Black boxes on aircrafts and trains?

Question

how do black boxes work??

Answer 1

Rango is right, as usual.

Like most everything, event recorders evolved into their present state, which us quite sophisticated, showing a number of parameters.

After the speed recorder tape phase, the second generation devices recorded eight parameters; speed, brake pipe pressure, independent (engine brake) application, amperes to traction motors, direction of travel, power and dynamic brake.  The reason why there were only eight parameters is because these things used what was essentially an old “8 track” cassette recorder.  They could only store eight hours of data, before taping over the older information.

When checked, the tape cassettes were removed and taken to another machine that transcribed the information there on.  But, in order to get an accurate speed indication, the exact diameter of the wheel with the “alternator” (this device converted speed info into electronic impulse).  Not all wheels are the same size, due to wear or having been re-trued due to flat spots.  Here, a portion of the tread is actually ground away.

The person removing the tape had to take a measurement of the wheel using a piece of equipment made for that purpose.

It would be placed on the outside of the wheel, and measured the length from the “witness groove” (Check out some loco wheels when you get a chance.  The witness grove is a groove cut into the wheel on the side during manufacturing) and the beginning of the tread.  These measurements were made to 1/32nd of an inch.  Doing so allowed the person to calibrate the machine that would read the tape.

Primitive, but workable.

This of course has morphed into the digital devices in use today.  The parameters are many and record nearly everything, headlight, bell whistle, etc., etc.  You can’t get away with anything.

Not all locos had event recorders on them.  When a derailment would occur, the first order of business was to search the locomotive numbers that were equipped and see if any were in the consist of the train that derailed.

But, you could always get the truth from an engineer about his train handling, whether the consist had an event recorder equipped engine in it or not.  I spent a short time ('84-'87) as an RFE working with these things.  When I would head for a derailment site, I always made sure I had a blank cassette with me.  Before I began questioning the engineer, I always made sure he noticed the cassette by taking it out of my briefcase and laying it atop the control stand.

Worked better 'n truth serum...

Answer 2

Event rocorders on railroads record most operating functions of the locomotive, for years it was nothign more than a paper reel attatched to the speed indicator, called the speed tape.

Now they are pretty extensive, they record power and brake application, horn, whistle, headlight, speed and running time.

The do not record converstaions within the cab although some railroads record all radio conversations.

An old saying among railroad workers is the the RR officials after a derailment would trip over broken bones to get to the speed tapes.

I am really not qualified to answer about airplanes other than what is frequently in the news, and they do record conversations in the cockpit, I have no idea what other functions but my guess is that they are also pretty extensive.

Answer 3

They are recording devices that collect several channels of data at the same time.  Some make speech records of radio communications in addition to recording speed, mechanical data like engine performance and they record failures or sudden changes in direction.  Some data streams are only collected after a failure has been signaled to the recorder.

The data recorders are typically placed some where they are less likely to be damaged, or lost, in the event of an accident.  They are protected in a metal case and many times painted bright orange to make them easy to identify.

See these websites:

http://en.wikipedia.org/wiki/Flight_data...

http://en.wikipedia.org/wiki/Flight_reco...