Ben Mutzabaugh

USA TODAY

Attention Boeing 747 lovers: The clock is ticking to catch a flight on one of the two U.S. airlines that fly the aircraft.

United said on Tuesday that it expects to retire all 20 of the 747s in its fleet by October 2018.

The airline has long said it plans to phase out the aircraft, but reiterated its plan Tuesday during its "Investors Day" call with shareholders.

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United is shifting its 747 flying to newer widebody jets, including the Boeing 787 Dreamliner and Boeing 777 models that the carrier has ordered.

The 747s in United's fleet – all 747-400 variants of the jet – seat 374 passengers.

United's current Boeing 777-200s seat anywhere from 266 to 364 passengers, based on the various configurations it has for the aircraft. United's 787-8 and 787-9 Dreamliner models seat 219 and 252 passengers, respectively.

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Delta Air Lines is the only other U.S. carrier that currently uses 747s for passenger service. Like United, Delta also has begun to phase out its models of the jet. The carrier is on record as saying it expects to retire its last 747 by the end of next year.

Delta spokesman Morgan Durrant tells Today in the Sky that the airline expects to have five 747-400s remaining in service by the end of 2016. Delta will use several models to replace its 747s. They include new Airbus A330s that already are being delivered to the carrier as well as new Airbus A350s that Delta expects to begin receiving next year.

Delta’s 747s accommodate 376 passengers.

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