In a filing with the Securities and Exchange Commission Wednesday, Boeing said, “It is reasonably possible that we could decide to end production of the 747.”

Demand for the four-engine jumbo jet has been falling for years, and it’s now mainly used for cargo. Airlines have taken to more fuel-efficient twin-engine jets for passengers.

The news of a possible end for the 747 comes after Boeing announced in January that it was cutting production in half, taking a $569 million charge in the fourth quarter as it faced dwindling sales. The aircraft maker has said that the costs of making the wide-body plane outweighed its sales, resulting in an imbalance of about $1 billion.

In Wednesday’s filing with the SEC, Boeing (BA) said the production rate on the 747, which was at 1.5 per month in June 2015, has gradually dropped to 1 a month in July 2016.

The “Queen of the Skies” made its first flight in 1969. The U.S. President’s Air Force One is a variant of the 747. Despite falling sales, it was reported that the plane is being used to upgrade the U.S. Air Force One presidential fleet, but that will be a small number.