The black box doesn’t look like you thought

This time, we will understand what exactly the “black box” is, and why is it called that if it is not its color at all? The term ‘black box’ refers to two separate devices: the cockpit voice recorder (CVR) and the flight data recorder (FDR). These devices are necessary in all flights and are usually located in the tail of the plane. Why there? Because this is where the chance of surviving an accident is the highest.

The location in the tail also allows the integrity of the devices to be maintained: the flight data recorders and voice recorders in the cockpit are built to withstand extreme impacts, but such a location gives an additional chance that the box will survive and provide critical information to researchers. Therefore, placing the black box in the tail of the aircraft has become an industry standard, and these studies support a decision based on factual data and not just on assumption or intuition. Of course, it is important to remember, on the other hand, the researchers emphasize that there is no “completely safe part” because survival depends greatly on the circumstances of the accident.

The information these boxes contain allows investigators to understand and pinpoint the probable causes of the accident and improve safety in the entire industry, whether it is pilot error, an external event, a malfunction in the aircraft’s systems, or a combination of several factors. The idea to create a device that would store flight data was born in Australia in the 1950s by Dr. David Warren. When Dr. Warren was six years old, his father was killed in a plane crash while flying from Tasmania to Melbourne. This incident led him to develop a unit that could record flight data and cockpit conversations to assist investigators after an accident.

The term ‘black box’ was first introduced in Britain during World War II, and was associated with the secret development of radar devices and electronic navigational aids in British aircraft. These secret devices were placed inside black, non-reflective boxes. Today, the black boxes are because of the color ‘international orange’, a color used by engineering and aviation to distinguish the items from the environment and make them easier to locate. Therefore, the term ‘black box’ has become imprecise, but it is known and common throughout the world.

Today the flight recorders are surrounded by strong stainless steel or titanium and insulated with a material resistant to extreme heat. In addition, they are equipped with an underwater receiver that produces an ultrasonic sound – ‘ping’ – to help rescue or locate teams, even at a depth of up to six thousand meters and for thirty days.

The recorder does not save all the recordings for life – but continuously saves only the last hours, usually the last two hours of conversations and movements in the cockpit. How does it actually work? The recorder constantly records what happens in the cockpit – conversations, external voices, alerts and more. As soon as the time comes (eg after two hours), the recorder deletes the first two hours and continues to record over them. In this way, a “time window” of the last few hours is always preserved, which allows investigators to understand what happened immediately before or during the accident.

This is actually a way to save the most important information, without having to store many hours of recordings, most of which are irrelevant. There are new and advanced planes that record more than two hours – there are models that record 4, 5 and even up to 25 hours of calls, in accordance with current regulatory requirements and company policies.

On March 8, 2014, a Malaysia Airlines flight took off from Kuala Lumpur International Airport to Beijing, China. The flight transmitted a final signal to the air traffic control system 38 minutes after takeoff, before communication was lost. During the search, the US Navy towed a fingerprinting radar, which is capable of detecting US military aircraft at a depth of 20,000 feet. After 30 days, the chance of finding the plane decreased significantly, because the black box finger stopped working.

As soon as the black box comes into contact with the water, there is a sensor that activates an underwater receiver that sends out an ultrasonic pulse. The human ear cannot hear the pulse, but submarines can easily detect it with the help of sonar equipment. Each black box is equipped with a battery with a six-year operating life, but once the receiver is turned on, it can transmit pulses for only thirty days.

In fact, each black box is equipped with two important energy systems: a general battery of the box, this is the battery that allows all the data to be recorded during the flight and saved inside the device. This battery is designed to work for up to 6 years without deteriorating significantly. That is, the box can record and function properly for years, even if the plane goes through many flights.

The underwater receiver (Pinger/Locator Beacon) – this is the receiver that is activated only when the box comes in contact with water. The receiver sends out ultrasonic pulses and after it is activated, it is only able to transmit for about 30 days, because the battery that activates the transmission is limited to that time.

Our black and orange box can withstand a load of thousands of G, a temperature of two thousand degrees, and even lie for weeks in the depths of the ocean and still, the story inside remains intact.