The phrase "black box" sounds of airtime in two cases: when the transmission is in progress, "What? Where? When? "And when something happens where the crash.
The paradox is that if the black box in the television show - it is indeed a black box in an airplane is not a box and it is not black. Flight data recorder (this is actually called the device) is usually made of red or orange in color and shape give spherical or cylindrical. The explanation is simple: the rounded form of better resists external influences inherent in the plane crash, and bright color makes it easy to search.
What's in the box?
Directly to the recorder, in general, the device simple: it is an array of flash memory chips and a controller and fundamentally differs little from the SSD-drive in your laptop. However, flash memory is used in the recorder is relatively recent, and now in the air set of aircraft equipped with older models, which use magnetic recording - on the tape in the tape recorder, or a wire, as in the very first tape recorders: stronger wire ribbon and hence, more reliable.
The main thing - all this stuffing how to protect: a fully enclosed housing is made of titanium or high-strength steel, inside is a thick layer of insulation and damping materials. There is a special standard FAA TSO C123b / C124b, which correspond to the modern recorders: data must remain intact in case of overload 3400G for 6, 5 ms (falling from any height), full coverage of the fire for 30 minutes (the fire from the ignition of the fuel in the collision of aircraft with the ground) and in deep water 6 km during the month (in plane crash in the water at any point in the world's oceans except the depressions, the probability of being in which a statistically small).
By the way, with regard to the fall in the water: recorders equipped with ultrasonic beacons are activated by contact with water. Beacon emits a signal at a frequency of 37,500 Hz, and this zapelengovav signal recorder is easy to find on the bottom, from where it is removed by divers or remotely operated underwater robots. On the ground, the recorder is also easy to find: find the wreckage and knowing placements recorders enough, in fact, just look around.
On the case be sure there is an inscription «Flight Recorder. Do not open »in English. Often there is the same inscription in French; may bear the inscriptions in other languages.
Where are the boxes?
In the airplane "black boxes" are usually located in the rear fuselage, which is statistically less and less often damaged by accident, as a blow assumes usually up front. Recorders on board a few - so instituted in aviation that all systems are backed up: the probability that none of them can not be detected, and the detected data will be broken - is minimal.
At the same time recorders differ also on the recorded data in them. Emergency recorders, which are looking after a disaster, there are parametric (FDR) and voice (CVR). Voice recorder saves besides talks crews and dispatchers also ambient sounds (of 4 channel recording time - the last 2 hours), and parametric record information from various sensors - from the origin, course, speed and pitch and ending with the back of each of the engines. Each parameter is recorded several times per second, and with the rapid changes in the frequency recording increases. Recording is cyclical, as in Car DVR, new data overwrites the oldest. In this case, the cycle time is 17-25 hours, that is, it is guaranteed to be enough for any flight.