Final answer:
A pilot can request a special VFR clearance to operate in a control zone when the weather is below VFR minimums, requiring at least one statute mile flight visibility and the ability to remain clear of clouds.
Step-by-step explanation:
A pilot may request and receive a special VFR clearance when he or she wishes to enter or operate within a control zone under meteorological conditions that are less than the minima required for visual flight rules (VFR) flights. This type of clearance allows pilots to continue flying in VFR conditions despite weather that might normally require them to fly under instrument flight rules. However, a special VFR clearance is subject to certain conditions; for instance, in the United States, it can only be granted if the flight visibility is at least one statute mile and the pilot can remain clear of clouds while maintaining visual reference with the ground. Additionally, between sunset to sunrise, or during the night in some regions, the pilot must be qualified and the aircraft must be equipped for instrument flight.