I always assumed that “flight level” kind of abstracted the feet away. Yeah, yeah, they’re hundreds of feet, but there’s not really any need to think of it that way. And of course flight level is (still? usually?) based on pressure, so not necessarily the exact altitude.
So what instructions do en-route and approach control give to my DTW to PVG Delta pilot once we enter China’s airspace? And are my pilots nav charts in feet, or meters for Chinese airspace? If I’m routed into holding do I have to worry about someone confusing feet and meters?
What about fasteners in cars (nuts, screws, bolts). My car (GM) is a mix of metric and english; which is why you have to have two sets of sockets/wrenches. I hope it finally ends up all metric-too confusing.
In September 1999, NASA lost an unmanned mission owing to a mix-up between metric and imperial units. Its $125 million Mars Climate Orbiter probe was destroyed because its attitude-control system used Imperial units, but its navigation software used Metric units. As a result, it was 100 kilometres too close to Mars when it tried to enter orbit around the planet.
The interesting thing is that Uncle Sam has decreed (in a 1988 Act of Legislation), that all U.S. Govt Depts, including NASA, go all-metric. The Inspector General has been hassling and pressuring all Depts to implement this change, under the enacted legislation.
I think that pilots just like to use what they are familiar with - after all feet or metres is just an arbitrary number really. It is similar to the argument about QWERTY keyboards.
How old is your GM? They should be 100% metric as far back as the late-90’s, with a couple of US-only models lagging only a few years.
GM was one of the early leaders amongst the American Big-3 in globalizing its entire supply chain and commonizing components, which is necessarily metric. The last thing I remember being non-metric in GM body shops (in 1996) was specifying sheet metal in mils, and only for non-global products.
Flight levels are still just round hundreds of feet. Metric flight levels are in round hunks of meters, and do not interleave neatly with units of hundreds of feet.
I don’t fly into Russia or China and have never been trained on the detailed nuances, so I can’t readily answer the exact questions with my usual degree of authority. Broadly speaking, at entry to metric airspace you’re given a revised altitude clearance expressed in meters and change your altimeters to read in meters and climb / descend as necessary to get to the correct ply. All charts, clearances, etc., are all in meters in China. I understand some parts of the former Soviet Union have a mix of feet in some situations as the leftover legacy of part of an effort to be sorta compatible with the rest of the ICAO world.
And yes, over the years accidents have happened due to feet/meters confusions. In the old days international aircraft that flew through metric airspace would have a second set of metric-calibrated altimeters installed. Nowadays we just push a button to effect the change in the GUI displays.
It’s a lot more than pilots’ preferences. We’re tiny cogs in the gigantic machine of international cooperation on meteorology, airspace management, aircraft operational regulations, aircraft design & equipage regulation, and finally actual operating technique.
Nothing changes without a decade of thought and planning, a decade to slowly re-equip the fleet and train everybody to the new standard, then a decade(s)-long phase-in of the new operating technique across a slowly growing swath of the world.
In a system with 8-nines reliability now, the folks in charge have to be very, very careful about not upsetting the apple cart and about avoiding unexpected adverse consequences.
I disagree. QWERTY keyboards and their alternatives are each linked to different physical objects of measurement.
I suppose physiologists or someone could come up with not one but two commensurable units of hand position, effort, and cognitive map relative to muscle memory; then I would agree.