Singapore Airlines (SIA) has announced its 2Q net profit rose by 77.8 per cent to S$160m, compared to the same period in 2012. Asia's second biggest carrier says the improvement was down to the sale of aircraft and a higher share of profits from associated and joint venture companies. Operating profit improved to $87m, up 24.3 per cent or $17m on the same quarter in 2012. Revenue grew $107m or 2.8 per cent to $3.9bn, on the back of a five per cent growth in passenger carriage. Expenditure rose $90m or 2.4 per cent to $3.8bn, due to higher staff and non-fuel variable costs, which rose in line with an increase in capacity. Including tax write-backs, non-operating and exceptional items, net profit in the 1H of 2013-14 improved $114m to $282m, a rise of 67.9 per cent compared to the same period in 2012. Despite the profit rise, SIA warned the operating landscape for the airline industry remains challenging amid continued global economic uncertainty.