The airline says it expects to save about 940 gallons of fuel on the flights, which will carry paying passengers. The testing includes a trip from Frankfurt to Chicago on a United 777 (triple-seven), and a return trip on the same plane.
Commercial flights usually stay at a precise altitude. But this flight will drift up and down as much as 3,000 feet. That way the pilots won’t need to burn extra fuel maintaining a precise altitude.
Several airlines have been testing ways to cut their fuel bill. Last year American Airlines tested fuel-saving technology and practices on a Paris-to-Miami flight. And United used synthetic fuel on a test flight in April.