium. “The airlines at the top of these rankings have got those fundamentals right, and it shows. Better emissions efficiency and lower fuel bills go hand in hand.”
Scoot is the first Southeast Asian carrier to lead in global airline emissions efficiency rankings. Its average seat density of 242 seats per aircraft, operating on longer average sectors, placed it in the lead position this year. The results reinforce a consistent pattern across the industry. Airlines operating younger fleets with higher seat density continue to outperform their peers on emissions efficiency, with low-cost carriers dominating the top of the rankings. Wizz Air placed second (after placing first in 2024), followed by TUI Airways, Air Europa and Frontier Airlines, with all five carriers ranking in the top five globally and earning Gold status. Each has young fleets of aircraft compared to their peers.
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.com or follow Cirium on LinkedIn.
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