How Does Air Con Work Within Airplanes?

Air conditioning systems help to make the environment we are in more comfortable. Airplanes too are fitted with these systems. In this article, we will be explaining how air conditioners and Charge air cooler in airplanes work. Let's get started.

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In airplanes, the air conditioning systems utilizes air from the pneumatic system to supply warmth or cold to the cock picture and passenger compartment. The engines supply air during flight to the air conditioner. But when the plane is on the ground, it is an external high-pressure (HP) air source or the auxiliary power unit (APU) may be used to supply air to the AC. Optionally, a low-pressure air conditioning connection may be available. This connection can be used to supply conditioned air to the flight and cabin compartments directly, instead of the APU bleed or engine air sources.


A cabin pressure controler is used to control automatically the pressurisation of the cabin. This device also has a provision for manual backup control. This system is fitted with safety valves that are used to prevent a build up of positive or negative pressures in the compartments. The following subsystems are part of an airplane'a air conditioning system:

- Temperature control

- Cooling

- Pressurisation control

- Distribution

The following components provide indication and control of the air conditioning system:

- A control panel which is located in the overhead panel for cabin pressurisation

- EICAS ECS synoptic page

- A flight attendant panel which is located in the forward galley

- An avionics cooling panel which is located in the center pedestal

- Air conditioning panel located in the overhead panel

The data for pressurization and system messages are displayed on the EICAS Status Page and the EICAS Primary and Status pages respectively.


Conditioned air is directed by the air distribution system from the air conditioner to the passenger compartment and the cock pit. To ensure that the air flow in the passenger compartment is not disrupted, a recirculating system is used. Also, the plane has ventilation systems to remove air from the afternoon cargo, lavatories, and gallery areas. Avionics and cock pit displays are cooled by electric fans. Supplementary heating for the door and gallery areas is provided by an electric gallery heater.


Air to the cock pit and the passenger compartment is cleaned and supplied by the cooling system. The plane also has two more air conditioning units that are used to decrease the temperature and remove water from the air from the pneumatic system. When it comes to cooling the air conditioner and in some cases to supply emergency air to the distribution system in case the air conditioners are not working, ram air is used. The pressure and temperature of the air being distributed is monitored by the cooling system. Ventilation to the afternoon cargo compartment is provided by the cargo compartment air conditioner.

The air conditioning and pressurisation systems of an airplane are complex. They include many components and subsystems. We have tried our best to explain how it works as much as we could. We hope that this article has been of value to you.