How long is the maximum operation altitude for electrical systems with the APU?

The maximum operational altitude for electrical systems powered by the Auxiliary Power Unit (APU) on the ERJ 170/175 is 33,000 feet. At this altitude, pilots can use the APU to provide electrical power and air conditioning while adhering to safety and operational guidelines. This limitation is important as it affects the planning of flights, particularly in terms of system redundancy and power availability during various phases of flight.

The specifications regarding the altitude help ensure that the aircraft's electrical systems remain functional under conditions that may affect performance and safety. Understanding this limitation is essential for making informed decisions during flight operations, including when to rely on the APU for auxiliary power.