The days may be numbered for the world’s largest passenger aircraft.

Airbus, the European aerospace group that makes the A380 superjumbo, said on Monday that it would have to end production of the plane if its only major customer, Emirates, did not order more.

The admission by John Leahy, the company’s chief operating officer, was the latest indication that Airbus miscalculated more than two decades ago when it bet that clogged runways would create demand for larger planes that could deliver more people with fewer landing slots. Instead, airlines bypassed the major hubs and ordered midsize planes that could fly directly between regional airports.

“The A380 was better suited to 1995, before air routes fragmented,” said Richard Aboulafia, vice president of analysis at Teal Group Corp., a consulting firm in Fairfax, Va.

Airbus said Monday that it has not given up on the plane, but acknowledged that it is endangered.

“If we can’t work out a deal with Emirates, I think there is no choice but to shut down the program,” Mr. Leahy said during a webcast with journalists.