§23.1387 Position light system dihedral angles.

[(a) Except as provided in paragraph (e) of this section, each position light must, as installed, show unbroken light within the dihedral angles described in this section.] (b) Dihedral angle L (left) is formed by two intersecting vertical planes, the first parallel to the longitudinal axis of the airplane, and the other at 110� to the left of the first, as viewed when looking forward along the longitudinal axis. (c) Dihedral angle R (right) is formed by two intersecting vertical planes, the first parallel to the longitudinal axis of the airplane, and the other at 110� to the right of the first, as viewed when looking forward along the longitudinal axis. (d) Dihedral angle A (aft) is formed by two intersecting vertical planes making angles of 70� to the right and to the left, respectively, to a vertical plane passing through the longitudinal axis, as viewed when looking aft along the longitudinal axis. (e) If the rear position light, when mounted as far aft as practicable in accordance with Sec. 23.1385(c), cannot show unbroken light within dihedral angle A (as defined in paragraph (d) of this section), a solid angle or angles of obstructed visibility totaling not more than 0.04 steradians is allowable within that dihedral angle, if such solid angle is within a cone whose apex is at the rear position light and whose elements make an angle of 30� with a vertical line passing through the rear position light.