Flight Data Recorders (FDR) and Cockpit Voice Recorders (CVR), or “black boxes” are usually combined into a single unit and record different aspects of a flight.
The flight data recorder (FDR) collects and records dozens of parameters collected several times per second, including airspeed, altitude, heading, vertical acceleration, and pitch, as well as individual instrument readings.
The cockpit voice recorder (CVR) records the sounds in the cockpit, including the conversation of the pilots, as well as radio traffic, discussions with the crew and announcements to the passengers, and automatic computer announcements.
How Black Boxes Work
A black box works by emitting signals along with a beeping sound for 30 days without the need of any electricity.
A black box can be identified from up to 2-3 km away and can emit signals from the depth of 14,000 feet in the sea.
The Crash Survivable Memory Units (CSMUs) hold all the important flight and audio data of the plane.
The integrated controller and circuitry board (ICB) contains the electronic circuitry that acts as switchboard for the incoming data.
The underwater locater beacon (ULB) helps investigators to identify the location of the black box in the event of an ocean crash.
The batteries are designed for 30-day continuous operation and have a six-year shelf life.
Black Boxes Are Found At the Tail
Generally, a black box is installed in the tail of the aircraft.
The reason for this is because the least amount of impact is received at the rear of an aircraft, which makes it more likely that the black box will survive.
Black Boxes Have Limited Storage
A black box features memory boards that have enough storage space to record two hours of audio data for CVRs and 25 hours of flight data for FDRs.
Due to this limited amount of storage space, the data that a black box holds is recorded over.
Black Boxes Aren’t Actually Black
Due to its name, it’s only natural to think that a black box is black in color.
Black boxes are actually painted bright orange because it makes them easy to spot in the wreckage after a plane crash.
There is a reason why a black box is called a black box, though.
When first developed in the early 1950s, black boxes were painted black.
The crash-survivable memory units (CSMUs), which are the most important part of a black box, are housed in a solid-state box that insulates and protects them through three layers of materials:
Aluminum housing around the stack of memory cards
Dry-silica material to provide high-temperature thermal protection
A stainless-steel shell contains the dry-silica material
The components that make up the construction of a black box include:
A power supply
Crash Survivable Memory Units (CSMUs)
Integrated Controller and Circuitry Board (ICB):
Underwater Locater Beacon (ULB)
Good Luck Trying to Destroy a Black Box
A black box is virtually indestructible.
According to Scott Hamilton, director of Leeham Co., an aviation consulting company:
It would take a concentrated fire beyond its design strength, or an impact so high that it would be beyond what it could withstand to destroy a black box.”
The impact of a plane crash is not enough to destroy a black box, as it can withstand extreme heat, jarring crashes and an immense amount of pressure.
To make sure that a black box can survive a plane crash, manufacturers thoroughly test the device by first loading sample data onto the memory boards and then perform a variety of tests, including:
Crash impact testing: Shooting the black box down an air cannon to create an impact of 3,400 Gs.
Fire testing: Placing the black box inside a fire at 2,000 degrees Fahrenheit (1,100 Celsius) for one hour.
Static crush testing: Applying 5,000 pounds per square-inch (psi) of crush force to each of the black box’s six major axis points for five minutes.
Pin drop testing: Dropping a 500-pound weight with a 0.25-inch (0.64-centimeter) steel pin protruding from the bottom onto the device from a height of 10 feet (3 meters).
Deep-sea submersion testing: Placing the black box into a pressurized tank of salt water for 24 hours.
Salt-water submersion testing: Placing the device in a salt water tank for 30 days.
Fluid immersion testing: Placing various components of the black box in aviation fluids, including jet fuel, lubricants and fire-extinguisher chemicals.
The black box was invented in 1953 by the Australian researcher David Warren to record cockpit noise and instruments during flight to help determine the cause of airplane crashes and to help prevent them in the future.
However, it was only until 1958 that David Warren built the first combined FDR/CVR prototype.
In the U.S., in 1967, black-box rules came into effect, which was 4 years after Australia and 3 years after the UK.
The black box has undergone many design changes over the years, from using magnetic tape like a tape recorder to the use of solid-state memory boards today.
Helen Krasner holds a PPL(A), with 15 years experience flying fixed-wing aircraft; a PPL(H), with 13 years experience flying helicopters; and a CPL(H), Helicopter Instructor Rating, with 12 years working as a helicopter instructor.
Helen is an accomplished aviation writer with 12 years of experience, having authored several books and published numerous articles while also serving as the Editor of the BWPA (British Women Pilots Association) newsletter, with her excellent work having been recognized with her nomination of the “Aviation Journalist of the Year” award.
Helen has won the “Dawn to Dusk” International Flying Competition, along with the best all-female competitors, three times with her copilot.
