If you travel often by flights you must’ve observed that the pre-flight cabin is either too hot or too cold. While the reason behind this goes unquestioned by many, we have an answer for that.
When on the ground the aircraft has only a single engine running which is the APU (Axillary Power Unit). The APU is responsible for providing power to the display units during the pre-flight stage, and also controls the air-conditioning system. While the use of APU is important, many airports and companies have strict rules regarding its use. They allow it to be switched on for only a certain time period. This is done to prevent noise and high fuel consumption.
Since the APU remains switched off, the temperature inside the aircraft becomes uncontrollable. This simply means that the temperature is at the mercy of where the flight lands or takes off. A cold place of departure will result in the cabin being cool while a hotter place will naturally make the cabin hot, until the APU is turned on and the air conditioning kicks in.
Although a cold cabin when in the air may be a result of pilots feeling hot due to direct sunlight in the cockpit, or perhaps the flight attendants feeling hot due to their continuous movement in the cabin.
So the next time you are on an airplane, you know why the temperature is the way it is.
Over and Out!