Japan Airlines, the world’s second-largest Boeing 787 Dreamliner operator, replaced 787s on two routes to avoid cancellations after Boeing ordered Dreamliner jets with General Electric engines to keep away from certain weather.

Japan Airlines will replace 787s on flights between Tokyo and Delhi with 777s from Nov. 25, and will switch to 767s on its Tokyo-Singapore route the same day, it said in a statement today.

Boeing told customers with some GE-powered engines to avoid flying within 50 nautical miles of thunderstorms to reduce chances of ice crystals forming in the engines and reducing thrust, the planemaker said in an e-mailed statement Friday.

There have been six cases since April of planes with GEnx engines temporarily losing thrust in high-altitude icing conditions, according to an e-mailed statement from GE.

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“There may be cases where we wouldn’t be able to go all the way round the cloud formation and we’d have to turn back,” Yuichi Kitada, a general manager in JAL’s engineering department, said today in Tokyo. “We’re at the first step of discussing a solution to this problem with Boeing and GE.”

GE is working on software modifications to eliminate the problem and expects them to be available in the first quarter of next year, its statement said.

ANA, the world’s biggest operator of 787s, uses Rolls-Royce Holdings Plc engines on its Dreamliners and hasn’t received any notification to avoid certain weather conditions, Maho Ito, a spokeswoman for the carrier, said by phone.