Let's say I'm on an SVFR clearance and the flight and reported ground visibility deteriorates less than 1 mile, what happens?
If the pilot is on an SVFR clearance, the weather inside the surface area deteriorates below 1 mile visibility, and the pilot has the airport in sight, he can inform the controller that he has the field in sight and will be cleared to land. The pilot is responsible for continuing to the airport or exiting the surface area in order to remain visual.
NOTE− Clear an aircraft to land at an airport with an operating control tower, traffic permitting, if the pilot reports the airport in sight. The pilot is responsible to continue to the airport or exit the surface area. 14 CFR Section 91.157 prohibits VFR aircraft (other than helicopters) from landing at any airport within a surface area when flight visibility is less than 1 mile. A pilot could inadvertently encounter conditions that are below SVFR minimums after entering a surface area due to rapidly changing weather. The pilot is best suited to determine the action to be taken since pilots operating under SVFR between sunrise and sunset are not required to be instrument rated, and the possibility exists that flight visibility may not be the same as ground visibility. 14 CFR Section 91.3 authorizes a pilot encountering an inflight emergency requiring immediate action to deviate from any rule of 14 CFR Part 91 to the extent required to meet that emergency. Flight into adverse weather conditions may require the pilot to execute the emergency authority granted in 14 CFR Section 91.3 and continue inbound to land. Air Traffic Control Handbook, 7−5−4