Invention of the black box dates back after WWII and is connected with the recurrent mid air explosions of the De Havilland "Comet", the world’s first Jet Airliner.

On May 2nd, 1953, a British Comet aircraft, with 43 people on board, crashed near the village of Jagalgori, less than 29 miles from Calcutta. There were no survivors and the investigation board made recommendations for some design changes to keep the aircraft operable although it was already the second fatal incident.

A year later, in 1954 another similar aircraft blew up near the island of Elba, after taking off from the airport in Rome. Although the aircraft was still considered well designed, it fell in the Mediterranean killing 35 people.

Apart from a few fishermen, again there were no eyewitnesses. There were no survivors, no wreck, and above all, there was no data that could have provided any indication of the cause of the crash. Instead, there was immense economic pressure: the "Comet" with space for up to 36 passengers was the first commercially successful passenger jet in the world; it was supposed to take off again as soon as possible after all machines of this type had been shut down as a precautionary measure. Without knowing what had happened aboard the plane, experts considered a blast in the engine the most likely cause of the crash.

The turbines were reinforced, the "Comet" flew again - and crashed three months later from the sky again: this time it happend 30 minutes after the start-up also in Rome. The machine fell apart at an altitude of 10,000 meters. The debris was discovered shortly afterwards in the sea off Naples. It was an incredible tragedy - not just for friends and relatives of the 21 people on board, also the entire civil aviation was petrified. The new jet era that was about to bloom, seemed in danger. Experts worldwide were looking for possible causes for the series of mishaps of the first jet Airliner that supposed to be a pride and had it’s maiden flight only for 2 years.

The Idea;

Meanwhile, on the other side of the globe: David Warren, an aspiring chemist at the Australian Aeronautical Research Laboratories, specialized in aviation fuel and its potential hazards after graduation. As the "Comet" was soon to fly on the fifth continent, the 29-year-old suddenly found himself in one of the many commissions of inquiry.

But Warren was as perplexed as his colleagues, who could only speculate randomly. Turbulence seemed very unlikely, engine trouble appeared to be more plausible. The public was numb to all assumptions except to the terrorists and pilot error theories.

David Warren holding the original Minifon recorder

After all, David Warren continued the investigation in an obscure office far from the eyes of the public hungry for theatrical scenario. He had an idea how such accidents could be more easily elucidated in the future: The young man, who had lost his father at the age of nine by Australia's first major plane crash, was at a fair when he encountered a palm-sized recording device from Germany. The possibility of using a similar device to record the discussions in the cockpit and the main data of the aircraft for safe keeping got into his head. However his idea seemed out of place and he felt awkward trying to promote it among people who were desperately trying to solve the Comet mystery.

A Magnetized Steel Wire;

Warren told the commission of his idea - and was ignored. His boss couldn’t take his proposal into consideration because it was outside his field of work. He wrote reports, published them worldwide - but received no response. Finally, the inventor, who was advised by a manager who seemed to sympathize with his project begin to built in his spare time a prototype. Warren finished it în 1957 and called his device "Memory Flight Unit".

The construction was simple but careful designed: a thin steel wire, as used at the time in modern recorders, was magnetized by an electrically controlled writing head. In this way, the pilot's conversations and up to eight flight data per second could be recorded. After four hours, the loop began again, the data was overwritten. Warren encased the complete construction in a shockproof housing.

What the Australian did not know was the fact that Orville and Wilbur Wright had a simple flight recorder on their first motorized flights in 1903. Among other things, the device registered the speed and the speed of the propeller. However, the aviation pioneers did not think about securing the recorder against crashes. At an altitude of only a few meters there was no need.

Fear Of Spy On Board;

Much more sophisticated was the black box, which the Frenchman François Hussenot and Paul Beaudouin designed in 1939. The two engineers took an eight-meter-long film and stuffed it into a light-tight box. The negative strip was exposed during the flight via a mirror, which turned differently depending on height or speed. The data could be recorded in this way. The device was pitch black inside - possibly the reason why black boxes are still called black box.

The Hussenograph, as the engineers called their invention, had in practice, however, a whole series of disadvantages: each film could only be used once, after the mission it had to be replaced. The recorder did not record any conversations at all. Consequently, the device was rarely used, except on test flights.

Warren's rewritable steel wire did not have this problem. Yet his inventor caused a skeptical reaction in Australia, where no plane had crashed in years, or, even worse, indifference: The authorities saw "little direct benefit to civil aviation." The Australian Air Force predicted to hear from the cockpit only "force expressions instead of explanations". And the pilots warned of a spy on board: no plane would lift off Australian runways if Big Brother listened to it.

The Breakthrough;

However England took a different perspective. When the head of the British Aerospace Office heard of Warren's invention during a visit in Australia, he immediately took the inventor along with his recorder to London. The BBC was so enthusiastic that they immediately introduced the new device to television and radio. A little later came in England, the first commercial black boxes for data and calls on the market. Because of their shape and color they were called "Red Egg".

In France and Canada, experts were enthusiastic - only the US held back strikingly. Engineer James Ryan was developing his own black box there. However, he could not record speech.

Actually it was the recording of cockpit sounds that proved to be probably the best idea of David Warren. While mechanical problems can be detected relatively quickly on flights due to the large amount of processed data (modern flight recorders can store more than 1000 parameters), the noise in the cockpit should give many investigations a surprising turnaround.

"Thrust! Thrust! Thrust !!!"

A good example has been on the TWA 800, which exploded in the air in July 1996 east of New York. On the tape, less than a second before the crash, two insignificant noises were heard with a pitch of 400 hertz - a frequency that also powers the aircraft. It was only these tones that gave the investigators the idea that two short circuits in the fuel gauge must have exploded the main tank of the jumbo.

Sometimes the recordings simply show the desperation, confusion and helplessness of the cockpit crew. Such an example is the crash of a Boeing 757 of the Turkish charter airline Birgenair, in which 189 passengers going to a vacation were killed in 1996 off the coast of the Dominican Republic. A pilot tube was then clogged, it provided the autopilot and the crew wrong speed values. After a short time, the captain sounded completely confused and unnerved. "Thrust lever, thrust, thrust, thrust, thrust," he shouted to his copilot. And what I need to do?". When asked about the throttle, he exclaimed: "Do not close, please do not close." Despite the mechanical failure, the commission - based on the cockpit records - ultimately blamed the pilots for the disaster.

Meanwhile, the black box design evolved. After being made with metal wire at first, metal band afterwards, it began to use magnetic tape and keep up with the technology.

In the case of the "Comet", which was ultimately the trigger for the fact that almost all passenger aircraft today are equipped with black boxes, the research continued for more than 50 years, and for the whole world to acknowledge the fact that David Warren invented the Black Box, the same time lapse was required.