The announcement by the world’s largest airline, Delta Air Lines Inc., that it planned to upgrade the interiors of its existing planes and improve their fuel efficiency was notable in that it contained no new aircraft orders for either The Boeing Co. or its European rival, Airbus.

But the announcement wasn’t totally bereft of encouraging news for the Big B. Delta announced it will add fuel-saving winglets to 170 planes in its fleet.

Those winglets are made by a Boeing joint venture with Seattle’s Aviation Partners.

The curved winglets – appendages at the end of the wings of existing Boeing planes that are perpendicular to the wing surface – can improve fuel economy, reduce takeoff distances, cut noise and reduce maintenance.

John Gillie, staff writer