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> But there are constant, ongoing costs to having mixed units, potentially including lives lost (and certainly very expensive space probes lost). In engineerin

by mpyne 14y ago

> But there are constant, ongoing costs to having mixed units, potentially including lives lost (and certainly very expensive space probes lost). In engineering there is never an excuse for not knowing the units of measure of a value in use. That probe would have been brought down just as easily by mistaking a 'kg' parameter as 'g' as it would have been by mistaking a 'kg' parameter as 'lbs'. What's worse, in engineering there are multiple metric standards of measure (c-g-s, m-k-s, subatomic measures, etc.) There's no way around it, you have to know your units.

mikeash 14y ago
Excuses don't matter. The fact is that these mixups happen. And the probe would not have been brought down just as easily by mistaking 'kg' for 'g', because that would result in a number that was off by a factor of a thousand, and the result would be unlikely to make any sense. The meters/feet mixup that actually did happen could only happen because being off by a factor of 3.3 resulted in a number that still made basic sense, even though it was incorrect. There are documented instances of metric/imperial mixups crashing space probes and forcing airliners to land after running out of fuel in midair and such things. Are there any documented instances of similar metric/metric mixups?
- mpyne 14y ago
  > There are documented instances of metric/imperial mixups crashing space probes and forcing airliners to land after running out of fuel in midair and such things. As I recall, the Gimli glider came about because they were trying to switch to include metric units and had to change their procedure to do it, but didn't make the change in all places where it was necessary. This resulted in pilots using an Imperial conversion factor to try to calculate a metric fuel loadout, with disastrous results. http://en.wikipedia.org/wiki/Gimli_Glider#Refueling http://en.wikipedia.org/wiki/Gimli_Glider#Refueling ... this isn't exactly selling me on the idea that switching up all the units used in the U.S. is actually a good idea.
  - mikeash 14y ago
    This sort of error can happen any time you have mixed units, though, and as long as some countries insist on not using metric, the potential is there. The potential goes away once you switch, so as long as the costs for switching and for staying mixed are both finite and non-zero, it makes sense to switch now and get it over with.

by mpyne 14y ago

mikeash 14y ago

Excuses don't matter. The fact is that these mixups happen. And the probe would not have been brought down just as easily by mistaking 'kg' for 'g', because that would result in a number that was off by a factor of a thousand, and the result would be unlikely to make any sense. The meters/feet mixup that actually did happen could only happen because being off by a factor of 3.3 resulted in a number that still made basic sense, even though it was incorrect. There are documented instances of metric/imperial mixups crashing space probes and forcing airliners to land after running out of fuel in midair and such things. Are there any documented instances of similar metric/metric mixups?

mpyne 14y ago
> There are documented instances of metric/imperial mixups crashing space probes and forcing airliners to land after running out of fuel in midair and such things. As I recall, the Gimli glider came about because they were trying to switch to include metric units and had to change their procedure to do it, but didn't make the change in all places where it was necessary. This resulted in pilots using an Imperial conversion factor to try to calculate a metric fuel loadout, with disastrous results. http://en.wikipedia.org/wiki/Gimli_Glider#Refueling http://en.wikipedia.org/wiki/Gimli_Glider#Refueling ... this isn't exactly selling me on the idea that switching up all the units used in the U.S. is actually a good idea.
- mikeash 14y ago
  This sort of error can happen any time you have mixed units, though, and as long as some countries insist on not using metric, the potential is there. The potential goes away once you switch, so as long as the costs for switching and for staying mixed are both finite and non-zero, it makes sense to switch now and get it over with.