CVRs

A cockpit voice recorder, or CVR, is a flight recorder that captures audio from the cockpit during flight. It records crew conversations, ambient cockpit sounds, and radio communications with air traffic control and other onboard systems. CVRs are typically part of a broader flight recording system and are commonly paired with a flight data recorder (FDR), which logs aircraft performance data.

Construction and placement: CVR units are housed in rugged, crash-survivable containers located in the aircraft’s tail or aft fuselage. They are designed to withstand high impact, fire, and immersion. Most CVRs include an underwater locator beacon that emits signals to aid search and recovery when the aircraft is submerged.

Data, duration, and access: CVRs generally retain the last 30 minutes to two hours of cockpit audio, depending on regulatory requirements and aircraft type. Modern commercial airliners often use longer-duration CVRs and multiple microphones to capture clearer crew voices and cockpit sounds. Recordings are time-stamped and can include selected radio transmissions. In an incident, investigators retrieve CVR data to reconstruct events; data is protected by tamper-evident measures and access is restricted to safety investigations.

Regulation and standards: International and national aviation authorities require CVRs on commercial aircraft and set rules for retention, maintenance, and safeguarding of the data. Standards are developed by bodies such as the International Civil Aviation Organization (ICAO) and implemented by regulators around the world.

Limitations and relationship to other systems: A CVR only records cockpit audio and does not provide real-time telemetry; it is complemented by the FDR, which logs performance data. Together, they form the core components of the aircraft’s accident investigation suite.