When does ATC take responsibility for separation between aircraft in an ALTRV?

In the context of an Area of Limited Military Operations (ALTRV), ATC (Air Traffic Control) assumes responsibility for maintaining separation between aircraft primarily when MARSA (Military Assistance to Ramp System Authority) does not apply. MARSA is a concept that applies during military operations where military aircraft have autonomy in their operations and separation responsibilities may not fall solely on ATC.

When MARSA does not apply, ATC steps in to manage the separation between all aircraft within the ALTRV airspace, ensuring safety and compliance with aviation regulations. This is crucial because, in environments where multiple aircraft operate, clear separation protocols must be established to prevent potential conflicts, especially when integrating military operations into civilian airspace.

The other choices do not directly relate to the condition under which ATC assumes separation responsibility. For instance, poor weather conditions may make separation more challenging but do not change the fundamental responsibility timeline. Similarly, altitude thresholds or active military operations are operational considerations but do not dictate when ATC takes over separation duties. The focus remains on the presence or absence of MARSA to determine procedural responsibilities for separation.