So that the flight attendants can ensure we are both still conscious or, more realistically, awake. It is not common for both pilots to fall asleep at the same time, but it does happen. Our flight attendants check in every 20 minutes* so that, if we have fallen asleep, it should not affect safety.

Flight attendants must "check in" for their duty (often called a "sign-in") for several critical safety and operational reasons. Firstly, the airline must verify that the crew member is physically present, in uniform, and legally "fit for duty" (not fatigued or under the influence) before the flight can be cleared for departure. During this check-in process, they receive a pre-flight briefing from the Lead Flight Attendant or Captain, which covers essential safety information, emergency procedures, weather updates, and specific passenger needs (such as medical alerts or VIPs). This also ensures the aircraft meets the legal minimum crew-to-passenger ratio required by aviation authorities like the FAA; if a flight attendant fails to check in, the flight may be delayed until a reserve crew member arrives. Finally, it serves as a security measure, verifying the crew member’s credentials and ensuring that only authorized personnel have access to the aircraft and secure areas of the airport.