Flight data and cockpit voice recorders
Navigation · Chapter 34 · DGCA CPL and ATPL
Where the recorders are and how they survive, what the FDR and CVR record, when they run, how long they keep, and when you may fly with one broken.
Remember
- Red/orange crash-proof boxes at the rear (under the fin), each with a water-activated ULB.
- FDR via the data acquisition unit: time, attitude, speed, altitude, heading, g, thrust, flaps…; EVENT = bookmark.
- CVR: flight-deck radio, interphone, PA, area mic. Erase only on the ground, engines off, brake on, ≥ 2 s.
- AUTO: first engine start to 5 min after last shutdown.
- FDR 25 h; CVR 2 h (≥ 30 min older/smaller). Dead FDR (European rules): ≤ 8 flights, ≤ 72 h, CVR working.
Where are the recorders, and why are they built like that?
Two boxes at the back
- At the back • Two crash-proof boxes, painted red or orange so they are easy to find, at the rear, usually under the fin • The FDR (flight data recorder) keeps the numbers; the CVR (cockpit voice recorder) keeps the sounds. Both help find the cause of an accident
- Found under water • Each has an ulb: it starts sending ultrasonic pings when it gets wet, for at least 30 days (90 on newer ones) • Searchers listen for the pings to find the box under water
Where does the FDR get its data, and what does it keep?
What the FDR records
- The data unit • A flight data acquisition unit gathers the signals from the sensors and feeds them to the FDR
- The must-records • Every FDR must record: time, attitude, airspeed, pressure altitude, heading, normal acceleration, engine thrust, flaps, spoilers
- Bookmark • The event button puts a bookmark in the record, so a moment can be found later • It erases nothing
What does the CVR hear, and how is it erased?
What the CVR records
This lesson is part of the Navigation plan. See plans
When do they run, and how many hours do they keep?
Running and keeping times
This lesson is part of the Navigation plan. See plans
Test yourself on chapter 34
Test yourself
This lesson is part of the Navigation plan. See plans