Airbus A320 family

The Airbus A320 family consists of short- to medium-range, narrow-body, commercial passenger twin-engine jet airliners manufactured by Airbus. The family includes the A318, A319, A320 and A321, as well as the ACJ business jet. The A320s are also named A320ceo (current engine option) after the introduction of the A320neo. Final assembly of the family takes place in Toulouse, France, and Hamburg, Germany; a plant in Tianjin, China, has also been producing aircraft for Chinese airlines since 2009. Construction of a new production facility in Mobile, Alabama began in 2013. The aircraft family can accommodate up to 220 passengers and has a range of 3,100 to 12,000 km (1,700 to 6,500 nmi), depending on model.

The first member of the A320 family—the A320—was launched in March 1984, first flew on 22 February 1987, and was first delivered in March 1988. The family was soon extended to include the A321 (first delivered 1994), the A319 (1996), and the A318 (2003). The A320 family pioneered the use of digital fly-by-wire flight control systems, as well as side-stick controls, in commercial aircraft. There has been a continuous improvement process since introduction.

American Airlines

American Airlines, Inc. (AA) is a major American airline headquartered in Fort Worth, Texas. Operating an extensive international and domestic network, American Airlines is the world's largest airline by fleet size and revenue, and the second largest by number of destinations served, after United Airlines. It operates from its main hub at Dallas/Fort Worth, and its hubs at Charlotte, Chicago-O'Hare, Los Angeles, Miami, New York-JFK, New York-LaGuardia, Philadelphia, Phoenix, and Washington, D.C., while its primary maintenance base is at Tulsa International Airport. Its primary competitors are United Airlines, Delta Air Lines, and Southwest Airlines.

American Airlines is a founding member of the Oneworld airline alliance, and coordinates fares, services, and scheduling with British Airways, Iberia, and Finnair in the transatlantic market and with Japan Airlines in the transpacific market. Regional service is operated by independent and subsidiary carriers under the brand name American Eagle.

British Airways

British Airways, often shortened to BA, is the flag carrier airline of the United Kingdom and the largest airline in the United Kingdom based on fleet size. When measured by passengers carried, it is second-largest in United Kingdom (behind easyJet). The airline is based in Waterside near its main hub at London Heathrow Airport.

A British Airways Board was established by the United Kingdom government in 1972 to manage the two nationalized airline corporations, British Overseas Airways Corporation and British European Airways, and two smaller, regional airlines, Cambrian Airways, from Cardiff, and Northeast Airlines, from Newcastle upon Tyne. On 31 March 1974, all four companies were merged to form British Airways. After almost 13 years as a state company, British Airways was privatised in February 1987 as part of a wider privatisation plan by the Conservative government. The carrier soon expanded with the acquisition of British Caledonian in 1987, followed by Dan-Air in 1992 and British Midland International in 2012.

Altitude

Altitude or height (sometimes known as depth) is defined based on the context in which it is used (aviation, geometry, geographical survey, sport, and many more). As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context. Although the term altitude is commonly used to mean the height above sea level of a location, in geography the term elevation is often preferred for this usage.

Vertical distance measurements in the "down" direction are commonly referred to as depth.

Altitude in aviation

In aviation, the term altitude can have several meanings, and is always qualified by either explicitly adding a modifier (e.g. "true altitude"), or implicitly through the context of the communication. Parties exchanging altitude information must be clear which definition is being used.

Aviation altitude is measured using either mean sea level (MSL) or local ground level (above ground level, or AGL) as the reference datum.

Weather balloon

A weather or sounding balloon is a balloon (specifically a type of high altitude balloon) which carries instruments aloft to send back information on atmospheric pressure, temperature, humidity and wind speed by means of a small, expendable measuring device called a radiosonde. To obtain wind data, they can be tracked by radar, radio direction finding, or navigation systems (such as the satellite-based Global Positioning System, GPS). Balloons meant to stay at a constant altitude for long periods of time are known as transosondes.

History

One of the first people to use weather balloons was Léon Teisserenc de Bort, the French meteorologist. Starting in 1896 he launched hundreds of weather balloons from his observatory in Trappes, France. These experiments lead to his discovery of the tropopause and stratosphere. Transosondes, weather balloons with instrumentation meant to stay at a constant altitude for long periods of time to help diagnose radioactive debris from atomic fallout, were experimented with in 1958.