What is the maximum altitude for using slats and flaps?

The maximum altitude for using slats and flaps on the CRJ 900 is specifically prohibited above 15,000 ft. This limitation is primarily in place to ensure safe flight operations, as the aerodynamic characteristics of the aircraft change at higher altitudes. The use of lift augmenting devices like slats and flaps is designed for lower altitude operations during takeoff and landing phases, where they significantly improve lift and control at slower speeds.

Operating with slats and flaps at altitudes above this limit can lead to reduced performance and handling issues, which could compromise safety. Thus, adhering to this altitude limit is crucial for maintaining optimal aircraft performance and ensuring safe operation.