Even before the current pandemic situation, aircraft cabin air quality was becoming a hot topic of discussion. There have been studies conducted hypothesizing that the aircraft onboard Environmental Control System (ECS) provides satisfactory passenger safety regarding certain airborne contaminants. As such, many airlines have been using the ECS during passenger boarding and deplaning. This onboard system utilizes 50% outside air combined with 50% recirculated air from within the aircraft cabin as an air conditioning medium. The term air conditioning refers to heating, ventilation and cooling. The 50% recirculated air is passed through HEPA grade filters. The total cabin air content can be exchanged as often as 20 times per hr.
In order to use the ECS on the ground, an Auxiliary Power Unit (APU) must be running to supply the power and air delivery sources. An auxiliary power unit is a smaller jet engine, for running certain systems when the main engines are turned off. With outdoor environmental concerns, related to fossil fuel combustion, and rising jet fuel prices, this will be an unsustainable business model to maintain, in my opinion.
My position is that a proper Pre Conditioned Air (PCA) machine, with highly efficient filtration and superior air flow capability, can be an alternative to running an APU on the ground. It is my intention, in this composition, to explain some of my opinions regarding how PCA units can provide excellent ventilation for an aircraft cabin when modern technology is applied. Advanced PCA filtering and airflow proficiencies will be necessary due to the growing desire for better indoor and outdoor air quality conditions. Though not necessarily the topic of this composition, end user mindfulness of hose configurations will also remain essential for air flow quantity which matches the onboard ECS.