Ever got into an unfamiliar car and at the first intersection put on the wipers when you meant to indicate a turn? It’s because European cars have a reversed layout of wiper & indicator. An interesting feature of human adaptability that we adapt within minutes to the reversed layout.
That the wiper/indicator mix-up survives is a consequence of the low cost of the mix-up — usually a red face as the wipers start wiping when we wanted to turn left. But imagine if instead the mix-up was brake/indicators. Think of the problems that could result.
In aircraft a lot of effort is put into making sure that important switches or levers are unmistakable and not next to similar-looking but less important controls. (Or, in one case, so that the seat ejection lever is not close to another, commonly used, control.)
In other words, when things really matter we don’t design things so that windscreen wipers are confused with indicators. This design principle is well established.
Well, almost always.
Unmanned aerial vehicles (UAVs) are becoming common not only in war zones but elsewhere. They are controlled remotely and one crew configuration is a pilot and a camera operator sitting at separate operating consoles. A UAV crash in 2006 arose because the consoles were identical, but the functions of various levers were different depending on whether the console was in pilot or camera operator mode. In particular, the ‘engine condition’ lever became the ‘aperture setting’ lever.
Normally this didn’t matter, and there was an efficiency in only having one type of console, and a useful redundancy if a console stopped working.
In this crash, when the pilot’s console ‘locked up’ the pilot moved to the camera operator console. Unfortunately, the position of the aperture-setting, now-fuel-condition lever, happened to be the ‘fuel cutoff’ engine condition — and this passed unnoticed. Unsurprisingly, soon after the UAV crashed.
While the crash investigation concluded that the fault lay with the pilot, who didn’t use the checklist or check the engine status, others might wonder why something important like fuel cut-off would have a dual function in the first place.
As a coda: in the animated movie Monsters vs Aliens the president goes to push one of two large red buttons — one marked ‘Launch nuclear strike’, the other marked ‘Coffee’ — and, when stopped from pressing the wrong one, asks what idiot designed the system. “You sir,” answers one of his aides.