Which of the following statements is true regarding cockpit voice recorders?

Cockpit voice recorders (CVRs) are designed to capture and store audio from a flight deck, primarily focused on conversations between flight crew members and communication with air traffic control, as well as any audible alerts or warnings occurring during the flight. The correct statement regarding cockpit voice recorders is that information older than 30 minutes can be erased.

This characteristic stems from the limitations on storage capacity inherent to CVRs. Typically, CVRs are constructed to overwrite the oldest audio data when the storage limit is reached, which allows for a snapshot of the most recent part of a flight's audio environment, generally retaining the last 30 minutes of recorded data. This timeframe is crucial for accident investigations because it retains the critical phases of flight immediately preceding an event.

The other statements are not consistent with how CVRs operate. They do not retain data indefinitely; rather, they have a finite storage capacity that necessitates the overwriting process. While CVRs record various inputs, they do not focus solely on audible warnings but encompass a broader range of audio input including conversations. Lastly, the idea that every flight must be recorded manually is inaccurate because cockpit voice recorders automatically begin recording at the start of each flight, without any requirement for manual operation.