Commercial jet maker Airbus is staying humble even as Boeing flounders. There's a reason for that.

Europe’s Airbus had established a clear sales lead over Boeing even before the American company encountered more fallout from manufacturing troubles and ongoing safety concerns. Airbus has outpaced Boeing for five straight years in plane orders and deliveries. And now Boeing is facing a government-mandated production cap on its best-selling plane. Yet aviation analysts say the European company is unlikely to extend its advantage much further despite having customers clamoring for more commercial aircraft. That's because Airbus already is making planes as fast as it can and is sold out for the rest of the decade. Manufacturing constraints at both companies are bad news for travelers as well as airlines.