In the Monopulse Secondary Surveillance Radar (MSSR), what happens when the operational online channel fails?

In Monopulse Secondary Surveillance Radar (MSSR), if an operational online channel experiences a failure, the system is designed to ensure continued operation by promptly switching to a standby channel. The correct choice states that the standby channel will come online while the faulted channel goes offline, with the transition designed to occur within a maximum timeframe of 4 seconds.

This quick response is critical for maintaining surveillance capabilities without significant interruption, as radar systems need to continuously track and identify aircraft. The design ensures that any failure in the operational channel does not compromise the radar performance or the ability to gather necessary data on airborne objects. Hence, the system architecture prioritizes rapid recovery and resilience against channel failures, which is reflected in the chosen answer.