Boeing is alerting airlines about possible engine icing problems on some of its new planes—including the troubled 787 Dreamliner and the 747-8 model. The company is recommending that planes with a specific General Electric engine avoid flying near thunderstorms that might contain ice crystals. Boeing says it issued the advisory after ice crystal formation in some instances diminished engine performance. Airlines with planes affected include United, Japan Airlines, Lufthansa, and Air India. Boeing recommended that affected planes fly at least 50 nautical miles from such thunderstorms.