Singapore Airlines (SIA) has again taken top spot in return-on-investment rankings compiled by Aviation Week & Space Technology magazine.

Return on investment (ROI) for top ranked SIA was 8.4 per cent while the number 2 carrier, Southwest Airline, stood at 8.5 per cent. Southwest's market capitalization was US$12 billion or 132 per cent of its revenues while SIA's was $14 billion or 176 per cent of its revenues.

Cathay Pacific ranked seventh, a comparatively poor performance, said the magazine, but ascribed the poorer showing to the resources the Hong Kong carrier needed to acquire Dragonair.

Rankings for airlines with revenues greater than $4 billion are SIA in first place, Southwest Airlines in second place, Iberia Lineas Aereas in third place, US Airways in fourth, British Airways in fifth, Air France-KLM in sixth, Cathay Pacific in seventh, Lufthansa in eighth, Ace Aviation Holdings in ninth, Qantas in 10th, AMR Corp in 11th, SAS in 12th, Korean Airlines in 13th, Air China in 14th, Continental in 15th, China Airlines in 16th, All Nippon Airways in 17th, Thai Airways in 18th, China Southern in 19th, Japan Airlines in 20th, Alitalia in 21st and China Eastern in 22nd.