The airline's non-stop service between Singapore and Los Angeles -- 18 hours -- also will be canceled this month, leaving Delta's twin-jet Boeing 777 flights from Atlanta to Johannesburg, South Africa, as the longest by time at 17 hours, CNN reported.
Both Singapore Airlines flights, which covered about 9,500 miles, are operated on Airbus A340s, four-engine jets that are less fuel efficient than twin-engines.
With their demise, the world's longest commercial flight by distance will be Qantas' four-engine Boeing 747 from Sydney to Dallas at 8,600 miles.
The longest commercial flight in history was a 2005 Boeing 777 flight from Hong Kong to London, covering 13,423 miles in 22 hours and 22 minutes.
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