Units Was: Where is balance 280

It's particularly amusing that even countries that have adopted the metric system (i.e. all but the US) still use ft-kt-nmi for aviation.

Actually, you could leave the equipment operating in feet, but translate to meters for display to pilots and ATC. The problem is, as you said, the transition -- there are millions of pilots and hundreds of thousands of aircraft worldwide. A "flag day" is not feasible at that scale, and a dual-units period would be worse.

Canada's conversion to the metric system for fuel led to a catastrophic failure; google for "Gimli Glider". Visions of pilots flying into mountains at 1000m (when their altimeter showed them clear at 1200ft) is enough to keep the industry maintaining the status quo even if we know metric is "better". The change is not worth people dying.

We use Celsius here, though many of us have to convert to Fahrenheit for it to make any sense.

miles, trivial.

People on the ground, usually ATC folks, use statute miles, so that's what is reported. There are some controllers that are pilots, but I've met far more that refuse to ever get in any plane; in general they have no clue what X knots or Y nautical miles "feels like", just what it looks like on their radar scope (if they even have one).

Nautical miles are a completely stupid unit to begin with. Knots are about speed through a moving fluid. How far a vessel (either ship or aircraft) can travel in an hour at one knot varies depending on the speed and direction of the fluid, which is (almost?) never exactly zero. I'd rather ditch nmi entirely and use smi, but in most cases they're close enough that it doesn't matter which type of miles you're reporting. The margin of error in measurements is normally greater than the conversion factor.

S

-- Stephen Sprunk "Those people who think they know everything CCIE #3723 are a great annoyance to those of us who do." K5SSS --Isaac Asimov