Simplified directional facility
Simplified Directional Facility or SDF is similar to a Localizer, although is not as precise. The SDF signal is fixed at either 6 or 12 degrees, as necessary maximum flyability and optimum course quality.
The SDF course may or may not be aligned with the runway because its antenna is sometimes offset from the runway centerline.
Usable off-course indications are limited to 35 degrees either side of the course centerline.
List of Current SDF Approaches in the United States
The following 14 SDF approaches in five states are currently published in the United States (currently only 11 are available):
- KDWU SDF RWY 10, Ashland Regional Airport, Ashland, KY
- KAAS SDF RWY 23, Taylor County Airport, Campbellsville, KY (SDF unmonitored 1700-0800)
- KGLW SDF RWY 07, Glasgow Municipal Airport, Glasgow, KY (SDF unmonitored 1600-0700)
- KAMN SDF RWY 09, Gratiot Community Airport, Alma, MI
- KLBO SDF RWY 36, Floyd W. Jones Lebanon Airport, Lebanon, MO (Course width: 6.00 degrees, SDF/DME unmonitored)
- KPOF SDF RWY 36, Poplar Bluff Municipal Airport, Poplar Bluff, MO (Course width: 6.00 degrees)
- KMRC SDF RWY 24, Maury County Airport, Columbia/Mount Pleasant, TN (Course width: 6.00 degrees, currently out of service)
- KFYM SDF RWY 20, Fayetteville Municipal Airport. Fayetteville, TN (Course width: 6.00 degrees, SDF unmonitored 1700-0800)
- KMOR SDF RWY 05, Moore-Murrell Airport, Morristown, TN (SDF unmonitored 2100-0700)
- KSCX SDF RWY 23, Scott Municipal Airport, Oneida, TN (SDF unmonitored 1730-0830, currently out of service)
- KTHA SDF RWY 18, Tullahoma Regional Airport/William Northern Field. Tullahoma, TN (Course width: 6.00 degrees, SDF unmonitored 1800-0800 and at other times the airport is unattended, currently out of service)
- KMFI SDF RWY 34, Marshfield Municipal Airport, Marshfield, WI
- KSUE SDF RWY 02, Door County Cherryland Airport, Sturgeon Bay, WI (SDF unmonitored and unusable beyond 12 degrees right of course)
- KISW SDF RWY 02, Alexander Field South Wood County Airport, Wisconsin Rapids, WI, (Course width: 6.36 degrees, SDF unmonitored)