United Airlines has retrofitted its first Boeing 737-800 with a scimitar winglet and begun flight testing.
The aircraft, registration N37277, undertook its first flight from Paine Field in Everett, Washington, on 17 July, according to the Chicago-based carrier.
"We are always looking for opportunities to reduce fuel expense by improving the efficiency of our fleet," says Ron Baur, vice-president of fleet at United, in a statement. "The next generation 737 split scimitar winglet will provide a natural hedge against rising fuel prices while simultaneously reducing carbon emissions."
The airline ordered 135 scimitar winglet pairs for its Boeing 737-900ER fleet in June and placed a separate order for its 737-800 fleet in January.
Aviation Partners Boeing, which manufactures the winglets, is targeting US Federal Aviation Administration (FAA) certification for the 737-800 in October followed by similar European approval within two months. Certification for the -900ER is expected by late February 2014.
United says that it anticipates beginning retrofits of 737-800s and -900ERs in early 2014 with revenue service following shortly after.
The airline expects scimitar winglets to generate an about 2% more fuel savings on the 737 compared to blended winglets, or a more than $200 million annual reduction in fuel costs.