Delta Replaces Blended Winglets With Split Scimitar Winglets on 737-800 and 737-900ER Fleet for Fuel Savings
Why It MattersWinglet swaps on in-service narrowbodies let carriers extract fuel savings from existing fleets while new-aircraft deliveries slip, tying fleet efficiency to retrofit programmes instead of delivery schedules.
What happened
Delta Air Lines decided in 2015 to replace the blended winglets on its Boeing 737-800 and 737-900ER aircraft with split scimitar winglets. Aviation Partners makes the winglets and offered them for both types from 2014. Split scimitar winglets have been found to produce up to 5.5% fuel savings per aircraft, against 3.3% for blended winglets. Delta expects the programme to save nearly 3.3 million gallons of fuel per year.
Southwest Airlines was the first to order a retrofit, and a Southwest 737-800 made its first flight with split scimitar winglets on April 14, 2014. Delta began similar retrofitting in 2015, installing the winglets on its 737-900ERs. In 2022, Aviation Partners announced that Delta had placed further orders to outfit its 737-800 fleet, and had also ordered winglets for more of its newer 737-900ERs.
Delta's fleet includes more than 200 Boeing 737 family aircraft. According to ch-aviation, 77 are 737-800s and 163 are 737-900ERs, listed as delivered, while 100 737 MAX 10s are on order. The 737 MAX 10's winglets look similar to split scimitar winglets but are slightly different split-tip winglets, with a more acute angle of the split and no gradual sweep from the wing to the winglet.
Delta announced plans in July 2022 to add 100 Boeing 737 MAX aircraft, with options for 30 more. Deliveries, initially scheduled to begin in 2025, were postponed by Boeing to 2026. The type's certification has now been completed, but it will not enter service until 2027. Bastian said there are "several issues that need to be addressed" with the aircraft, and the company remains in ongoing discussions with Boeing about the roll-out. Each 737 MAX 10 has a list price of $135 million.
Delta is also refreshing the cabins of select 737-800s and adding its newest first class seat, which debuted in 2022 on the airline's Airbus A321neo jets. Delta Comfort+ and Main Cabin have also been refreshed.
Industry impact & what to watch
Winglet retrofits are one of the cheaper ways an operator can lower fuel burn on aircraft it already owns. The gain per aircraft is incremental, a few percentage points, but it applies across every tail in the fleet and starts as soon as each aircraft is modified, without waiting for new-build deliveries. That matters most when a new type is late: the 737 MAX 10 has slid from 2025 to 2026 deliveries and now to a 2027 entry into service, so the efficiency Delta can capture in the meantime comes largely from upgrading the 737-800s and 737-900ERs it already operates.
The case also shows how the retrofit market works for the supplier. Aviation Partners first sold the split scimitar design to Southwest in 2014, then to Delta in stages, with the 2022 order widening the scope from the 737-900ER to the 737-800. A single large operator can therefore generate repeat orders over many years as it decides which sub-fleets justify the work.
The next milestone that would settle how much of Delta's narrowbody efficiency rests on retrofits is the outcome of its ongoing discussions with Boeing about the MAX 10 roll-out, which Bastian tied to several issues still to be addressed.
