Which of the following is NOT a limitation regarding the use of flight spoilers?

The correct choice highlights an important aspect of flight spoilers: they can indeed be extended in flight at any speed, which is not a limitation but rather a standard operational condition for many aircraft. This means that pilots can utilize spoilers within the aircraft's operational envelope during flight, contrary to the other options that specify limitations.

The first choice points out a specific operational limitation regarding the extension of flight spoilers below a certain approach speed, emphasizing the need for adherence to safe operational parameters during the approach phase.

The second choice addresses the use of emergency settings, indicating that spoilers should be used with caution and primarily in emergencies. This highlights prudent operational practices that prevent misuse of the system outside of critical situations.

The last choice specifies a limitation concerning the extension of spoilers below a certain altitude, reflecting additional safety parameters that pilots must follow to ensure safe flight operations.

In summary, the identification of unrestricted use of spoilers in flight underlines their flexibility as a control mechanism, which is an essential understanding for effective aircraft operation.