That's right -- after nine years of service, Singapore Airlines Flights 21 and 22 are scheduled for cancellation. Snyder and most other experts suspect the airline got tired of dealing with poor profit margins on the fuel-guzzling four-engine Airbus A340. "They do use a ton of fuel, and that's always painful, says Snyder. "But the schedule advantage isn't that great either when you fly so far."Also, the world's second-longest nonstop -- a Singapore Airlines 18-hour flight between Singapore and LAX -- is scheduled to be canceled this month.