In 1946 Normalair Ltd. was formed as a subsidiary company of Westland Aircraft Ltd. to meet the growing demands for this specialist equipment, and today employs 1,100 people and has its own extensive production facilities. Normalair operate the most extensive respiratory laboratory, and are the largest producers of aircraft pressurisation, air conditioning and oxygen breathing equipment, in Europe. All British military aircraft that are pressurised are fitted with Normalair equipment, and such famous airliners as the Viscount, Britannia and Comet are equipped by Normalair. With subsidiary companies in Canada and Australia, and with representatives and agencies all over the world, Normalair provides a very wide market with cabin pressure controllers, discharge valves, safety valves, humidifiers, water extractors, flow control valves, cooling turbines, oxygen regulators, liquid oxygen converters, and many items of equipment vital to the needs of the aircraft of today. For several years the company has had license agreements with the two American companies foremost in these fields, namely the Garratt Corporation of Los Angeles and Bendix Aviation of New York. These agreements have been the source of substantial dollar export business by Normalair. In 1953, Normalair provided the oxygen equipment that enabled Sir Edmund Hillary and Sherpa Tensing to be the first to conquer Everest and, in 1955, provided the oxygen sets that were used in the first successful assault on Mount Kanchenjunga. The company also produces lightweight portable oxygen equipment for medical, industrial and emergency use, and are the sales agents in the UK for the respirators and breathing equipment made by Mrs Dräger of Lubeck. This business is handled by Normalair's branch office in Manchester. The Garrett Corporation took a 48% share in the company in 1966, and was subsequently renamed Normalair-Garrett Limited (NGL). The company is now Honeywell Normalair Garrett Ltd.

John Clifford "Cliff" Garrett founded the company in Los Angeles in 1936. Garrett AiResearch was a manufacturer of turboprop engines and turbochargers, and a pioneer in numerous aerospace technologies. It was previously known as Aircraft Tool and Supply Company, Garrett Supply Company, AiResearch Manufacturing Company, or simply AiResearch. In 1964, Garrett AiResearch merged with Signal Oil & Gas to form a company renamed in 1968 to Signal Companies, which in 1985 merged with Allied Corp. into AlliedSignal. In 1999 AlliedSignal acquired Honeywell and adopted the Honeywell name. The Company's first major product was an oil cooler for military aircraft. Garrett designed and produced oil coolers for the Douglas DB-7.[3] Boeing's B-17 bombers, credited with substantially tipping the air war in America's and Great Britain's favor over Europe and the Pacific, were outfitted with Garrett intercoolers, as was the B-25. The Company developed and produced the cabin pressure system for the B-29 bomber, the first production bomber pressurized for high altitude flying. By the end of World War II, AiResearch engineers had developed air expansion cooling turbines for America's first jet aircraft, the Lockheed P-80 Shooting Star. In the late 1940s and early 1950s, Garrett was heavily committed to the design of small gas turbine engines from 20 - 90 horse power (15 - 67 kW). During the 1950s AiResearch initiated activities in the field of aircraft electronics, and designed and produced a wide range of military and industrial products for aerospace and general industry. It focused on fluid controls and hydraulics, avionics, turbochargers, aircraft engines, and environmental control systems for aircraft and spacecraft. By 1960 Garrett gas turbines, cabin pressurization systems, air conditioners, and flight control systems were aboard the Convair 880, Lockheed Super Constellation, Vickers Viscount, Sud Aviation Caravelle, Douglas DC-8, and Boeing 707. The company had also developed the first inflatable airliner evacuation slides. In the 1950s and 1960s Garrett pioneered the development of foil bearings, which were first installed as original equipment on the McDonnell-Douglas DC-10 in 1969 and then became standard equipment on all U.S. military aircraft. In the 1960s, AiResearch Environmental Control Systems provided the life supporting atmosphere for American astronauts in the projects Mercury, Gemini, Apollo, and Skylab. By 1962, Garrett was powering the world’s first turbocharged production car, the Oldsmobile Jetfire Rocket. This was followed by several other firsts, including the first turbocharged car to win the Indianapolis 500 (1968), the first turbo for a non sports car application (1977-Saab 99), the first mass production turbo for diesel engines (1978-Mercedes 300SD), and the first turbo to win the 24 Hours of Le Mans (1978-Renault).

The Bendix Aviation Corporation was a manufacturer of aircraft parts based from 1929 to 1960 in Los Angeles, California. It was started by inventor Vincent Bendix in 1929 as a continuation of his auto parts company. It was renamed to Bendix Corporation in 1960, and in 1983 was acquired by the Allied Corporation (later Allied Signal) and combined with King Radio Company to form Bendix/King. Now owned by Honeywell, Bendix/King remains a brand of avionics. Bendix Aviation developed and manufactured advanced carburetion for aircraft engines; landing gear oleo struts; jet engine fuel controls for early J79 engines; and designed guidance systems and assembled the Talos missile for the US Navy. Bendix aviation masks and gauges were also modified and tested for use in diving and hyperbaric applications.