Flight Data Recorder – Cockpit Voice Recorder

Wing Commander Rajagopal

Black Box – Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR)

The black box is a crash-protected recording system that consists of the Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR). It records flight parameters and cockpit conversations to help investigators determine the cause of an accident or incident.

Flight Data Recorder (FDR)

Introduction to FDR

  • The Flight Data Recorder (FDR) preserves aircraft operational data for accident investigation.
  • It is also used for trend analysis and troubleshooting of aircraft systems.
  • The FDR typically records 10 to 25 hours of flight data and is stored in the aircraft “black box”.
  • The recorder is usually painted bright orange or red for easy recovery after an accident.
  • It is installed in the tail section of the aircraft to reduce damage from impact forces.
  • The unit is designed to withstand fire, heat, shock, and water immersion.

Components of FDR

  • FDR is mandatory for aircraft above 5700 kg all-up weight.
  • Main components include:
    • Recording system
    • Control unit (overhead panel)
    • Control unit (pedestal)
    • Data Interface and Acquisition Unit (DIAU)
  • DIAU sends data to the Aircraft Condition Monitoring System.
  • Aircraft Integrated Data System uses FDR data for trend analysis.
  • Airborne Communication and Reporting System may transmit data to the ground.

Control Panel of FDR

  • The overhead control panel manages both FDR and CVR systems.
  • GND CTL switch has two positions: ON and AUTO.
  • ON: CVR and FDR are continuously powered.
  • AUTO: Systems are powered under these conditions:
    • On ground with at least one engine running
    • In flight, whether engines are running or not
  • The EVENT button on the centre pedestal marks events for later analysis.

Parameters Recorded by FDR

Cockpit Voice Recorder (CVR)

Cockpit Voice Recorder (CVR) – Introduction

  • The Cockpit Voice Recorder captures cockpit audio for accident investigation.
  • It records the last 30 minutes of cockpit audio continuously.
  • CVR is housed with the FDR inside the crash-protected “black box”.
  • The unit includes an underwater locator beacon emitting ultrasonic signals.

CVR Automatic Activation

  • The CVR automatically switches ON when:
    • AC electrical power is supplied to the aircraft
    • At least one engine is running
    • The aircraft is airborne

Recording Channels of CVR

  • CVR records multiple audio sources:
    • Radio transmissions
    • Cockpit ambient sounds
    • Inter-phone communications
    • Aircraft system audio signals
    • Public Address (PA) system communications

CVR Data Handling

  • The CVR stores a rolling 30-minute audio loop.
  • An ERASE button allows deletion of recordings on the ground.
  • Erasing is only possible when engines are stopped and parking brake is set.