How does the system determine which bleed source to utilize for optimal performance?

The system determines which bleed source to utilize for optimal performance automatically based on temperatures. This automatic selection process is performed by the aircraft's environmental control system, which continuously evaluates various parameters including engine and ambient temperatures. The goal is to ensure that the aircraft maintains comfortable cabin conditions while optimizing engine performance and efficiency.

By monitoring the temperatures, the system can effectively select the most appropriate bleed air source, whether from the engines or APU (Auxiliary Power Unit), to maintain the desired air pressure and temperature in the cabin without compromising engine performance. This automatic adjustment helps in achieving a balance between cabin environmental needs and overall aircraft efficiency.