Section 221.15 - Marking device inspection(a) Each marking device displayed in compliance with this part shall be examined at each crew change point to assure that the device is in proper operating condition.(b) This examination shall be accomplished either by visually observing that the device is functioning as required or that the device will function when required by either:(1) Repositioning the activation switch or(2) Covering the photoelectric cell.(c) This examination shall be conducted either by the train crew or some other qualified person, Provided that, if a non-train crewmember performs the examination, that person shall communicate his or her findings to the locomotive engineer of the new train crew.(d) When equipped with a radio telemetry capability, a marker displayed in accordance with this part may be examined by observing the readout information displayed in the cab of the controlling locomotive demonstrating that the light is functioning as required in lieu of conducting a visual observation.51 FR 25185, July 10, 1986