This was the third Boeing 747SP to fly and join the flight test program. It was rolled out at Everett in Boeing's red-white-blue livery with Pratt & Whitney JT9D-7A engines in September 1975. Entered onto the United States Aircraft Register as N347SP she flew for the first time on September 10, 1975.

Having completed the test and certification flying required for the granting of the 747SP Type Certificate, it was returned to the hangar for refurbished in preparation for handing over to Pan Am. Reregistered as N532PA it was the second 747SP to be delivered to Pan Am. Accepted on March 29, 1976 it was configured to seat 18 First Class, 62 Business Class and 164 Economy Class passengers. Named 'Clipper Constitution' this was one of the five names that had been chosen to reflect the spirit of the upcoming bicentennial celebrations.

It operated its first revenue service when it operated a San Francisco - Honolulu flight on April 06, 1976 when the 747 scheduled to operate this service developed a technical problem. It flew the first non-stop passenger flight from Los Angeles to Tokyo on April 25, 1976 a distance of 5,478 miles. This aircraft was later chartered by the rock band 'Kiss' during its Japan tour and was suitably renamed 'Clipper Kiss'.

In April 1985 Pan Am sold its entire Pacific Division (routes and aircraft) to United Airlines for $US 750,000,000 in an attempt to overcome its dire financial problems. Ownership of N532PA was transferred to United on February 11, 1986. Retaining its current registration it entered United service with the existing Pan Am cheat line and an all-white tail. The aircraft soon acquired the airline's standard tail logo. It was reregistered as N142UA on August 01, 1986. By January 1988 it had been repainted in the United 'rainbow' livery with small company titles on the forward fuselage.

It was sold to American Finance Group on July 25, 1989 and leased back to United. By June 1991 the aircraft had acquired the larger 'United' titles but retained the existing 'rainbow' livery. An indication that its flying days were coming to an end occurred when it was observed stored at Las Vegas on August 01, 1994 without titles. Repurchased by United Airlines on September 29, 1995 and registered to United Air Lines Inc. it was ferried Las Vegas - Ardmore, Oklahoma on November 15, 1995.

N142UA was sold to Aviation Sales, Ardmore, OK in November, 1995 and cancelled from the United States Aircraft Register on December 01, 1995. Stored in the basic United livery she remained intact for some time. By December 1997 it was noted that the engines had been removed along with a number of smaller parts before being moved to the centre of the airfield. N142UA was finally scrapped by February 01, 1998 having flown 79,412 hours with 10,590 cycles.