How to Choose the Best Airplane Pre-Conditioning Air Unit | DREZAIRCON Guide Airplane pre-conditioning air units (PCA units) play a vital role in maintaining the comfort and safety of passengers and crew while the aircraft is parked on the ground. These systems supply cooled or heated air to the aircraft cabin and cockpit, keeping temperature and humidity at optimal levels without running the main engines or auxiliary power units. Choosing the right PCA unit is crucial...