A train will be considered to have a train control apparatus failure(failed train) when any component of the train control apparatus fails to operate as intended, such as:
The audible indicator fails to sound when required or continues sounding when not required.
The speedometer is inoperative reading 0 mph when the train is moving, or there is a continuous no motion(v zero) indication.
It is necessary to operate the cut out switch for the cab signals, ATC, ATS, or any other component of the train control apparatus, except when necessary for operation in MBS.
Damage or fault occurs to any part of the train control apparatus.
The train experiences continuous cab signal flips
A train will also be considered a failed train when the train receives cab signal indication(other than a flip) that is not in conformity with fixed signal indication or observable track occupancy or track conditions.