What are air management systems in airplanes and how do they work?

Planes are the fastest, most comfortable travel choice available, and, no doubt about it, an exciting way to reach your destination. While a two-hour plane ride can be a pleasant experience, longer flights usually translate into backpain, fatigue, swollen hands and feet, and an urge to get back on safe land and stretch all your muscles. What gets both passengers and cabin crew through the challenges of long, exhausting flights are air management systems.

What are air management systems?

Air management systems monitor and control cabin temperature, creating a comfortable flying experience for passengers and crew members. They are integral to an environmental control system (ECS), which ensures the air supply, optimal cabin pressurization and thermal management of the aircraft. However, there is more to the ECS – smoke detection, fire suppression as well as avionics components cooling process are all managed by this vital air and temperature system.

Let’s take a quick look over the main capabilities of air management systems and how they benefit you on every flight you take.

Air conditioning

The air conditioning system on planes works on air supplied through air cycle packs, situated on each side of the fuselage, next to the main landing gear, that manage both airflow and air temperature. In order to deliver air at an ideal temperature, the air management system combines hot and cold air, controls the airflow and recirculates the cabin air for proper ventilation.

Packs are essential to any aircraft environmental control system and are responsible for airflow, temperature and pressurization management, among others. Although the name does not suggest it, packs are complex pieces of equipment, comprising heat exchangers (primary and secondary), an air cycle machine, a condenser, a water extractor, a re-heater and other important parts.   

Now, back to air supply. Have you ever wondered how fresh air is pulled inside the air management system, before getting filtered and conditioned? Air supply is no easy task, although virtually planes sail through air.

The air that reaches the cabin is called bleed air and it is supplied to the air management system through the aircraft’s pneumatic system. The cycle goes like this: bleed air is delivered to the pneumatic system via engine compressors or an APU pneumatic supply, which is then directed into the primary heat exchanger of the air cycle packs, and then injected into the cabin.

In what concerns the air distribution system inside the aircraft, this operates on ground conditioned air and a smart recirculation system. The air is pulled in, mixed for optimal temperature and distributed based on an airplane compartment strategy. What this means is that different air sources vent the flight compartment and passenger compartment. Mainly, the flight compartment gets air delivered from one of the air cycle packs and the air mixing distributor, while the passenger compartment receives air straight from the latter.

Distribution is done through air ducts located within the aircraft walls. Air is recirculated through a two-fan system, that guides the air to and from the passenger compartment and mix manifold, in a controlled, repeated process. Air recirculation is important because it cuts down the total amount of air needed for the air cycle packs and can repurpose up to 50% of the cabin air for ventilation and auxiliary usage.

Inevitably, repurposed, recycled air brings to mind an important question: can the air recirculation system negatively impact your health? The answer is no. Today’s aircraft are equipped with high-standard air filters, much like the ones used in medical operating rooms. Air quality checks are frequently performed on all flying aircraft, in order to ensure the air filters and air conditioning systems are compliant to safety and hygiene standards.

Temperature control

Another important application of air management systems consists in air temperature control. This is an essential aspect for aircraft and avionics manufacturing companies because it is a make-or-break condition for the safety, livability and comfort of an aircraft.

By general standards, the cabin temperature needs to be maintained at 68°F (20°C). If the ambient air temperature drops or rises, below or above this benchmark, the cabin crew needs to take action, as it can affect passenger comfort. Nevertheless, temperature control is a challenging task, given that flight conditions almost never allow for outside temperature as high as 68°F.

Typically, the temperature control system employs overheat switches situated in the air supply ducts, that can signal when the temperature has passed normal limits. 

Temperature information is then sent out to the cabin temperature control panel, that displays the current, exact air temperature. The temperature controller device can then compare the actual temperature signals received from the sensors to the desired temperature input. If the temperature is too low, air from the pneumatic system is supplemented to the cooler area of the aircraft, but not before it is mixed with cold air, in order to reach a comfortable temperature.

In order to increase the temperature level, pilots use the air management system for temperature control, where hot air is tapped from the engine compressor, mixed in the manifold to reach the optimal ambient temperature, and then delivered inside the cabin.

For cooling down the air, which is rarely a problem when you’re in flight, but can often happen on the ground, compressed air is, once again, the solution. The air management system has the capability to cool down compressed air by expanding it, but only with the help of a designated auxiliary power unit. 

Honeywell Aerospace is a leading air management systems manufacturer and provider, with consistent research and development activity in aircraft environmental control, in order to deliver best-in-class products. Honeywell’s air management systems portfolio includes air conditioning and temperature control systems, air distribution equipment and systems, as well as bleed air and anti-ice technology.