I don't know if any of our aviation experts are still awake, but I have what is probably a stupid question. What triggers the activation of the cockpit voice recorder? Do the pilots turn it on when they suspect a problem or does something need to happen for them to go on automatically? In other words, how does equipment manage to capture the previous 30 minutes or so of conversation before a crash. I mean, these pilots don't know they're going to crash. I was told that the flight data recorders are on throughout the flight, and I'm not sure that the CVRs are too. It seems that I have heard investigators refer to the tape beginning while a problem was already going on. Somebody please set me straight so I can better follow our aviation threads. Thanks a lot.

-- Daisy Jane (deeekstrand@access1.com), February 21, 2000

Answers

Think "endless tape loop".

-- Charles Underwood Farley (c@u.f), February 21, 2000.

But why don't we hear more - why wouldn't they start talking a lot to tell the recorder what was happening or why don't they hear screaming. Its all pretty strange.

-- Sheri (wncy2k@nccn.net), February 21, 2000.

Mr. Farley: Thanks for your thought. Now, since all I know about tape is that from time to time, my VCR eats one, would you be so kind to indulge me and elaborate further? I must be having a brain cramp, but I still do not understand get it...

-- Daisy Jane (deeekstrand@access1.com), February 21, 2000.

Sheri, who ever said they didn't hear screaming? The last few minutes of that tape are probably scarier than any horror movie you will ever see.

-- Hawk (flyin@high.again), February 21, 2000.

Daisy Jane:

The Cockpit Voice Recorder varies somewhat depending on the plane. On the MD-80, it is an endless 30 minute loop that is on as long as the plane has electrical power. Each 30 minutes, it starts again and begins to overwrite the previous 30 minutes, which is why 30 minutes is as long as you'll be able to hear.

Newer aircraft like the the Boeing 767 and 777 have a digital recording system with a tape backup and you can have up to 6 hours recording time.

By law, cockpit voice recorder tapes are never released although the transcripts are. This is to protect family members from hearing some truly horrendous last moments being broadcast over the media.

Remember also that, in an emergency, pilots have one overriding job - fly the plane. Talking on the radio or even to each other is not a remote second priority. They're not trying to help us do a post- mortem but only trying to survive. Think also about the thousands of commercial flights that occur safely everyday and give thanks for the skills of our flight crews.

-- Jim Cooke (JJCooke@yahoo.com), February 21, 2000.

Mr. Cooke (As I slap myself upside the head)....I get it, finally!!! Thanks loads & loads. If my teenager was still awake, I could post a little illustration of a flashing light bulb in appreciation.

BTW, then your information means that in the future, the newer planes will offer more information by recording more of the flight?

-- Daisy Jane (deeekstrand@access1.com), February 21, 2000.

Daisy Jane:

Teenagers are always better at those snappy computer things than we old codgers I guess. :^)

There are a lot of changes with things like CVR's and FDR's. One of the things being tested now with some new Airbus aircraft is a constant data feed of voice, video, and instrumentation as the aircraft is in flight and being transmitted and recorded in real time on the ground. Not only will this permit a complete profile of the flight but it will allow adjustments to flight control sytems from the ground if there's a problem.

We live in wonderful times.

-- Jim Cooke (JJCooke@yahoo.com), February 21, 2000.

There was a pretty cool show on The Learning Channel once, about plane crashs. They played A LOT of voice recorders from the last minutes of many crashs. They also transcribed the words onto the screen. You'd be suprised. Most of the pilots continued trying to solve the problem calmly up until about the last 20 seconds. And there's a lot of exclaimations of "Oh Sh*t" and the droning "pull up pull up" of the ships computer. Not as much screaming as one might suspect, as they are trying to save their own as$es here.

-- kritter (kritter@adelphia.net), February 21, 2000.

For those of you who are interested in this sort of thing, search Amazon.com for this title:

"The Black Box: All New Cockpit Voice Recorder Accounts of In-flight Accidents," Edited by Malcom MacPherson.

It is a real page-turner -- I read it on a flight from Boston to Phoenix last summer.

-- semper paratus (still_here_with@my.pals), February 21, 2000.

[a href="http://www.airdisaster.com/index.html"]cockpit transcripts]/a]

-- kritter (kritter@adelphia.net), February 21, 2000.

Oh poop.

-- kritter (kritter@adelphia.net), February 21, 2000.

[a href="http://www.airdisaster.com/index.html"]cockpit transcripts[/a]

-- kritter (kritter@adelphia.net), February 21, 2000.

Oh fuck it. If you want to see it, you'll find yer own damned way there.

-- kritter (kritter@adelphia.net), February 21, 2000.

http://www.airdisaster.co m/index.html

-- Powder (Powder47keg@aol.com), February 22, 2000.