What is the maximum altitude for APU generator use?

The maximum altitude for APU (Auxiliary Power Unit) generator use is set at 30,000 feet AGL (Above Ground Level). This altitude limitation is primarily based on the operational efficiency and reliability of the APU, as well as the need for consistent electrical output under varied atmospheric conditions. At altitudes higher than this threshold, the APU may struggle to function effectively due to reduced air density, which can affect its performance and ability to generate adequate power.

In aviation operations, it is crucial to adhere to these altitude limitations to ensure the safety and functionality of the aircraft's systems. Understanding this aspect of APU utilization helps pilots and crew maintain operational integrity, particularly during high-altitude flights.