When would a train operator become aware of a third rail power failure during braking?

A train operator becomes aware of a third rail power failure when trying to start after the station stop because this is when the train draws power from the third rail to begin moving. During this phase, if there is a power failure, the operator will notice that the train is unable to accelerate as expected. The application of power is crucial during this moment, and if it is not available, it will manifest as a failure to start the train.

Awareness during other phases, such as approaching or stopping at the station, may not indicate a power failure because the train can still coast or come to a stop using momentum or brakes, regardless of third rail power availability. Additionally, during the journey to the station, the train may still receive power and function normally, giving no indication of an impending issue with the third rail until an attempt to restart is made.