Which of the following does not count as telemetry failure?

• A. Rear to front communication.
• B. Loss of telemetry signal.
• C. Data packet corruption.
• D. Time delay in reporting.

Answer: (A)

Telemetry is the automated reporting of sensor data from the train’s systems to a monitoring or control center. Failures in telemetry are issues with that data path: if the signal is lost, if the data packets arrive corrupted, or if there’s a delay in reporting. Rear to front communication is about passing information between crew members or parts of the train, typically through an intercom or manual chat system. That is not the sensor data path used for telemetry, so it doesn’t count as a telemetry failure. The other options describe problems directly affecting the data stream: loss of signal stops data from arriving, data corruption breaks data integrity, and time delay introduces latency in the telemetry feed.