What is the purpose of an air conditioning unit on the ground?

The air conditioning unit on the ground is crucial for maintaining a comfortable and safe environment within the aircraft before departure and after arrival. It supplies conditioned air to the aircraft’s cabin and cockpit, ensuring the temperatures are controlled, and the humidity levels are appropriate. This is especially important as aircraft can heat up quickly when sitting on the tarmac under direct sunlight, making the cabin uncomfortable for passengers and crew.

Additionally, preconditioning the air before boarding can help to reduce the total time needed for air conditioning during the flight, contributing to overall operational efficiency when the engines are running. By providing a comfortable atmosphere on the ground, it also enhances passenger safety and comfort during boarding and waiting times.