(a) The purpose of this subpart is to prevent accidents and casualties that can result from the operation of trains when safety devices intended to improve the safety of their movement have been disabled.

(b) This subpart does not prohibit intervention with safety devices that is permitted:

(1) Under the provisions of § 236.566 or § 236.567 of this chapter;

(2) Under the provisions of § 218.61 of this part; or

(3) Under the provisions of § 229.9 of this chapter, provided that when a locomotive is being operated under the provision of § 229.9(b) a designated officer has been notified of the defective alerter or deadman pedal at the first available point of communication.