An aircraft’s orange-colored black box; the flight data recorder is on the left, the cockpit voice recorder on the right; underwater locator beacons are mounted on the front brackets
25 May 2020
Whenever a commercial airliner crashes, which fortunately has become rare these days, there is the inevitable search for the black box, the flight recorder that provides data on the last moments of the aircraft’s flight to crash investigators. And almost inevitably the news stories will point out that the so-called black box is actually, in fact, orange, painted that color to make it easier to locate. If that’s the case, why is it called a black box?
To answer that, we need to go back to the early days of electronics, when electronic devices were literally packed into metal housings that were black. An early example is naval, not aeronautical. In 1931 the old battleship USS Utah was converted into a remote-controlled target ship, and a 1932 article in Astronautics describes the remote-control system:
On the destroyer that directs the activities of the crewless U.S.S. Utah is set up a radio transmitter. [...] For the sending of control messages, there is located on the destroyer a little black box, with keys arranged like those on a typewriter. By simply pressing one of these keys, an operator can direct the crewless battleship to make a complete turn, lay down a smoke screen, blow its siren, or go full speed ahead.
(Ironically, the Japanese sank the target ship Utah in the attack on Pearl Harbor, 7 December 1941.)
To bring it to the world of aviation, there is this 1936 piece that was widely syndicated throughout the United States about a black box used in simulating air force bombing runs:
The camera obscura or “target station” is a portable black box mounted on four wheels and pulled by a truck bearing a two-way radio apparatus. As the bomber plane approaches, its swooping image is projected through a lens in the roof of the box, upon a large square of paper or chart, inside a small, light-proofed chart-room where the scorer traces the path of the plane and records hits and misses.
Nor was this usage restricted to the military. Here is a 1937 story about the first police radio-cars deployed in Jackson, Mississippi:
Within the next week or so, Jackson’s police cruisers will be at an instant’s call of headquarters, as final installation service is completed on the city’s shortwave broadcasting set and auto receivers, officials said.
The big black box with just a couple of dials and a few switches to identify it as a transmitter has already been placed in the police headquarters, and the connecting wires and other equipment are being attached and placed as rapidly as possible. Noel’s Auto Electric service has charge of the installation.
Of course, World War II saw the widespread use of sophisticated mechanical and electronic devices in aircraft and ships. The gun sights, as described in the 1943 newspaper story, on a B-17 bomber were controlled by a black box:
The second secret and the answer to that question have emerged together with a demonstration for newspapermen of the “automatic computing sight.” It is installed in the turrets of all Flying Fortresses. With this sight turret gunners are able to knock down anything with 1,000 yards by the mere twisting of a dial and the pressing of a trigger.
A small black box packed with intricate machinery and attached to the guns automatically sights opposing aircraft and directs unbelievably accurate fire to the target.
These devices were literally black boxes, but they also shared the characteristic of being sophisticated devices whose internal mechanisms weren’t understood by the users. Not only were they black in color, but they were black in secrecy and inability to comprehend how they functioned. After the war, the term black box came to be used to refer to any system that could be described by its inputs and outputs, without knowledge of exactly what the system did to achieve those outputs. This article from the 1949 issue of the Bell System Technical Journal puts it this way:
In principle, one needs no knowledge of the physics of the transistor in order to treat it circuitwise; any “black box” with the same electrical behavior at its terminals would act in the same way.
And:
We shall now take the purely empirical view and regard the transistor as a black box whose performance is to be determined by electrical measurements on its terminals.
But this last has little to do with flight recorders, which are called black boxes because of the history of calling any electronic device in a housing that, regardless of its color. The New York Daily News has one of the early examples of calling a flight recorder a black box in a January 1961 story:
The little black box in the world’s worst aviation collision spoke its long-awaited piece yesterday, helping explain why 134 persons died on Dec. 16.
The box—a flight recorder from a United Air Lines DC-8 jet—showed that a few seconds before the jet crashed with a Trans World Airlines Super Constellation over Staten Island, the jet—
1—Was traveling almost 300 miles an hour faster than it should have been going.
2—Was 3,700 feet higher than its pilot thought it was.
So that’s the explanation. Rather simple really; such devices were once colored black but no longer are.
Sources:
“Automatic Rocket Control Foreshadowed by Crewless Ship.” Astronautics, No. 19, May 1932, 4.
Oxford English Dictionary, third edition, September 2011, s.v. black box, n.
Pugh, Thomas and Neal Patterson. “Crash Jet Traveled Too Fast, Too High, Recorder Reveals.” Daily News (New York), 10 January 1961, C3.
“Radio Equipment Being Installed.” Daily Clarion Ledger (Jackson, Mississippi), 1 January 1937, 14.
Ryder, R.M. and R.J. Kircher. “Some Circuit Aspects of the Transistor.” Bell System Technical Journal, 28.3, July 1949, 367–400.
“Uncle Sam Is Practicing Aerial Bombing in Quiet.” Marshfield News-Herald (Wisconsin), 10 November 1936, 4.
“Where It Gets the Sting.” The Asheville Citizen (North Carolina), 5 July 1943, 4.
Photo credit: YSSY guy, 2015, used under a Creative Commons CC BY-SA 3.0 license.