Cabin pressurization
Cabin pressurization is a process in which conditioned air is pumped into the
The first experimental pressurization systems saw use during the 1920s and 1930s. In the 1940s,
Certain aircraft have unusual pressurization needs. For example, the supersonic airliner Concorde had a particularly high pressure differential due to flying at unusually high altitude: up to 60,000 ft (18,288 m) while maintaining a cabin altitude of 6,000 ft (1,829 m). This increased airframe weight and saw the use of smaller cabin windows intended to slow the decompression rate if a depressurization event occurred.
The
Need for cabin pressurization
Pressurization becomes increasingly necessary at altitudes above 10,000 ft (3,048 m) above sea level to protect crew and passengers from the risk of a number of physiological problems caused by the low outside air pressure above that altitude. For private aircraft operating in the US, crew members are required to use oxygen masks if the cabin altitude (a representation of the air pressure, see below) stays above 12,500 ft (3,810 m) for more than 30 minutes, or if the cabin altitude reaches 14,000 ft (4,267 m) at any time. At altitudes above 15,000 ft (4,572 m), passengers are required to be provided oxygen masks as well. On commercial aircraft, the cabin altitude must be maintained at 8,000 ft (2,438 m) or less. Pressurization of the cargo hold is also required to prevent damage to pressure-sensitive goods that might leak, expand, burst or be crushed on re-pressurization.[citation needed] The principal physiological problems are listed below[citation needed].
- Hypoxia
- The lower partial pressure of oxygen at high altitude reduces the alveolar oxygen tension in the lungs and subsequently in the brain, leading to sluggish thinking, dimmed vision, loss of consciousness, and ultimately death[citation needed]. In some individuals, particularly those with heart or lung disease, symptoms may begin as low as 5,000 ft (1,524 m), although most passengers can tolerate altitudes of 8,000 ft (2,438 m) without ill effect. At this altitude, there is about 25% less oxygen than there is at sea level.[5]
- Hypoxia may be addressed by the administration of supplemental oxygen, either through an partial oxygen pressure to function normally and that pressure can be maintained up to about 40,000 ft (12,192 m) by increasing the mole fraction of oxygen in the air that is being breathed. At 40,000 ft (12,192 m), the ambient air pressure falls to about 0.2 bar, at which maintaining a minimum partial pressure of oxygen of 0.2 bar requires breathing 100% oxygen using an oxygen mask.
- Emergency oxygen supply masks in the passenger compartment of airliners do not need to be pressure-demand masks because most flights stay below 40,000 ft (12,192 m). Above that altitude the partial pressure of oxygen will fall below 0.2 bar even at 100% oxygen and some degree of cabin pressurization or rapid descent will be essential to avoid the risk of hypoxia.
- Altitude sickness
- Hyperventilation, the body's most common response to hypoxia, does help to partially restore the partial pressure of oxygen in the blood, but it also causes carbon dioxide (CO2) to out-gas, raising the blood pH and inducing alkalosis. Passengers may experience fatigue, nausea, headaches, sleeplessness, and (on extended flights) even pulmonary edema. These are the same symptoms that mountain climbers experience, but the limited duration of powered flight makes the development of pulmonary oedema unlikely. Altitude sickness may be controlled by a full pressure suit with helmet and faceplate, which completely envelops the body in a pressurized environment; however, this is impractical for commercial passengers.
- Decompression sickness
- The low partial pressure of gases, principally nitrogen (N2) but including all other gases, may cause dissolved gases in the bloodstream to precipitate out, resulting in gas embolism, or bubbles in the bloodstream. The mechanism is the same as that of compressed-air divers on ascent from depth. Symptoms may include the early symptoms of "the bends"—tiredness, forgetfulness, headache, stroke, thrombosis, and subcutaneous itching—but rarely the full symptoms thereof. Decompression sickness may also be controlled by a full-pressure suit as for altitude sickness.
- Barotrauma
- As the aircraft climbs or descends, passengers may experience discomfort or acute pain as gases trapped within their bodies expand or contract. The most common problems occur with air trapped in the gastrointestinal tract or even the teeth (barodontalgia). Usually these are not severe enough to cause actual trauma but can result in soreness in the ear that persists after the flight[6] and can exacerbate or precipitate pre-existing medical conditions, such as pneumothorax.
Cabin altitude
The pressure inside the cabin is technically referred to as the equivalent effective cabin altitude or more commonly as the cabin altitude. This is defined as the equivalent altitude above mean sea level having the same atmospheric pressure according to a standard atmospheric model such as the International Standard Atmosphere. Thus a cabin altitude of zero would have the pressure found at mean sea level, which is taken to be 101.325 kPa (14.696 psi).[7]
Aircraft
In airliners, cabin altitude during flight is kept above sea level in order to reduce stress on the pressurized part of the fuselage; this stress is proportional to the difference in pressure inside and outside the cabin. In a typical commercial passenger flight, the cabin altitude is programmed to rise gradually from the altitude of the airport of origin to a regulatory maximum of 8,000 ft (2,438 m). This cabin altitude is maintained while the aircraft is cruising at its maximum altitude and then reduced gradually during descent until the cabin pressure matches the ambient air pressure at the destination.[citation needed]
Keeping the cabin altitude below 8,000 ft (2,438 m) generally prevents significant
The cabin altitude of the
Before 1996, approximately 6,000 large commercial transport airplanes were assigned a type certificate to fly up to 45,000 ft (13,716 m) without having to meet high-altitude special conditions.[19] In 1996, the FAA adopted Amendment 25-87, which imposed additional high-altitude cabin pressure specifications for new-type aircraft designs. Aircraft certified to operate above 25,000 ft (7,620 m) "must be designed so that occupants will not be exposed to cabin pressure altitudes in excess of 15,000 ft (4,572 m) after any probable failure condition in the pressurization system".[20] In the event of a decompression that results from "any failure condition not shown to be extremely improbable", the plane must be designed such that occupants will not be exposed to a cabin altitude exceeding 25,000 ft (7,620 m) for more than 2 minutes, nor to an altitude exceeding 40,000 ft (12,192 m) at any time.[20] In practice, that new Federal Aviation Regulations amendment imposes an operational ceiling of 40,000 ft (12,000 m) on the majority of newly designed commercial aircraft.[21][22] Aircraft manufacturers can apply for a relaxation of this rule if the circumstances warrant it. In 2004, Airbus acquired an FAA exemption to allow the cabin altitude of the A380 to reach 43,000 ft (13,106 m) in the event of a decompression incident and to exceed 40,000 ft (12,192 m) for one minute. This allows the A380 to operate at a higher altitude than other newly designed civilian aircraft.[21]
Spacecraft
Russian engineers used an air-like nitrogen/oxygen mixture, kept at a cabin altitude near zero at all times, in their 1961 Vostok, 1964 Voskhod, and 1967 to present Soyuz spacecraft.[23] This requires a heavier space vehicle design, because the spacecraft cabin structure must withstand the stress of 14.7 pounds per square inch (1 atm, 1.01 bar) against the vacuum of space, and also because an inert nitrogen mass must be carried. Care must also be taken to avoid decompression sickness when cosmonauts perform extravehicular activity, as current soft space suits are pressurized with pure oxygen at relatively low pressure in order to provide reasonable flexibility.[24]
By contrast, the United States used a pure oxygen atmosphere for its 1961
After the Apollo program, the United States used "a 74-percent oxygen and 26-percent nitrogen breathing mixture" at 5 psi (0.34 bar) for Skylab,[31] and a standard air-like[vague] cabin atmosphere for the Space Shuttle orbiter and the International Space Station.[32]
Mechanics
An airtight fuselage is pressurized using a source of compressed air and controlled by an environmental control system (ECS). The most common source of compressed air for pressurization is bleed air from the compressor stage of a gas turbine engine; from a low or intermediate stage or an additional high stage, the exact stage depending on engine type. By the time the cold outside air has reached the bleed air valves, it has been heated to around 200 °C (392 °F). The control and selection of high or low bleed sources is fully automatic and is governed by the needs of various pneumatic systems at various stages of flight. Piston-engine aircraft require an additional compressor, see diagram right.[34]
The part of the bleed air that is directed to the ECS is then expanded to bring it to cabin pressure, which cools it. A final, suitable temperature is then achieved by adding back heat from the hot compressed air via a heat exchanger and air cycle machine known as a PAC (Pressurization and Air Conditioning) system. In some larger airliners, hot trim air can be added downstream of air-conditioned air coming from the packs if it is needed to warm a section of the cabin that is colder than others.
At least two engines provide compressed bleed air for all the plane's pneumatic systems, to provide full redundancy. Compressed air is also obtained from the auxiliary power unit (APU), if fitted, in the event of an emergency and for cabin air supply on the ground before the main engines are started. Most modern commercial aircraft today have fully redundant, duplicated electronic controllers for maintaining pressurization along with a manual back-up control system.
All exhaust air is dumped to atmosphere via an outflow valve, usually at the rear of the fuselage. This valve controls the cabin pressure and also acts as a safety relief valve, in addition to other safety relief valves. If the automatic pressure controllers fail, the pilot can manually control the cabin pressure valve, according to the backup emergency procedure checklist. The automatic controller normally maintains the proper cabin pressure altitude by constantly adjusting the outflow valve position so that the cabin altitude is as low as practical without exceeding the maximum pressure differential limit on the fuselage. The pressure differential varies between aircraft types, typical values are between 540 hPa (7.8 psi) and 650 hPa (9.4 psi).[35] At 39,000 ft (11,887 m), the cabin pressure would be automatically maintained at about 6,900 ft (2,100 m), (450 ft (140 m) lower than Mexico City), which is about 790 hPa (11.5 psi) of atmosphere pressure.[34]
Some aircraft, such as the Boeing 787 Dreamliner, have re-introduced electric compressors previously used on piston-engined airliners to provide pressurization.[36][37] The use of electric compressors increases the electrical generation load on the engines and introduces a number of stages of energy transfer;[38] therefore, it is unclear whether this increases the overall efficiency of the aircraft air handling system. They do, however, remove the danger of chemical contamination of the cabin, simplify engine design, avert the need to run high pressure pipework around the aircraft, and provide greater design flexibility.
Unplanned decompression
Unplanned loss of cabin pressure at altitude/in space is rare but has resulted in a number of fatal accidents. Failures range from sudden, catastrophic loss of airframe integrity (explosive decompression) to slow leaks or equipment malfunctions that allow cabin pressure to drop.
Any failure of cabin pressurization above 10,000 ft (3,048 m) requires an emergency descent to 8,000 ft (2,438 m) or the closest to that while maintaining the minimum sector altitude (MSA), and the deployment of an
For airliners that need to fly over terrain that does not allow reaching the safe altitude within a maximum of 30 minutes, pressurized oxygen bottles are mandatory since the
In
On June 30, 1971, the crew of Soyuz 11, Soviet cosmonauts Georgy Dobrovolsky, Vladislav Volkov, and Viktor Patsayev were killed after the cabin vent valve accidentally opened before atmospheric re-entry.[40][41]
History
The aircraft that pioneered pressurized cabin systems include:
- Packard-Le Père LUSAC-11, (1920, a modified French design, not actually pressurized but with an enclosed, oxygen enriched cockpit)
- Engineering Division USD-9A, a modified Airco DH.9A (1921 – the first aircraft to fly with the addition of a pressurized cockpit module)[42]
- Junkers Ju 49 (1931 – a German experimental aircraft purpose-built to test the concept of cabin pressurization)
- Farman F.1000 (1932 – a French record breaking pressurized cockpit, experimental aircraft)
- Chizhevski BOK-1 (1936 – a Russian experimental aircraft)
- Lockheed XC-35 (1937 – an American pressurized aircraft. Rather than a pressure capsule enclosing the cockpit, the monocoque fuselage skin was the pressure vessel.)
- Renard R.35 (1938 – the first pressurized piston airliner)
- Boeing 307 Stratoliner (1938 – the first pressurized airliner to enter commercial service)
- Lockheed Constellation (1943 – the first pressurized airliner in wide service)
- Avro Tudor (1946 – first British pressurized airliner)
- de Havilland Comet (British, Comet 1 1949 – the first jetliner, Comet 4 1958 – resolving the Comet 1 problems)
- Tupolev Tu-144 and Concorde (1968 USSR and 1969 Anglo-French respectively – first to operate at very high altitude)
- Cessna P210 (1978) First commercially successful pressurized single-engine aircraft[43]
- SyberJet SJ30 (2005) First civilian business jet to certify 12.0 psi pressurization system allowing for a sea level cabin at 41,000 ft (12,497 m).
In the late 1910s, attempts were being made to achieve higher and higher altitudes. In 1920, flights well over 37,000 ft (11,278 m) were first achieved by test pilot Lt. John A. Macready in a Packard-Le Père LUSAC-11 biplane at McCook Field in Dayton, Ohio.[44] The flight was possible by releasing stored oxygen into the cockpit, which was released directly into an enclosed cabin and not to an oxygen mask, which was developed later.[44] With this system flights nearing 40,000 ft (12,192 m) were possible, but the lack of atmospheric pressure at that altitude caused the pilot's heart to enlarge visibly, and many pilots reported health problems from such high altitude flights.[44] Some early airliners had oxygen masks for the passengers for routine flights.
In 1921, a Wright-Dayton USD-9A reconnaissance biplane was modified with the addition of a completely enclosed air-tight chamber that could be pressurized with air forced into it by small external turbines.[44] The chamber had a hatch only 22 in (560 mm) in diameter that would be sealed by the pilot at 3,000 ft (914 m).[44] The chamber contained only one instrument, an altimeter, while the conventional cockpit instruments were all mounted outside the chamber, visible through five small portholes.[44] The first attempt to operate the aircraft was again made by Lt. John A. McCready, who discovered that the turbine was forcing air into the chamber faster than the small release valve provided could release it.[44] As a result, the chamber quickly over pressurized, and the flight was abandoned.[44] A second attempt had to be abandoned when the pilot discovered at 3,000 ft (914 m) that he was too short to close the chamber hatch.[44] The first successful flight was finally made by test pilot Lt. Harrold Harris, making it the world's first flight by a pressurized aircraft.[44]
The first airliner to enter commercial service with a pressurized cabin was the Boeing 307 Stratoliner, built in 1938, prior to World War II, though only ten were produced before the war interrupted production. The 307's "pressure compartment was from the nose of the aircraft to a pressure bulkhead in the aft just forward of the horizontal stabilizer."[45]
World War II was a catalyst for aircraft development. Initially, the piston aircraft of World War II, though they often flew at very high altitudes, were not pressurized and relied on oxygen masks.[46] This became impractical with the development of larger bombers where crew were required to move about the cabin and this led to the first bomber with cabin pressurization (though restricted to crew areas), the Boeing B-29 Superfortress. The control system for this was designed by Garrett AiResearch Manufacturing Company, drawing in part on licensing of patents held by Boeing for the Stratoliner.[47]
Post-war piston airliners such as the Lockheed Constellation (1943) made the technology more common in civilian service. The piston-engined airliners generally relied on electrical compressors to provide pressurized cabin air. Engine supercharging and cabin pressurization enabled aircraft like the Douglas DC-6, the Douglas DC-7, and the Constellation to have certified service ceilings from 24,000 to 28,400 ft (7,315 to 8,656 m). Designing a pressurized fuselage to cope with that altitude range was within the engineering and metallurgical knowledge of that time. The introduction of jet airliners required a significant increase in cruise altitudes to the 30,000–41,000 ft (9,144–12,497 m) range, where jet engines are more fuel efficient. That increase in cruise altitudes required far more rigorous engineering of the fuselage, and in the beginning not all the engineering problems were fully understood.
The world's first commercial jet airliner was the British
The critical engineering principles concerning metal fatigue learned from the Comet 1 program[48] were applied directly to the design of the Boeing 707 (1957) and all subsequent jet airliners. For example, detailed routine inspection processes were introduced, in addition to thorough visual inspections of the outer skin, mandatory structural sampling was routinely conducted by operators; the need to inspect areas not easily viewable by the naked eye led to the introduction of widespread radiography examination in aviation; this also had the advantage of detecting cracks and flaws too small to be seen otherwise.[49] Another visibly noticeable legacy of the Comet disasters is the oval windows on every jet airliner; the metal fatigue cracks that destroyed the Comets were initiated by the small radius corners on the Comet 1's almost square windows.[50][51] The Comet fuselage was redesigned and the Comet 4 (1958) went on to become a successful airliner, pioneering the first transatlantic jet service, but the program never really recovered from these disasters and was overtaken by the Boeing 707.[52][53]
Even following the Comet disasters, there were several subsequent catastrophic fatigue failures attributed to cabin pressurisation. Perhaps the most prominent example was
The supersonic airliner Concorde had to deal with particularly high pressure differentials because it flew at unusually high altitude (up to 60,000 ft (18,288 m)) and maintained a cabin altitude of 6,000 ft (1,829 m).[57] Despite this, its cabin altitude was intentionally maintained at 6,000 ft (1,829 m).[58] This combination, while providing for increasing comfort, necessitated making Concorde a significantly heavier aircraft, which in turn contributed to the relatively high cost of a flight. Unusually, Concorde was provisioned with smaller cabin windows than most other commercial passenger aircraft in order to slow the rate of decompression in the event of a window seal failing.[59] The high cruising altitude also required the use of high pressure oxygen and demand valves at the emergency masks unlike the continuous-flow masks used in conventional airliners.[60] The FAA, which enforces minimum emergency descent rates for aircraft, determined that, in relation to Concorde's higher operating altitude, the best response to a pressure loss incident would be to perform a rapid descent.[61]
The designed operating cabin altitude for new aircraft is falling and this is expected to reduce any remaining physiological problems. Both the
See also
- Aerotoxic syndrome
- Air cycle machine
- Atmosphere (unit)
- Compressed air
- Fume event
- Rarefaction
- Space suit
- Time of useful consciousness
Footnotes
- ^ Brain, Marshall (April 12, 2011). "How Airplane Cabin Pressurization Works". How Stuff Works. Archived from the original on January 15, 2013. Retrieved December 31, 2012.
- ^ "Why do aircraft use cabin pressurization". aerospace.honeywell.com. Retrieved 2022-08-24.
- ^ a b rmjg20 (2012-06-09). "The DeHavilland Comet Crash". Aerospace Engineering Blog. Archived from the original on 2022-09-10. Retrieved 2022-08-26.
{{cite web}}
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- ^ K. Baillie and A. Simpson. "Altitude oxygen calculator". Retrieved 2006-08-13. – Online interactive altitude oxygen calculator
- Harvard Health Publishing. Harvard Medical School. December 2018. Retrieved 2019-04-14.
On an airplane, barotrauma to the ear – also called aero-otitis or barotitis – can happen as the plane descends for landing.
- ^ Auld, D. J.; Srinivas, K. (2008). "Properties of the Atmosphere". Archived from the original on 2013-06-09. Retrieved 2008-03-13.
- ^ "Chapter 7: Aircraft Systems". Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25B ed.). Federal Aviation Administration. 2016-08-24. p. 36. Archived from the original on 2023-06-20.
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- ^ "Commercial Airliner Environmental Control System: Engineering Aspects of Cabin Air Quality" (PDF). Archived from the original (PDF) on 2011-05-24.
- ^ "Manufacturers aim for more comfortable cabin climate". Flightglobal. 19 Mar 2012.
- ^ "Bombardier's Stretching Range on Global Express Global Express XRS". Aero-News Network. October 7, 2003.
- ^ "Bombardier Global Express XRS Factsheet" (PDF). Bombardier. 2011. Archived from the original (PDF) on 2010-02-16. Retrieved 2012-01-09.
- ^ "Aircraft Environmental Control Systems" (PDF). Carleton University. 2003.
- ^ Flight Test: Emivest SJ30 – Long-range rocket Retrieved 27 September 2012.
- ^ SJ30-2, United States of America Retrieved 27 September 2012.
- ^ "Airlines are cutting costs – Are patients with respiratory diseases paying the price?". European Respiratory Society. 2010.
- ^ "Final Policy FAR Part 25 Sec. 25.841 07/05/1996|Attachment 4".
- ^ a b "FARs, 14 CFR, Part 25, Section 841".
- ^ a b "Exemption No. 8695". Renton, Washington: Federal Aviation Administration. 2006-03-24. Archived from the original on 2009-03-27. Retrieved 2008-10-02.
- ^ Steve Happenny (2006-03-24). "PS-ANM-03-112-16". Federal Aviation Administration. Retrieved 2009-09-23.
- ^ Gatland, Kenneth (1976). Manned Spacecraft (Second ed.). New York: MacMillan. p. 256.
- ^ Gatland, p. 134
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- ^ Giblin, Kelly A. (Spring 1998). "Fire in the Cockpit!". American Heritage of Invention & Technology. 13 (4). Archived from the original on November 20, 2008. Retrieved March 23, 2011.
- ^ Gatland, p. 264
- ^ Gatland, p. 269
- ^ Gatland, p. 278, 284
- ^ "The Apollo 1 Fire –".
- ^ Belew, Leland F., ed. (1977). "2. Our First Space Station". SP-400 Skylab: Our First Space Station. Washington DC: NASA. p. 18. Retrieved July 15, 2019.
- ^ 1 atm
- ^ "Chapter 7: Aircraft Systems". Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25B ed.). Federal Aviation Administration. 2016-08-24. pp. 34–35. Archived from the original on 2023-06-20.
- ^ a b "Commercial Airliner Environmental Control System: Engineering Aspects of Cabin Air". 1995. Archived from the original (PDF) on 31 March 2012.
- ^ "Differential Pressure Characteristics of Aircraft".
- ^ Ogando, Joseph, ed. (June 4, 2007). "Boeing's 'More Electric' 787 Dreamliner Spurs Engine Evolution: On the 787, Boeing eliminated bleed air and relied heavily on electric starter generators". Design News. Archived from the original on April 6, 2012. Retrieved September 9, 2011.
- ^ Dornheim, Michael (March 27, 2005). "Massive 787 Electrical System Pressurizes Cabin". Aviation Week & Space Technology.
- ^ "Boeing 787 from the Ground Up"
- ^ Jedick MD/MBA, Rocky (28 April 2013). "Hypoxia". goflightmedicine.com. Go Flight Medicine. Retrieved 17 March 2014.
- ^ "Triumph and Tragedy of Soyuz 11". Time. 12 July 1971. Archived from the original on March 18, 2008. Retrieved 20 October 2007.
- ^ "Soyuz 11". Encyclopedia Astronautica. 2007. Archived from the original on 30 October 2007. Retrieved 20 October 2007.
- ^ Harris, Brigader General Harold R. USAF (Ret.), “Sixty Years of Aviation History, One Man's Remembrance,” journal of the American Aviation Historical Society, Winter, 1986, p 272-273
- ^ New, Paul (May 17, 2018). "All Blown Up". Tennessee Aircraft Services. Retrieved 21 May 2021.
The P210 wasn't the first production pressurized single engine aircraft, but it was definitely the first successful one.
- ^ ISBN 0-16-067599-5.
- ISBN 0-9617029-0-7), p. 275.
- ^ Some extremely high flying aircraft such as the Westland Welkin used partial pressurization to reduce the effort of using an oxygen mask.
- JSTOR 3636792.
- CiteSeerX 10.1.1.226.7667.
- ^ Jefford, C.G., ed. The RAF and Nuclear Weapons, 1960–1998. London: Royal Air Force Historical Society, 2001. pp. 123–125.
- ISBN 1-888962-14-3. pp. 30–31.
- ^ Munson, Kenneth. Civil Airliners since 1946. London: Blandford Press, 1967. p. 155.
- ^ "Milestones in Aircraft Structural Integrity". ResearchGate. Retrieved 22 March 2019.
- ISBN 0-7522-2118-3. p. 72.
- NTSB. 14 June 1989.
- ^ Aloha Airlines Flight 243 incident report - AviationSafety.net, accessed July 5, 2014.
- ^ a b "Aircraft Accident Report, Aloha Airlines Flight 243, Boeing 737-100, N73711, Near Maui, Hawaii, April 28, 1998" (PDF). National Transportation Safety Board. June 14, 1989. NTSB/AAR-89/03. Retrieved February 5, 2016.
- .
- .
- ISBN 0-7506-1336-X.
- ^ Nunn 1993, p. 341.
- ^ Happenny, Steve (24 March 2006). "Interim Policy on High Altitude Cabin Decompression – Relevant Past Practice". Federal Aviation Administration.
- ^ a b Adams, Marilyn (November 1, 2006). "Breathe easy, Boeing says". USA Today.
- ^ Croft, John (July 2006). "Airbus and Boeing spar for middleweight" (PDF). American Institute of Aeronautics and Astronautics. Archived from the original (PDF) on July 10, 2007. Retrieved July 8, 2007.
- ^ "Boeing 7E7 Offers Preferred Cabin Environment, Study Finds" (Press release). Boeing. July 19, 2004. Archived from the original on November 6, 2011. Retrieved June 14, 2011.
- ^ "Taking the lead: A350XWB presentation" (PDF). EADS. December 2006. Archived from the original (PDF) on 2009-03-27.
General references
- Seymour L. Chapin (August 1966). "Garrett and Pressurized Flight: A Business Built on Thin Air". Pacific Historical Review. 35 (3): 329–43. JSTOR 3636792.
- Seymour L. Chapin (July 1971). "Patent Interferences and the History of Technology: A High-flying Example". Technology and Culture. 12 (3): 414–46. S2CID 112829106.
- Cornelisse, Diana G. Splendid Vision, Unswerving Purpose; Developing Air Power for the United States Air Force During the First Century of Powered Flight. Wright-Patterson Air Force Base, Ohio: U.S. Air Force Publications, 2002. ISBN 0-16-067599-5. pp. 128–29.
- Portions from the United States Naval Flight Surgeon's Manual
- "121 Dead in Greek Air Crash", CNN