The Boeing 747 has been in service with various commercial and government operators since its introduction in 1970. Historically, it was the primary long-haul aircraft of various airlines until changes in aircraft design trends and industry dynamics led to the gradual phase-out of 747 fleets in passenger operations. Today, the 747 is more commonly used by cargo airlines and government or military branches.
Flight testing Boeing flight test program Certification test flights
The prototype 747, City of Everett (registration serial N7470), made its maiden flight on February 9, 1969, with test pilots Jack Waddell and Brien Wygle, along with flight engineer Jess Wallick, at the controls. The aircraft took off at 11:34 PST (UTC-8) from Paine Field and was flown over the Puget Sound. During this test flight, the City of Everett reached an altitude of and flew at a speed of up to while carrying of instrumentation, as well as of water ballast for weight. The flight went as planned until the pilot of the Boeing-owned F-86 Sabre chase plane reported one of the inboard flap sections was misaligned when the crew tested the handling of the aircraft with full flaps (30 degrees), at which point the crew decided to return to Paine Field. After spending 1 hour and 26 minutes in the air, the City of Everett landed safely without further incident. In their evaluation of the maiden flight, the test pilots asserted that the 747's controls were light and well-balanced, enabling it to fly well on a gusty day with no turbulence, and they also determined that the 747 was immune to the Dutch roll, a phenomenon observed in earlier swept-wing aircraft.
Shortly after the first flight of the City of Everett, Boeing assembled the next four aircraft, which were all 747-100s destined for airline service, for use in the flight test program before delivery to their respective customers. These aircraft consisted of three 747-121s (registration serials N747PA, N731PA, and N732PA) intended for Pan Am and one 747-131 (registration serial N93101) intended for Trans World Airlines (TWA). Production aircraft differed from the prototype by the installation of higher-thrust Pratt & Whitney JT9D-3A engines, whereas the prototype was equipped with the earlier JT9D-1.
N747PA, initially named Jet Clipper America, was the first production aircraft completed. It rolled out of Boeing's Everett plant on February 28, 1969, but did not fly until April 11. N731PA, named Clipper Bostonian, was rolled out 12 days after N747PA's first flight and joined the test program on May 10, while N732PA, named Clipper Storm King, was rolled out on May 16. The time between N732PA’s rollout and first flight was longer than that of its older sister ships due to the installation of a long pole on its nose for gust measurement. N732PA’s first flight was on July 10, three days before that of N93101, the sole TWA 747 in the test program. Boeing assigned N747PA for engines and systems testing, N731PA for structural tests, and N732PA and N93101 for service testing. In their flight test roles, N747PA, N731PA, N732PA, and N93101 were designated Ships 2, 3, 4, and 5, respectively. The City of Everett, which was designated Ship 1 or RA001, was used alongside these aircraft to probe the 747's basic aerodynamics and clear reported issues with flutter.
The test aircraft were pushed to their limits through extreme flight maneuvers, such as stalls and rejected takeoffs, to study the design's handling characteristics. The test aircraft flew at altitudes up to , dived at speeds up to Mach 0.991, and took off at weights of up to .
Unplanned system failures were experienced during the flight tests and sometimes caused damage to the test aircraft. One documented instance occurred on July 21, 1969, when N747PA came to a sudden stop after its automatic brakes failed while it was taxied out of its parking stall on Boeing Field. In an attempt to get the aircraft moving again, the crew applied more power to the engines, causing a nearby wheel-mounted shed to be blown by the jet blast and hit N731PA. The resulting damage to N731PA cost US$5,000.00 (US$ today) and injured four personnel on the ground.
The most serious accident in the flight test program occurred on December 13, 1969, when N732PA, flown by test pilot Ralph Cokely in strong crosswinds, undershot the runway at the Renton Municipal Airport, the site of the Boeing Renton Factory, causing it to crash land, tearing off the right outer landing gear and damaging the right wing's engine nacelles in the process.
On December 31, 1969, the Federal Aviation Administration (FAA) issued the 747's type certificate, clearing it for commercial service. By this time, the five test aircraft had flown 1,449 hours in 1,013 flights, including 539 hours for FAA demonstration flights.
Further testing After the 747's introduction into commercial service in 1970, Boeing continued flight tests to improve the 747's design and address reported issues. In its first year of service, it was observed generating a significant amount of wake turbulence and posed a risk for smaller aircraft flying behind it, prompting the FAA to implement separation rules for aircraft flying close to 747s; the French government banned Pan Am from flying 747s into Paris during its first year of 747 service due to this concern. Boeing addressed these concerns in 1970 by conducting wake turbulence tests with a 737-100 flying closely behind a 747 at various distances to measure the wake generation of the larger aircraft, which Boeing found only to have a slight difference from the wake generated by the smaller 707 flown in the same test.
Boeing primarily focused on payload capabilities during the development and testing of the upgraded 747-200 and its subvariants throughout the 1970s. Weight trials were conducted between October and November of 1970 at Edwards Air Force Base with the prototype 747-200B, a 747-251B intended for Northwest Airlines, which reached a maximum takeoff weight of during a test flight on November 12. At that time, the aircraft held the record for the heaviest takeoff weight until heavier and more powerful 747-200 airframes were built. On November 1, 1976, the first RB211-powered 747-200 set a world record for maximum mass lifted during a trial flight at NAS Lemoore, where it flew up to with a weight of .
Passenger airlines United States Pan Am
From the outset, the 747 was designed based on Pan Am's need for an aircraft times larger than the Boeing 707, the airline's primary long-haul aircraft in the 1960s. As the launch customer of the 747,Rumerman, Judy. "The Boeing 747". U.S. Centennial of Flight Commission, 2003. Retrieved: April 30, 2006.Noland, David. "Passenger Planes: Boeing 747." "Info please" (Pearson Education). Retrieved: April 30, 2006. Pan Am was heavily involved in the development of the 747 to an extent unmatched by a single airline before or since.
Pan Am announced its initial order for 25 747s on April 13, 1966. The first delivery of a 747 to an airline was made on December 12, 1969, when Pan Am received the airframe with registration serial N733PA, originally named Clipper Young America; this aircraft would later switch names with Clipper Constitution (registration serial N735PA) shortly before Pan Am's inaugural 747 service in January 1970. The first three production aircraft that had been assembled earlier in the year were intended for Pan Am but remained in Boeing's flight test program. The three test aircraft (registration serials N731PA, N732PA, N747PA) were eventually delivered between July and October 1970, much later than their younger sister ships.
On January 15, 1970, First Lady Pat Nixon christened Pan Am's first 747 at Dulles International Airport in the presence of Pan Am chairman Najeeb Halaby. Instead of champagne, red, white, and blue water was sprayed on the aircraft.
The 747 entered service on January 22, 1970, on Pan Am's New York–London route. The flight had been planned for the evening of January 21, but engine overheating made the original aircraft (Clipper Young America, registration N735PA) unusable. Finding a substitute delayed the flight by more than six hours to the following day when Clipper Victor (registration N736PA) was used."Jumbo and the Gremlins". Time, February 2, 1970. Retrieved: December 20, 2007. The 747 enjoyed a fairly smooth introduction into service, overcoming concerns that some airports would not be able to accommodate an aircraft that large."Breaking the Ground Barrier". Time, September 8, 1967. Retrieved: December 19, 2007. Although technical problems occurred, they were relatively minor and quickly solved."Jumbo Beats the Gremlins". Time, July 13, 1970. Retrieved: December 20, 2007.
Within the first year of service, Pan Am expanded its network of transatlantic 747 operations to various destinations in Europe, namely Amsterdam, Barcelona, Brussels, Frankfurt, Lisbon, Paris, and Rome, from hubs in New York and London's Heathrow Airport. Transpacific operations from Los Angeles and San Francisco to Honolulu, Hong Kong, and Tokyo were started once sufficient aircraft were delivered to sustain 747 operations on both the transatlantic and transpacific networks. The Los Angeles and San Francisco hubs were connected to London and Paris via polar routes, and Pan Am 747s also flew from Chicago to Frankfurt and London and from New York to San Juan. In recognition of its role in the development and introduction of the 747, Pan Am, along with Boeing and Pratt & Whitney, received the 1970 Collier Trophy, one of the highest honors in the aviation industry.
Beginning in November 1970, Pan Am 747-100s were sent back to the Boeing Everett Factory for refurbishment. The refurbished aircraft were equipped with higher-thrust variants of the Pratt & Whitney JT9D powerplant, specifically the standard JT9D-7/7A and the water-injected JT9D-3AW/7AW, which increased the maximum takeoff weight up to and provided an additional range of . The landing gear, flaps, fuel system, doors, and in-flight entertainment system were also upgraded in the refurbished specification. The upgraded aircraft were internally designated 747-100A within Pan Am to distinguish them from airframes still being operated with the original specifications.
Despite having the longest range out of all commercial airliners in service by the mid-1970s, the performance of the engines on early models of the 747 limited their range. Hence, they could not fly nonstop on routes as long as . When Pan Am requested for an aircraft that could fly its New York–Tokyo route nonstop, Boeing responded by designing the 747SP (Special Performance), which featured higher-thrust engines and a fuselage shorter than that of the -100 and -200 variants. The SP received FAA certification on February 4, 1976, and was introduced by Pan Am on its New York–Tokyo route in April.
In October 1977, Pan Am commemorated its 50th anniversary by flying a 747SP, named Clipper New Horizons (registration serial N533PA), on a round-the-world trip that started and ended in San Francisco. The journey took a transpolar route to London, a flight across the African continent that landed in Cape Town, and a transpolar route across Antarctica to Auckland before its return to the United States. The journey covered in 56 hours and 7 minutes, which broke Pan Am's internal speed record for a round-the-world trip that was previously set 12 years earlier by a modified 707.