While Airbus is looking to offer its A320 sharklet wing-tip as a retrofit, Boeing does not intend to do the same with the "dual feather" tip for the 737 Max.

Boeing Commercial Airplanes vice-president of marketing Randy Tinseth says the case is less clear, given that it already provides a blended winglet on current 737s.

"There's not much of a market to [justify] the investment," he says. The split tip, which is designed to take advantage of wing flexing, will contribute up to 1.5% additional fuel-burn reduction on top of the 4% offered by the regular blended winglet.

Tinseth says this 1.5% saving will be achieved "at long missions", those about 3,000nm (5,550km), while the figure falls to 1% for shorter sectors of 500-750nm.

Source: Air Transport Intelligence news