Which aviation safety tool monitors cockpit actions and environment?

The Cockpit Voice Recorder (CVR) is designed to monitor and record cockpit conversations and ambient sounds within the flight deck environment. This tool captures voice communications between the flight crew, as well as any non-verbal sounds that could provide insight into the cockpit's operational context during flight. By recording these audio inputs, the CVR plays a critical role in accident investigations, as it helps to reconstruct the sequence of events leading up to an incident and provides valuable information about the crew's actions and interactions.

In contrast, a Flight Data Recorder (FDR) records flight parameters related to the aircraft's performance, such as altitude, speed, and heading, but does not capture the verbal communications or ambient sounds from the cockpit. The Transponder is primarily used for navigation and air traffic control purposes to communicate location and altitude to ground radar, lacking the capacity to monitor cockpit actions. The Emergency Locator Transmitter (ELT) is designed to emit distress signals in the event of an accident; it does not provide insights into cockpit behavior or communications. Thus, the CVR stands out as the specific aviation safety tool focused on monitoring the dynamics of the cockpit environment.