(a) When any safety-critical PTC system component fails to perform its intended function, the cause must be determined and the faulty component adjusted, repaired, or replaced without undue delay. Until repair of such essential components is completed, the railroad shall take appropriate action as specified in its PTCSP.

(b) Where a trainset that is operating in, or is to be operated within, a PTC-equipped track segment experiences a PTC system failure or the PTC system is otherwise cut out while en route (i.e., after the trainset has departed its initial terminal), the trainset may only continue in accordance with all of the following:

(1) Except as provided in paragraph (b)(4) of this section, when no absolute block protection is established, the trainset may proceed at a speed not to exceed restricted speed.

(2) When absolute block protection can be established in advance of the trainset, the trainset may proceed at a speed not to exceed 120 km/h (75 mph), and the trainset shall not exceed restricted speed until the absolute block in advance of the trainset is established.

(3) A report of the failure or cut-out must be made to a designated railroad officer of the railroad as soon as safe and practicable.

(4) Where the PTC system is the exclusive method of delivering mandatory directives, an absolute block must be established in advance of the trainset as soon as safe and practicable, and the trainset shall not exceed restricted speed until the absolute block in advance of the trainset is established.

(5) Where the failure or cut-out is a result of a defective onboard PTC apparatus, the trainset may be moved in passenger service only to the next forward location where the necessary repairs can be made; however, if the next forward location where the necessary repairs can be made does not have the facilities to handle the safe unloading of passengers, the trainset may be moved past the repair location in service only to the next forward passenger station in order to facilitate the unloading of passengers. When the passengers have been safely unloaded, the defective trainset shall be moved to the nearest location where the onboard PTC apparatus can be repaired or exchanged.

(c) The railroad shall comply with all provisions in its PTCSP for each PTC system it uses and shall operate within the scope of initial operational assumptions and predefined changes identified.

(d) The normal functioning of any safety-critical PTC system must not be interfered with in testing or otherwise without first taking measures to provide for the safe movement of trainsets that depend on the normal functioning of the system.

(e) The railroad shall comply with the reporting requirements under § 236.1029(h) of this chapter.

(f) The railroad and the PTC system vendors and/or suppliers must comply with each applicable requirement under § 236.1023 of this chapter.