Singapore Airlines new business-class seats. Courtesy: Singapore Airlines Singapore Airlines is planning to add a four-seat first class to the Airbus aircraft it uses for its longest routes, a bet to attract high-spending travelers to flights that can top 17 hours. The carrier will add the new seats to seven Airbus A350-900 URLs, or ultra-long-range aircraft that it uses for lengthy trips, including its longest, between New York and Singapore.