What is the maximum altitude for starting the APU?

The maximum altitude for starting the APU (Auxiliary Power Unit) in a CRJ 200 is indeed 30,000 feet. This limitation is important because the APU has performance parameters that dictate its operational capabilities at various altitudes. At altitudes above this threshold, the APU may not function effectively or provide the necessary power due to decreased atmospheric pressure and reduced air density.

This altitude limit is set to ensure reliable operation of the APU, which is used for generating electrical power and providing air conditioning prior to takeoff or after landing when the main engines are not operational. Understanding these limitations is critical for safe and efficient aircraft operation, as exceeding these limits could lead to insufficient APU performance or potential inoperative conditions when needed.