If you ever watch an episode of “Air crash investigations” or had some classes about safety and avionics, you might know what a black box is. But do you know what it is and what it is made of?
In aviation, a black box is a device used to record flight data and cockpit voice recordings during an aircraft’s flight. The black box is typically located in the tail section of the aircraft, where it is less likely to be damaged in the event of an accident. The black box is painted bright orange to make it easier to find in case of a crash. It is made up of two components: the flight data recorder (FDR) and the cockpit voice recorder (CVR). The term “black box” was a World War II British phrase, originating with the development of radio, radar, and electronic navigational aids in British and Allied combat aircraft. These often-secret electronic devices were literally encased in non-reflective black boxes or housings.
The FDR records various data related to the flight, such as airspeed, altitude, heading, vertical acceleration, and the status of various systems on the aircraft. This information can be used to reconstruct the flight path and determine what happened in the event of an accident.
The CVR records all sounds in the cockpit, including conversations between the pilots, radio transmissions, and other ambient noise. This information can be used to help investigators understand what was happening in the cockpit leading up to an accident.
The black box, which was first used in 1947, serves to determine the causes of accidents and develop measures to prevent them. Since 1965, it became mandatory in the United States to install the cockpit voice recorder. Magnetic tape was able to record thirty minutes of ambient cockpit noise. Some early designs date back to 1953 and are attributed to Professor James J. “Crash” Ryan, a professor of mechanical engineering at the University of Minnesota from 1931 to 1963, who detains a patent for it.
Containing a wide range of information and cockpit conversations, the black box is designed to withstand even the harshest conditions, like high impact forces or extreme temperatures. They are typically required by law to be able to survive a crash and remain intact so that investigators can retrieve the data they contain. They have an average weight of 5 kilograms and are made of stainless steel or titanium. They can withstand high impact velocity or a crash impact of 3,400 Gs, this is equivalent with an impact with a concrete wall at 750 kilometers per hour (about 466 miles/hour). Moreover, they can withstand a static load of 2.25 tons for at least five minutes and temperatures up to 2000 degrees F (1,100 degrees C) for at least 30 minutes. The recorders inside are wrapped in a thin layer of aluminum and a layer of high-temperature insulation. In the event of a crash, the black box of a passenger plane is capable of emitting signals underwater for up to 90 days, allowing search teams to locate it even if it has sunk. It activates as soon as it comes into contact with water and begins to transmit signals.
In the end, flight data recorders are very useful in the case of an accident and are an important part of today’s investigations. If you want to learn more about black boxes, here is a video from Vox.