Flying a C172 toward Columbia, MO, one day, I grew nervous as the ATIS spoke of lower and lower visibilities. Columbia Regional Airport sits atop the bluffs of the Missouri River, not far from the banks, and is prone to fog when a light wind blows up from the southeast, as it was that morning. The ATIS recording called the sector visibility to the southeast to be three miles, then one, then one-half, and then the entire field went IFR in all quadrants, according to the Tower reports.
Approaching from the west, I could see a thin film of fog over the river itself, then a clear patch of earth beyond, and lastly, fog … where the airport should be. But wait! I could see almost all of one runway, clear as a bell—the runway was clear, it was just the tower, on the southeast side of the airport, which was enveloped in fog. It was wide-open VFR to a landing, but technically the airport was IMC.
So, how could I legally land?
Federal Air Regulations require a flight visibility of three miles, and cloud clearance of 500 feet below, 1000 feet above, and 2000 feet horizontally for VFR flight in controlled airspace radiating from the surface of an airport upward — basically, in Class D airspace. FAR 91.157 (Special VFR weather minimums) lets us “violate” this requirement if the flight visibility near an airport is at least one mile, and we can remain clear of the clouds — which is a lot like what I saw at KCOU that day. There are some limits on Special VFR, however:
Special VFR (SVFR) is:
- An ATC clearance — you have to ask for, and be granted, permission to fly SVFR.
- Available only between sunrise and sunset unless:
- the pilot requesting SVFR is instrument rated and current, and is flying an airplane equipped and currently legal for instrument flight, or
- the aircraft is a helicopter, or
- in Alaska, when the sun is 6 degrees below the horizon or higher.
Complications: SVFR will likely be denied if there’s an airplane inbound for an instrument approach, or if an IFR airplane is ready for departure. Also, many large airports do not permit SVFR at any time. Finally, SVFR is available only up to 10,000 feet MSL. In most cases, Special VFR is for daytime use only — whether you and your airplane are instrument rated or not.
When You’d Use It…
If you’re trying to get into or out of a controlled airport, and the reported visibility is less than three miles and/or the ceiling is less than 1000 feet (allowing you 500 feet clearance both from the ground and from the base of the clouds), you can ask for Special VFR.
How You’d Use It…
Ask for it by name –“Columbia Tower, request Special VFR Clearance for landing at Columbia.” You’ll likely get a reply of “N12345 maintain one mile visibility and clear of clouds, special VFR is granted.” Again, if an IFR airplane is or is about to use the airspace, you might be told instead, “N12345, maintain VFR, special VFR is denied.”
Planning to use Special VFR is taking a chance that it might not be granted — or that you might encounter weather you’re not prepared for. Always have a backup plan, whether it be flying in “standard” VFR to somewhere else, or obtaining an instrument clearance if the option’s available to you. Evaluate the risk of flying SVFR, know your limits and don’t expect the weather to respect either precaution. Special VFR is one way to “use” the system or to get yourself out of a jam near and into an airport. Just make sure it doesn’t work the other way around…