Nepal plane crash

Context:

It is also called flight data recorder or cockpit voice recorder and it stores data about planes.
They reveal information which leads to information about the accidents of flight.
There are two different flight recorder devices the flight data recorder (FDR) preserves the recent history of the sounds in the cockpit, including the conversation of the pilots.
These can also be combined into a single unit.
These boxes are of a size of a shoe.
It is compulsory on every commercial flight or corporate jet, and are mostly on tail of aircraft.
The flight data recorder (FDR) records more than 80 different types of information such as altitude, airspeed, flight heading, vertical acceleration, pitch, roll, autopilot status, etc. cockpit voice recorder (CVR) records radio transmissions and other sounds in the cockpit, such as conversations between the pilots, and engine noises.

How are they identified?

Black boxes are a blazing, high-visibility orange in colour, so that crews looking for them at a crash site have the best chance of finding them. It is not certain how they got their nickname, but recorders are today the holy grail that investigators seek in their quest for answers whenever there is an airline accident.
The use of black boxes dates back to the early 1950s, when, following plane crashes, investigators were unable to arrive at a conclusive cause for the accidents. An Australian scientist named David Warren is often credited with their invention.

Surviving the crash

In the initial days of the black box, a limited amount of data were recorded on wire or foil. Thereafter magnetic tape was used, and modern models contain solid state memory chips.
The recording devices, each weighing about 4.5 kg, are stored inside a unit that is generally made out of strong substances such as steel or titanium, and are insulated from extreme heat, cold or wetness. The FDR is located towards the tail end of the aircraft because that is usually where the impact of a crash is the least.
To make black boxes discoverable under water, they are equipped with a beacon that sends out ultrasound signals for 30 days.