UK carriers have delivered a standout performance in global airline efficiency rankings, with TUI Airways (BY/TOM) and Virgin Atlantic (VS/VIR) both featuring prominently in Cirium’s 2025 EmeraldSky Annual Review.
The report, published by aviation analytics firm Cirium, ranks the world’s 100 largest airlines based on CO₂ emissions per available seat kilometre (ASK), highlighting how operational decisions such as fleet modernisation and seat density are driving improved environmental performance across the industry.
Singapore-based Scoot took the top global position, but it was the strong UK presence within the rankings that drew particular attention. TUI Airways secured an impressive third place globally, earning Gold status and reinforcing the UK’s growing role in sustainable aviation performance.
UK carriers among global leaders
TUI Airways’ third-place ranking places it ahead of many larger international competitors, underlining the effectiveness of its relatively young fleet and high-capacity aircraft configuration. The airline recorded CO₂ emissions of just 53.6g per ASK, positioning it firmly among the world’s most efficient operators.
Meanwhile, Virgin Atlantic also delivered a notable performance, ranking seventh globally and achieving Silver status. The airline’s long-haul focus makes its efficiency particularly significant, demonstrating how modern widebody aircraft and higher-density cabins can deliver competitive emissions performance even on transatlantic routes.
Virgin Atlantic also topped the Transatlantic category, outperforming rivals on one of the world’s most competitive long-haul markets.
Jet2 and Ryanair add to UK and European strength
The UK’s presence was further reinforced by Jet2 (LS/EXS), which ranked second in the European category, highlighting its strong operational efficiency despite operating an older fleet than some low-cost rivals.
Ireland-based Ryanair (FR/RYR)—a major player in the UK market—was also recognised globally, ranking second among the world’s largest airlines by ASK. Its high-density, short-haul model continues to deliver strong emissions performance.
Across Europe, Wizz Air retained its position as one of the most efficient carriers, finishing second globally and topping the European category.
Fleet modernisation driving gains
According to Cirium, the results highlight a clear trend: airlines operating newer aircraft with higher seating density consistently outperform their peers on emissions efficiency.
Jeremy Bowen, CEO of Cirium, said: “Airline emissions performance comes down to decisions airlines can control – fleet choices, seat configuration and how aircraft are deployed on routes. The airlines at the top of these rankings have got those fundamentals right, and it shows.”
This trend is evident among UK operators, with both TUI Airways and Virgin Atlantic investing heavily in newer, more fuel-efficient aircraft in recent years.
Heathrow routes show measurable progress
The report also highlights significant improvements on specific routes, including those serving the UK. Notably, services between London Heathrow and Hong Kong operated by British Airways (BA/BAW) recorded an 18.1% reduction in CO₂ per ASK, driven by the introduction of Airbus A350-1000 aircraft.
Similarly, transatlantic routes to Heathrow from the United States have seen notable efficiency gains as airlines replace older aircraft with next-generation models such as the Airbus A330neo.
A growing role for the UK in sustainable aviation
The strong showing from UK-based airlines reflects the wider industry shift towards sustainability, with carriers increasingly balancing capacity growth against emissions reduction.
While low-cost carriers continue to dominate the top of the rankings, the performance of UK long-haul operators demonstrates that efficiency gains are achievable across all business models.
With continued investment in modern fleets and operational efficiency, UK airlines appear well positioned to remain at the forefront of global efforts to reduce aviation emissions.