After doing a little research, I can now tell you (basically) everything you ever wanted to know abo...

1. How does an aeroplane’s black box work?
After doing a little research, I can now tell you (basically) everything you ever wanted to know about
black boxes...
In the average commercial aircraft, you’ll find the presence of multiple (usually four)
microphones in the cockpit at any given time. They are located in the pilot and co-pilot’s
headsets, as well as in the cockpit itself. Not only do these microphones record conversations
between the pilots and cabin crew, they also record any ambient noise (such as switches being
thrown or sounds generated by technical issues). The microphones all connect to the cockpit voice
recorder (CVR), a master unit that stores the last 30 minutes of sound. The tape operates on a loop,
essentially erasing itself every half hour.
This device is known colloquially, but a little misleadingly, as the black box (it is usually quite
brightly coloured in order to make it easier to find in the unlikely event of an accident). Another
device also referred to as a black box, is the flight data recorder (FDR), which automatically records
data regarding the plane’s flight path, speed and movements in the air. Although the devices are
distinct from one another, the information they record goes to the same place and is used for the
same purpose, thus their shared name of black box.
In recent years, manufacturers have moved away from
magnetic tape-based CVRs and FDRs and towards solid
state technology boxes. These improved devices store the
relevant data on memory boards, which can hold up to
two hours of cockpit recording and 25 hours of flight
data. The solid-state devices are also sturdier than their
tape-based counterparts.
Crash survivable memory units (CMSUs), are large
cylinders that back up all the relevant data and are
designed to withstand extreme heat, pressure and violent impact. They are typically contained
within the box itself. In the more severe accidents, the CMSU is all that survives of the black box.
The black box, then, simply records all the relevant data before an accident occurs. This serves to
provide engineers with an explanation for a crash, as well as providing investigators and regulators
with the same information.
So there you have it, of course, a lot of information is stored in an aircraft’s black box (much more
than I’ve detailed here), but as a general example, that’s what it is and how it works. Hope that
helps.