Folk v. Sturgell, 375 Fed. Appx. 308 (4th Cir. 2010)

(farmers violated FAA regulations by flying crop-dusting planes too low over an intersection in a congested area; regulations not unconstitutionally vague for failing to define "congested area" - FAA inspector had warned that "two or three houses may be considered a congested area", thus farmers on notice that area where they were flying could be determined to be a congested area).