DALLAS — Today in Aviation, a Boeing 747SP operating Pan Am flight 50 flew to/from San Francisco International Airport (SFO) via both poles on October 28–30, 1977. The flight took place in celebration of Pan Am's 50th anniversary.

Pan Am's Flight 50 made aviation history by setting a speed record for a polar circumnavigation. According to the Fédération Aéronautique Internationale, its average speed was 487 mph (784 km/hr). The one-off flight on the new Boeing Special Performance 747, named 'Clipper New Horizons', started in San Francisco, flew over the North Pole, and landed in London, its next destination.

The aircraft flew to South Africa after refueling in the UK capital. Before taking off again and winding up back in SFO, it soared over the northern part of the South Pole and landed in New Zealand. The Boeing 747SP's total flight time was 54 hours, 7 minutes, and 12 seconds, and it cruised at 43,000 feet (13,100 meters) above and around the globe.

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The Reasons behind the Boeing 747SP

A shortened variant of the Boeing 747 widebody airliner, the Boeing 747SP (Special Performance), was designed with a longer range in mind. To compete with the DC-10 and L-1011 trijet widebodies, introduced in 1971 and 1972, Boeing wanted a smaller aircraft capable of covering longer distances.

However, the idea for the Boeing 747SP came from Pan Am in 1973 with a proposal for a Boeing 747 variant capable of carrying a full payload non-stop on its longest route between New York and Tehran. Iran Air (IR) was also in on Pan Am's request; their mutual interest was for a high-capacity airliner capable of covering the New York-Middle Eastern routes of Pan Am and the proposed New York-Tehran route of IR.

On February 4, 1976, the SP version, which first flew on July 4, 1975, was approved by the FAA and entered service with Pan Am that year.

In terms of its defining features, the Boeing 747SP is 47 feet (14 meters) shorter than all the remaining 747 models. To compensate for this, Boeing reduced its main deck doors to four on each side. In addition, the wing flaps have simplified and increased the size of the vertical and horizontal tailplanes. With a 700,000 lb (320 t) MTOW, it can fly 276 passengers over 5,830 nm (10,800 km) in three classes.

In 1987, the last 747SP was delivered, while others were converted to head-of-state transport. Alas, as sales did not achieve Boeing's planned 200 units, only 45 aircraft were ever produced.

One notable use of the type is its repurposing as the aircraft for the Stratospheric Observatory for Infrared Astronomy (SOFIA).

The Flight Around the World

Before Flight 50, Pan Am had flown its Boeing 747SP Clipper 200 'Liberty Bell Express' the previous year to celebrate the US bicentennial on a world record-breaking round at the equator. 98 passengers were carried on the flight, which cost US$2,912 for first-class seats and US$1,838 for Economy.

Pan Am decided to celebrate the company's 50th anniversary with the same model, but this time flying it from pole to pole and around the world. The flight would have as guests Miss USA and Miss Universe. Miss England would join Miss South Africa when stopping in London and Cape Town, and when stopping in Auckland, Miss New Zealand would join the flight en route.

There were 165 first-class passengers, showered with Pan Am's 50th-anniversary gifts and souvenirs. The flight crew was hand-picked, 14 meals were carefully prepared, and classic films were shown.

The bicentennial flight was so popular that some who took it came back for Flight 50, which was even advertised in The Wall Street Journal. Within three days, all the seats were sold. Passengers were willing to spend US$2,200 for a weekend to travel around the world and, in the process, become part of aviation history.

Featured Image: Clipper New Horizons N533PA at JFK in 1977. The 747SP served long-haul routes such as New York to Tokyo. Photo: Pan Am via Twitter. Article sources: Pan Am, CNN, Airliners.net.