Air Conditioning and Pressurization Systems in Modern Aircraft


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What happens when the air conditioning/pressurization fails at such high altitudes? Photo Credit: Ron

Failure of the Air Conditioning Packs

Although the A/C packs on the A 320 Airbus operate independently, the aircraft still prepares for any abnormality resulting in the failure of both of the A/C packs. A ram air inlet ducts ram air to the mixing unit directly, the flow of which is regulated via a ram air valve. However, ram air can only be used at a level below 10,000ft.

An ECAM (Electronic Centralized Aircraft Monitor) constantly measures the following parameters of the  conditioning system: pack flow, compressor outlet temperature, by-pass valve position, and pack outlet temperature.

Pressurization is achieved via the air pressurization system. Treated air is introduced into the aircraft, and its pressure is increased to create a comfortable environment within the aircraft. Through this process, the maintained partial pressure of oxygen is greater inside the aircraft, in comparison to the partial pressure of oxygen that exists outside.

A/C and Pressurization Systems: Critical in High-Altitude Aircraft

Air conditioning and pressurization systems are vital to human life at such high altitudes. Any event that involves explosive depressurization during flight can prove to be fatal, and in fact has been fatal as is clear from the history of commercial aviation.


Boeing. Cabin Air Systems. Accessed February 21, 2012.

NASA Glenn Research Center. Air Density. Accessed February 21, 2012.

Oxford Aviation Services. Human Performance and Limitations. Joint Aviation Authorities Airline Transport Pilot’s License Theoretical Knowledge Manual. (2001). Accessed February 21, 2012.

Joint Aviation Authority. Publications and NPAs. (2012). Accessed February 22, 2012.

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