Cruise is the phase of aircraft flight that starts when the aircraft levels off after a climb , until it begins to descend for landing. Cruising usually comprises the majority of a flight, and may include small changes in heading (direction of flight), airspeed , and altitude .
26-662: Friendship One was a successful attempt at beating the round-the-world air speed record. The flight was conducted from January 29 to January 30, 1988, and was operated by a Boeing 747SP owned by United Airlines. A charitable foundation, the Friendship Foundation , was established and all money went to children's charities. A ticket on the flight cost USD $ 5,000, and, in total, the flight raised about $ 500,000. A total of 141 passengers were on board, including Neil Armstrong and Bill Lear 's widow, Moya . The previous speed record of 45 hours, 26 minutes, and 55 seconds
52-551: A 700,000-pound (320 t; 320,000 kg) maximum take-off weight, it can fly 276 passengers in three classes over 5,830 nautical miles [nmi] (10,800 km; 6,710 mi). One 747SP was modified into the Stratospheric Observatory for Infrared Astronomy (SOFIA). The last example was delivered in 1987; some were converted to transports of heads of state . Sales did not meet the expected 200 units, and only 45 aircraft were ultimately produced. The idea for
78-437: A higher ECON speed. Cost index can be given in "Boeing" or "English" units as ($ /hr)/(cents/lb) , equivalent to 100 lb/hr . A typical cost index in these units might be anywhere from 5 to 150. Alternatively cost index can be given in metric or "Airbus" units of kg/min . In the presence of a tailwind, ECON airspeed can be reduced to take advantage of the tailwind, whereas in a headwind, ECON speed will be increased to avoid
104-444: A specially modified 747SP was used as the Stratospheric Observatory for Infrared Astronomy (SOFIA) astronomical observatory, operated jointly by NASA and Germany's DLR . A former Pan Am and United Airlines aircraft acquired in 1997, its airframe was modified to carry a 2.5-meter-diameter reflecting telescope to high altitude, above 99.9% of the light-absorbing water vapor in the atmosphere. The telescope and its detectors covered
130-407: A taller vertical tail to counteract the decrease in yaw moment-arm from the shortened fuselage. The 747SP uses single-piece flaps on the trailing edges , rather than the smaller triple-slotted flaps of standard 747s. The SP could accommodate 230 passengers in a 3-class cabin or 331 (303 economy, 28 business) in a 2-class cabin, and a maximum of 400 passengers in one class. From 2007 until 2022,
156-421: A wide wavelength range from the near infrared to the sub-millimeter region; no window material is transparent over this whole range, so the observations were made through a 13 feet (4.0 m) square hole in the port upper quarter of the rear fuselage, aft of a new pressure bulkhead. A sliding door covered the aperture when the telescope was not in use. Astronomers took data and control the instrument from within
182-416: Is 31,000 to 38,000 feet (9,400 to 11,600 m ; 5.9 to 7.2 mi ). The speed which covers the greatest distance for a given amount of fuel is known as the maximum range speed. This is the speed at which drag is minimised. For jet aircraft, "long-range cruise" speed (LRC) is defined as the speed which gives 99% of the maximum range, for a given weight. This results in a 3–5% increase in speed. It
208-560: Is a shortened version of the Boeing 747 wide-body airliner, designed for a longer range . It is the highest flying subsonic passenger airliner , with a service ceiling of 45,100 feet (13,700 m). Boeing needed a smaller aircraft to compete with the McDonnell Douglas DC-10 and Lockheed L-1011 TriStar tri-jet wide-bodies, introduced in 1971/1972. Pan Am requested a 747-100 derivative to fly between New York and
234-400: Is also a more stable speed than maximum range speed, so gives less autothrottle movement. However, LRC speed does not take account of winds, or time-related costs other than fuel, so it has little practical value. Instead, the speed for most economical operation (ECON) is adjusted for wind and the cost index (CI), which is the ratio of time cost to fuel cost. A higher cost index results in
260-497: Is lower. For propeller aircraft, drag is minimised when the lift-to-drag ratio is maximised. However, the speed for this is typically regarded as too slow, so propeller aircraft typically cruise at a significantly faster speed. Combustion engines have an optimum efficiency level for fuel consumption and power output. Generally, gasoline piston engines are most efficient between idle speed and 30% short of full throttle. Diesels are most efficient at around 90% of full throttle. As
286-545: Is usually where the higher ground speed is balanced against the decrease in engine thrust and efficiency at higher altitudes. Common narrowbodies like the Airbus A320 and Boeing 737NG cruise at Mach 0.78 (450 kn; 830 km/h), while modern widebodies like the Airbus A350 and Boeing 787 cruise at Mach 0.85 (490 kn; 900 km/h). The typical cruising altitude for commercial airliners
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#1732782831388312-713: The Middle East , a request also shared by Iran Air , and the first order came from Pan Am in 1973. The variant first flew on July 4, 1975, was approved by the Federal Aviation Administration on February 4, 1976, and entered service that year with Pan Am. The SP is 184 feet 9 inches (56.31 m) in length, 47 feet (14 m) shorter than the original 747 variants. Its main deck doors are reduced to four on each side to suit its lower capacity. The vertical and horizontal tailplanes are larger and its wing flaps have been simplified. With
338-431: The 747SP came from a request by Pan Am for a 747 variant capable of carrying a full payload non-stop on its longest route between New York and Tehran . Joined with Pan Am's request was Iran Air ; their joint interest was for a high-capacity airliner capable of covering Pan Am's New York–Middle Eastern routes and Iran Air's planned New York-Tehran route (New York to Tehran was the longest non-stop commercial flight in
364-400: The aircraft consumes fuel, its weight decreases and the optimum altitude for fuel economy increases. For traffic control reasons it is usually necessary for an aircraft to stay at a cleared flight level . On long-haul flights, the pilot may ask air traffic control to climb from one flight level to a higher one, in a manoeuvre known as a step climb . This aviation -related article is
390-436: The arrival of the 767 , Boeing lacked a mid-sized wide-body to compete in this segment. The second market requirement was an aircraft suitable for the ultra-long-range routes emerging in the mid-1970s following the joint request. These routes needed not only longer range but also higher cruising speeds . Boeing could not afford to develop an all-new design, instead opting to shorten the 747 and optimize it for speed and range, at
416-476: The expense of capacity. Originally designated 747SB for "short body", it was later nicknamed "Sutter's balloon" by employees after 747 chief engineer Joe Sutter . Boeing later changed the production designation to 747SP for "special performance", reflecting the aircraft's greater range and higher cruising speed. Production of the 747SP ran from 1976 to 1983. However, a VIP order for UAE's Abu Dhabi Amiri Flight led Boeing to produce one last SP in 1987. Pan Am
442-472: The last 747SP in commercial service was withdrawn from service after 40 years by Iran Air . In 2020, the last aircraft in governmental use was stored by the Royal Flight of Oman. This list also includes organizations that used the aircraft temporarily, besides main operators. There were three significant commercial around-the-world record-setting flights flown by 747SP: two operated by Pan Am and
468-516: The mid-1970s to early 1980s, the SP's heavy wings, high cost, and reduced capacity, and the increased ranges of forthcoming airliners were some of the many factors that contributed to its low sales. Only 45 were built, and, of those remaining, most are used by operators in the Middle East. However, some of the engineering work on the 747SP was reused with the development of the 747-300 . In the 747SP,
494-675: The normally pressurized cabin. Originally delivered to Pan Am and named "Clipper Lindbergh", the name was displayed in script on the port side of the aircraft. In September 2022, SOFIA ceased operations after the conclusion of its final mission. The retirement was made both on the grounds of cost and suitability for the requirements of the decade to come. The aircraft was later flown to the Pima Air & Space Museum in Tucson , Arizona , to be put on public display. Forty-five 747SP aircraft were built between 1974 and 1987. The production line
520-641: The other operated by United Airlines with the aircraft being "loaned" to Friendship Foundation, in order to raise money for the foundation. Those flights are: Note Related development Aircraft of comparable role, configuration, and era Related lists [REDACTED] Media related to Boeing 747SP at Wikimedia Commons Cruising speed Commercial or passenger aircraft are usually designed for optimum performance around their cruise speed ( V C ) and cruise altitude. Factors affecting optimum cruise speed and altitude include payload, center of gravity , air temperature, and humidity. Cruise altitude
546-450: The penalty of the headwind. In the presence of a tailwind, LRC speed may give a higher fuel burn than ECON. As the aircraft consumes fuel, its weight decreases and the ECON speed decreases. This is because a heavier aircraft should fly faster to generate the required lift at the most efficient lift coefficient . ECON speed will also be higher at higher altitudes because the density of the air
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#1732782831388572-414: The upper deck begins over the section of fuselage that contains the wing box, not ahead of the wing box (as is the case with the 747-100 and 747-200 ). This same design was used in the 747-300 and newer 747-400, resulting in a stretched upper deck. Apart from having a significantly shorter fuselage and one fewer cabin door per side, the 747SP differs from other 747 variants in having simplified flaps and
598-455: The world for a short time). The aircraft was launched with Pan Am's first order in 1973, and the first example was delivered in 1976. A shorter derivative of the 747-100, the SP was developed to target two market requirements. The first was a need to compete with the DC-10 and L-1011 while maintaining commonality with the 747, which in its standard form was too large for many routes. Until
624-494: Was ended in 1982 but reopened in 1987 to fulfill an order for the Abu Dhabi Amiri Flight. As of June 2024 , there are just two Boeing 747SPs remaining in active service, both operating as testbed aircraft for engine manufacturer Pratt & Whitney Canada . Eighteen more aircraft are stored or otherwise preserved. The remaining aircraft were either scrapped, otherwise destroyed, or abandoned. In 2016,
650-538: Was set by a Gulfstream III business jet. Friendship One, captained by Clay Lacy , followed a 23,125-mile route from Seattle, Washington to refueling stops in Athens and Taipei , and back to Seattle. It completed the trip in 36 hours, 54 minutes, and 15 seconds. Later in 1988, a Gulfstream IV made a similar eastbound circumnavigation in 36 hours, 8 minutes, which stands as the world record as of 2013. Boeing 747SP The Boeing 747SP (for Special Performance )
676-421: Was the launch customer for the 747SP, taking the first delivery, Clipper Freedom , on March 5, 1976. Pan Am then made the first flight of the 747SP on April 25, 1976, making a nonstop flight from New York to Tokyo. The 747SP was the longest-range airliner available until the 747-400 entered service in 1989. Despite its technical achievements, the SP never sold as well as Boeing hoped. Increased fuel prices in
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