What is a key limitation of using EMER mode for flight spoilers?

The key limitation of using EMER mode for flight spoilers is that it is intended for use only during emergencies. This mode is specifically designed to provide enhanced control and safe deceleration in critical situations, usually when standard operational modes are not sufficient. EMER mode activates the flight spoilers regardless of the flap or gear positions to ensure maximum aerodynamic drag and reduce the aircraft's speed quickly.

In contrast, the other options refer to scenarios where the use of flight spoilers is either unrestricted or tied to specific operational phases, like normal operations or takeoff. Therefore, these do not align with the designed purpose of EMER mode, which is strictly reserved for emergencies to ensure safety and effective handling of urgent situations.