By the early 2000s , the only remaining advantage of the largest types was their ability to carry more passengers than the largest twinjets . In the years following the September 11 attacks , the increase in fuel prices and decline in the aviation industry heightened the need to minimise operating costs and expenditures . Production of the 747-400 passenger variant ceased by 2005 and deliveries of the A340 dropped to 11 per year , as they faced competition from more efficient and comparably capable twinjets
September 11 attacks
September 11 attacks
Four-engined jet aircraft