pilotdiscretion
Well-known member
- Joined
- Sep 16, 2005
- Posts
- 101
Listening to music or talk radio through your own headset leaves no incriminating evidence on the cvr, so that sounds acceptable.
The CVR is a very misunderstood piece of equipment for good reasons. We have little to no interaction with it and some in the industry feel that the less you know, the less you can mess with it when conducting shenanigans.
If the airplane you are flying was built in the past 20 years it will have a multi channel CVR. This means that it will record one stream for the cockpit area mic to pic up noises from the airplane. Three channels (four if you have two jumpseats) are dedicated to the intercoms. They record what each position hears and says into their boom mics. Other channels will be dedicated to comm radios on newer boxes. If you turn on the audio from a nav radio to identify a nav aid, the sounds are recorded on the individual pilots channel. If you plug an IPOD into the jumpseaters intercom then your obsession with the backstreet boys and show tunes is recorded. They know who listened to it and what they heard. Oxygen masks are also integrated in the system under the intercom channels.
If your curious about this go back and look at some NTSB CVR transcripts from the past five years and look at the identifiers along the left side of the page. It starts to make more sense how they came up with who said or heard what when you understand how the system works.
A few common misconceptions:
As the days go by and more airplanes roll off the assembly line more and more airplanes have 2 hour CVRs. If a 30 minute CVR breaks it's usually replaced by a 2 hour box because that's what gets produced as spare parts these days.
Every CVR has a battery back up, they last a couple of hours. If you pull the CVR breaker in the cockpit an audio tone is recorded on the CVR to tell investigators that the CVR is running on battery power. If you disable the CVR and have an accident nobody cares if you were innocent or if you used magical force powers like Yoda to save passengers lives, you're going down hard for trying to disable the box.
Saying "boy am I tired" before every landing doesn't work. NTSB investigations into fatigue are extensive and usually include interviews with your family and friends on your pre work habits. Not talking, yawning and heavy sighing are the signs of fatigue.
The CVR erase button in each cockpit doesn't not work when the airplane is weight off wheels.