47 C.F.R. § 95.3303
Definitions, the 76-81 GHz Band Radar Service
(a) Air operations area. See § 87.5 of this chapter.
(b) Field disturbance sensor. See § 15.5(l) of this chapter.
(c) Foreign object debris (FOD) detection radar. A radar device designed to detect foreign object debris in airport air operations areas and to monitor aircraft as well as service vehicles on taxiways, and other airport vehicle service areas that have no public vehicle access.
(d) Radar. See § 2.1(c) of this chapter.