Inspired from another thread.
- A “black box” device has no controls for the operator to use. At most there might be an indicator lamp to show if it’s working or not and a “push to test” button to see if the indicator lamp is not lit because it’s burned out or if the device is not on. To turn on the flight recorders on an aircraft one turns on the electrical power to the aircraft. To turn off the flight recorders on an aircraft, one turns off the electrical power to the aircraft.
B) No user or local tech guy repairable components inside the box. Flight recorders are SEALED and only official certified and licensed by the FAA technicians can open them. And not just the regular FAA certification to fix an aircraft com or nav instrument, but you’ve probably got to be an FAA employee. It’s a “Black Box”, see? If it fails, you remove it, send it somewhere else to be repaired, and install another one. That’s the only local “repair” the line mechanic/technician can do.
And they’re painted bright orange in hopes they’ll be more visible than a black device as they search crews are looking through the remains of a burnt, crashed, aircraft.
“black box” is a sort of engineer’s metaphor for a device that does something - it takes inputs and gives outputs that are different but in some way dependent upon the inputs - but you can’t see what is going on on inside (or at any rate, you treat it that way, because you don’t need to know how it works, just what it does), and generally, you can’t alter how it works because it has no controls. Presumably it is “black” because you can’t see inside it. In process design, you don’t necessarily need to know how every step of the process is performed, or be able to control the parameters of the performance. Sometimes you just need to know what that step does. When that is the case, it saves time to treat that step as a “black box”.
An airplane’s black box fits the description fairly well. It is designed so that nobody, especially the pilot and other crew, can get inside it and tamper with its workings, or, indeed, control how it works in any way, not even turn it off.
As Ranger Jeff says, it is actually bright orange to give people a better chance of finding it after a crash.
I’m not sure how applicable this is, but “black box” is also used in testing software. A “black box” tester is basically testing the software by using it through the same interface a user would, and trying to make something reproducibly bad happen. The “box” is the software, and it’s “black” because the tester can’t see inside the box – they can’t see the internals as a software developer would. A “white box” tester is the opposite: a software engineer who can “see” inside the “box” – use software tools to perform unit tests on the code and find hidden flaws that customers might eventually see through tests using hidden knowledge that can’t be performed by a black box tester.
This is the same metaphor I was referring to, but it think it is used by engineers beyond software engineering, and probably predates computer software.
Agreed, I was providing additional context and I hope support for that idea. I doubt that software development came up with the term “black box” out of nowhere.
Orange is the [del]new[/del] old black box.
Yes. A “white” or “clear” box testing might take into account knowledge that the component makes extensive use of 32-bit integers for storing information and intentionally try to twiddle the inputs to find a way to make one of these overflow and trigger an error. If the tester knows that the system explicitly checks for Daylight Savings Time before processing an order, the tester might try to find “edge cases” to make it fail such as setting the system date to be the very day of the time changeover, etc. A “black box” tester might only know that the component is an order-taker that takes an inventory code and a desired item count (how many you want), and tries to place the order. The tester doesn’t know that the item count is stored as a 32 bit integer or that order processing has to be handled slightly differently during Daylight Savings Time.
I’ve also seen it used to describe items of computer hardware that are procured as ‘appliances’ - that is, you buy a ‘black box’ and plug it in to serve some function or other (NAS or IP telephony maybe) - and although you connect it to things, and it does stuff (and probably requires configuration of some sort), the device itself (hardware, OS and service layers) are not tinkered with.
In this particular usage, the boxes are in fact often black.
The word ‘black’ is often used historically to describe something wrong, strange or mysterious. Black sheep, black hole etc.
My WAG is that it was a layman’s term, or a term used by experts to a layman, to describe any complicated bit of machinery where is was not important for them to know the inner workings.
True, but I don’t think either of those examples are valid. The term ‘black sheep’ probably originates with actual sheep which were black - and black holes are black because light can’t escape.
Black Arts and Black Ops would be better examples.
To quote Sierra Leonean-Swedish musician Ahmadou Jah “I didn’t become what my parents wanted me to be, you can call me the white sheep of the family”.
We say “black box” when we really mean “opaque box”.
No user-serviceable (or visible) components inside!
Back in the day (up to 1988 when I last worked on DC-9s) some Flight Data Recorders still had repairable components inside. The roll of aluminum foil used to record flight data could be changed. If there was less than 5 hours left of the foil, they would open up the FDR on the aircraft and change it. I would inspect the FDR as part of the pre-flight inspection.
Not only are the ‘black boxes’ orange, but they also have reflective material on then to help find at night plus a radio beeper that is activated by water in case the aircraft crashes in the ocean, lake, etc.