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Aircraft emergency oxygen systems or air masks are emergency equipment fitted to pressurized commercial aircraft, intended for use when the cabin pressurisation system has failed and the cabin altitude has climbed above a safe level. It consists of a number of individual yellow oxygen masks stored in compartments near passenger seats and near areas like lavatories and galleys, and an oxygen source, like a centralized gaseous cylinder or decentralized chemical oxygen generator.
Most commercial aircraft that operate at high flight altitudes are pressurized at a maximum cabin altitude of approximately 8,000 feet. On most pressurized aircraft, if cabin pressurization is lost when the aircraft is flying at an altitude above 4,267 m (14,000 feet), compartments containing the oxygen masks will open automatically, either above or in front of the passenger and crew seats, and the oxygen masks will drop down in front of the passenger. Oxygen masks may also drop on extremely rough landings or during severe turbulence if the oxygen mask panel becomes loose. Rows of seats typically have an extra mask (e.g. 3 seats, 4 masks), in case someone has an infant in their lap, or someone in the aisle needs one.[ citation needed ]
An oxygen mask consists of a yellow, soft, silicone facial cup with white elastic bands for securing the mask to the passenger's face. This band is adjustable by pulling two ends looped through the facial cup. The mask may also have a concentrator or re-breather bag that may or may not inflate depending on the cabin altitude, which has (in some instances) made passengers nervous the mask was not providing adequate oxygen, causing some to remove them, who thereby suffered hypoxia. All airlines now make a point in the safety video or demonstration to point out that the bag may not inflate.[ citation needed ] The bag is attached to a tube, connected to the oxygen source in the compartment, allowing for it to drop down and hang in front of the passengers. To operate on all aircraft, they must be pulled sharply toward the user to un-clip the flow pin and start the process of transporting the oxygen to the passenger. Passenger oxygen masks cannot deliver enough oxygen for sustained periods at high altitudes. This is why the flight crew needs to place the aircraft in a controlled emergency descent to a lower altitude where it is possible to breathe without emergency oxygen. While the masks are being used, passengers are not allowed to leave their seat for any reason until it is safe to breathe without the emergency oxygen. If there is a fire on board the aircraft, masks are not deployed, as the production of oxygen may further fuel the fire.
Aircraft safety cards and in-flight safety demonstrations shown at the beginning of each flight explain the location and use of oxygen masks.
Some aircraft, such as the Saab 340/2000 and the Beechcraft 1900D, have a mask system where either a mask is stored under the seat or is distributed by the cabin attendant. These masks are removed from packaging and plugged into the socket for oxygen supply.[ citation needed ]
On the Boeing 777-300ER and Boeing 787, oxygen masks only consist of the mask and tube. Passengers breathe into the mask to start oxygen flow, and there are no side straps, as the mask adjusts automatically.[ clarification needed ][ citation needed ]
Portable oxygen supplies for cabin crew are not a suitable substitute for medically-necessary therapeutic oxygen, even in an emergency, because it does not provide enough oxygen to overcome Dalton's Law.[ clarification needed ] [1]
There are currently three systems that are typically found on aircraft:
Combustion is the exothermic chemical reaction between oxygen and a fuel, producing a flame and smoke. [5] Because an oxidiser is necessary for a fire, oxygen-generating equipment on aircraft pose a significant fire hazard and have contributed to several aircraft fires, both on the ground and while in flight.
Aircraft accidents and incidents related to oxygen supply systems include:
An airliner is a type of airplane for transporting passengers and air cargo. Such aircraft are most often operated by airlines. The modern and most common variant of the airliner is a long, tube shaped, and jet powered aircraft. The largest of them are wide-body jets which are also called twin-aisle because they generally have two separate aisles running from the front to the back of the passenger cabin. These are usually used for long-haul flights between airline hubs and major cities. A smaller, more common class of airliners is the narrow-body or single-aisle. These are generally used for short to medium-distance flights with fewer passengers than their wide-body counterparts.
ValuJet Airlines Flight 592 was a regularly scheduled flight from Miami to Atlanta in the United States. On May 11, 1996, the ValuJet Airlines McDonnell Douglas DC-9 operating the route crashed into the Florida Everglades about ten minutes after departing Miami as a result of a fire in the cargo compartment probably caused by mislabeled and improperly stored hazardous cargo. All 110 people on board were killed.
Saudia Flight 163 was a scheduled Saudia passenger flight departing from Quaid-e-Azam Airport in Karachi, Pakistan, bound for Kandara Airport in Jeddah, Saudi Arabia, via Riyadh International Airport in Riyadh, Saudi Arabia, which caught fire after takeoff from Riyadh International Airport on 19 August 1980. Although the Lockheed L-1011-200 TriStar made a successful emergency landing at Riyadh, the flight crew failed to perform an emergency evacuation of the airplane, leading to the deaths of all 287 passengers and 14 crew on board the aircraft from smoke inhalation.
An uncontrolled decompression is an undesired drop in the pressure of a sealed system, such as a pressurised aircraft cabin or hyperbaric chamber, that typically results from human error, structural failure, or impact, causing the pressurised vessel to vent into its surroundings or fail to pressurize at all.
An oxygen mask is a mask that provides a method to transfer breathing oxygen gas from a storage tank to the lungs. Oxygen masks may cover only the nose and mouth or the entire face. They may be made of plastic, silicone, or rubber. In certain circumstances, oxygen may be delivered via a nasal cannula instead of a mask.
In aeronautics, an environmental control system (ECS) of an aircraft is an essential component which provides air supply, thermal control and cabin pressurization for the crew and passengers. Additional functions include the cooling of avionics, smoke detection, and fire suppression.
Cabin pressurization is a process in which conditioned air is pumped into the cabin of an aircraft or spacecraft in order to create a safe and comfortable environment for humans flying at high altitudes. For aircraft, this air is usually bled off from the gas turbine engines at the compressor stage, and for spacecraft, it is carried in high-pressure, often cryogenic, tanks. The air is cooled, humidified, and mixed with recirculated air by one or more environmental control systems before it is distributed to the cabin.
A flight suit is a full-body garment, worn while flying aircraft such as military airplanes, gliders and helicopters. These suits are generally made to keep the wearer warm, as well as being practical, and durable. Its appearance is usually similar to a jumpsuit. A military flight suit may also show rank insignia. It is sometimes used by Special Forces as a combat uniform in close quarters battle or visit, board, search, and seizure situations, for its practicality.
A chemical oxygen generator is a device that releases oxygen via a chemical reaction. The oxygen source is usually an inorganic superoxide, chlorate, or perchlorate. Ozonides are a promising group of oxygen sources, as well. The generators are usually ignited by a firing pin, and the chemical reaction is usually exothermic, making the generator a potential fire hazard. Potassium superoxide was used as an oxygen source on early crewed missions of the Soviet space program, in submarines for use in emergency situations, for firefighters, and for mine rescue.
The Learjet 25 is an American ten-seat, twin-engine, high-speed business jet aircraft manufactured by Learjet. It is a stretched version of the Learjet 24.
Helios Airways Flight 522 was a scheduled passenger flight from Larnaca, Cyprus, to Prague, Czech Republic, with a stopover in Athens, Greece. Shortly after take-off on 14 August 2005, Nicosia air traffic control (ATC) lost contact with the pilots operating the flight, named Olympia; it eventually crashed near Grammatiko, Greece, killing all 121 passengers and crew on board. It is the deadliest aviation accident in Greek history.
British Airways Flight 009, sometimes referred to by its callsign Speedbird 9 or as the Jakarta incident, was a scheduled British Airways flight from London Heathrow to Auckland, with stops in Bombay, Kuala Lumpur, Perth, and Melbourne.
On October 25, 1999, a chartered Learjet 35 business jet was scheduled to fly from Orlando, Florida, United States to Dallas, Texas, United States. Early in the flight, the aircraft, which was climbing to its assigned altitude on autopilot, lost cabin pressure, and all six on board were incapacitated by hypoxia, a lack of oxygen in the brain and body. The aircraft continued climbing past its assigned altitude, then failed to make the westward turn toward Dallas over North Florida and continued on its northwestern course, flying over the southern and midwestern United States for almost four hours and 1,500 miles (2,400 km). The plane ran out of fuel over South Dakota and crashed into a field near Aberdeen after an uncontrolled descent, killing all six on board.
An aircraft cabin is the section of an aircraft in which passengers travel. Most modern commercial aircraft are pressurized, as cruising altitudes are high enough such that the surrounding atmosphere is too thin for passengers and crew to breathe.
Qantas Flight 30, on 25 July 2008, a Boeing 747-438 operated by Qantas, construction number 25067, registration VH-OJK, was a scheduled flight from London Heathrow to Melbourne with a stopover in Hong Kong. The flight was interrupted on the Hong Kong leg by an exploding oxygen tank that ruptured the fuselage just forward of the starboard wing root. 53-year-old Captain John Bartels and his co-pilots, Bernd Werninghaus and Paul Tabac, made an emergency descent to a breathable altitude of about 10,000 feet (3,048 m) and diverted to Ninoy Aquino International Airport, Metro Manila, Philippines. There were no injuries.
Southwest Airlines Flight 2294 (WN2294/SWA2294) was a scheduled US passenger aircraft flight which suffered a rapid depressurization of the passenger cabin on July 13, 2009. The aircraft made an emergency landing at Yeager Airport in Charleston, West Virginia, with no fatalities or major injuries to passengers and crew. Investigation performed by the National Transportation Safety Board concluded that the accident was caused by a failure in the fuselage skin due to metal fatigue.
Aeroflot Flight 2306 was a scheduled domestic passenger flight from Vorkuta to Moscow in the Soviet Union, with a stopover in Syktyvkar. The Tupolev Tu-134 operated by Aeroflot crashed on 2 July 1986 during an emergency landing after it departed Syktyvkar, killing 54 of 92 passengers and crew on board.
On 29 July 2011, a Boeing 777 on a scheduled passenger flight from Cairo, Egypt, to Jeddah, Saudi Arabia, flying as Egyptair Flight 667, suffered a cockpit fire on the ground at Cairo Airport, while preparing to depart. There were no fatalities, but seven people were treated for smoke inhalation. The aircraft was damaged beyond economic repair.
Aeroflot Flight 558 was a scheduled Ilyushin Il-18V domestic passenger flight from Karaganda to Moscow that crashed into a field in the Abzelilovsky District on 31 August 1972 as a result of a fire stemming from exploded passenger baggage, killing all 102 people on board.
High altitude breathing apparatus is a breathing apparatus which allows a person to breathe more effectively at an altitude where the partial pressure of oxygen in the ambient atmospheric air is insufficient for the task or to sustain consciousness or human life over the long or short term.
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