# Cockpit Voice Recorder (CVR): Recording Scope, Activation, and Survivability

> Learn CVR architecture, activation logic, required audio channels, and recorder survivability features used in post-accident investigation.

- **Subject:** 022 — Instrumentation
- **Section:** 022-14 — Maintenance, Monitoring and Recording Systems
- **Topic code:** 022-14-01
- **Last reviewed:** 2026-03-27
- **Author:** Pablo Asensio Martínez
- **HTML version:** https://pilotsyllabus.com/en/instrumentation/maintenance-monitoring-and-recording-systems/cockpit-voice-recorder-cvr/

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The **CVR** is designed to record the audio environment of the flight deck to assist in accident investigations.

## Operation and Capability
*   **Recording Duration**: Historically preserves the **last 2 hours** of recording (loop recording). Newer regulations often mandate longer durations (e.g., 25 hours) for modern aircraft.
*   **Activation**: Automatically energized:
    *   In flight.
    *   On the ground with at least **one engine running**.
*   **Components**:
    *   **Area Microphone**: Typically located in the overhead panel to capture general cockpit sounds (switches, alerts, conversations).
    *   **Crashproof Recorder**: Housed in the aft section (tail) for maximum survivability, fitted with an **Underwater Locating Beacon (ULB)**.
    *   **Control Panel**: Includes a test button and an **Event Button** to mark specific moments on the tape for rapid retrieval.

## Recorded Information
According to **CS-25** / **EASA AIR OPS**, the CVR must record:
1.  **Radio Communications**: Transmitted and received.
2.  **Aural Environment**: Via the **Area Microphone** (cockpit sounds).
3.  **Interphone**: Communications between flight crew members.
4.  **Navigation Aids**: Audio idents (Morse code) from nav radios.
5.  **Public Address (PA)**: Announcements made by the flight crew.

*   *Note*: It does **not** typically record communications between flight attendants (inter-cabin stations) unless they call the cockpit.

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Free study notes from pilotsyllabus.com. Not a substitute for training at an approved ATO.