Speed brake extension is inhibited when?

When the airplane is in the full flaps configuration, the extension of the speed brakes is inhibited to ensure aircraft stability and safety during landing and approach phases. Full flaps are typically used at lower speeds to increase lift and drag, which are crucial when the aircraft is in landing configuration. Allowing speed brakes to extend in this setting could lead to undesirable aerodynamic effects, such as increased drag and potential changes in airflow, which might destabilize the aircraft during critical phases of flight.

In contrast, under high-speed conditions, certain protections may indeed restrict speed brake use, but that is not directly related to the flap configuration. Similarly, while configurations with flaps at position 3 may have certain operational parameters, they do not impose the same restriction as the full-flaps setting. Lastly, being in alternate law does influence the aircraft's flight envelope and protections, but it doesn't specifically inhibit speed brake extension related to flap configuration.