Delta Air Lines is quietly upgrading the tips of its Boeing 737 wings. Since 2015, the airline has been replacing the older blended winglets on its 737-800s and 737-900ERs with split scimitar winglets — a design with curved sections extending both above and below the wingtip, named after the curved Middle Eastern sword. The change looks small, but the numbers add up: blended winglets cut fuel burn by around 3.3%, while split scimitars push that to as much as 5.5%. For Delta, the retrofit programme is expected to save nearly 3.3 million gallons of fuel a year.
The technology comes from Aviation Partners Boeing, which made split scimitar winglets available for the 737-800 and 737-900ER in 2014. Southwest Airlines flew the first retrofitted 737-800 in April 2014, and Delta followed with its 737-900ERs a year later. In 2022, Delta placed fresh orders to extend the retrofit across more of its 737-800 fleet — over 200 737 family jets in total — with Aviation Partners executives framing the deal as part of the airline's sustainability push.
What does this mean for passengers? The winglet work has been paired with an interior refresh on select 737-800s. Delta is installing the first class seat it debuted on its A321neos in 2022, which brings more privacy, extra storage and a sturdier tray table. Delta Comfort+ and Main Cabin cabins are getting upgrades too, including better seatback screens and touchless lavatory features. So on many Delta 737 flights, a newer-feeling cabin could arrive with very little fanfare.
There's a wrinkle further down the line. Delta has 100 Boeing 737 MAX 10s on order at a list price of $135 million each, but deliveries have slipped from 2025 to 2026, and the type isn't expected to enter service until 2027. The MAX 10 doesn't use split scimitar winglets at all — it gets a new split-tip design specific to the MAX family. Boeing's ongoing scrutiny from the FAA after the Alaska Airlines door plug incident has added uncertainty, though Delta's CEO Ed Bastian has noted contract protections against further delays.
Winglets might sound like a niche engineering story, but it directly shapes the planes travellers end up on. Fuel efficiency affects fares and emissions, and the cabin retrofits mean the difference between an aging interior and a genuinely refreshed one on a workhorse aircraft that flies short and medium-haul routes across the US, Caribbean and Latin America. If you're booking Delta and can pick your aircraft, a retrofitted 737-800 is now one of the more comfortable narrow-body options in the fleet.
There's even some industry drama in the background: Aviation Partners once worked with Airbus, only for the European manufacturer to introduce its near-identical 'sharklets' in 2011 and challenge the American firm's 1994 patent. Airbus settled in 2018 with a substantial payment. Not bad for a few metres of curved metal at the end of a wing.
