FAA Federal Aviation Regulations (FARS, 14 CFR)

(a) Each pilot compartment must be free from glare and reflections that could interfere with the pilot's view, and designed so that --

(1) Each pilot's view is sufficiently extensive, clear, and undistorted for safe operation; and

(2) Each pilot is protected from the elements so that moderate rain conditions do not unduly impair his view of the flight path in normal flight and while landing.

(b) If certification for night operation is requested, compliance with paragraph (a) of this section must be shown in night flight tests.