Aviation history question - knots and feet in the East.

[opus_300]

Hello all. My first post here. A bit cheeky of me making this post on a Professional Pilot's forum as I'm not a proffessional pilot. But anyway, can anyone help me with the following questions.

At what point did eastern countries (Russia, China, Japan etc) change over from using metric units for altitude and speed to the current units of feet and knots? And do these countries still use metric altitude and speed units on internal flights?

I've done many websearches on this subject and drawn nothing but blanks. I cannot believe that these countries (anti-imperialists all) would have used imperial units like feet and knots back in the 40's or 50's.

A few other related questions. What is the current situation with the units used for measuring other parameters. For example: Are oil/tyre pressures measured in PSI or Kg/SqCm? Is fuel measured in gallons or litres? Is thrust measured in pounds or kgs? Or do the units used depend on each plane manufacturer?

Temperature I would imagine is certainly now measured in centigrade rather than fahrenheit.

Thanks in advance for any help with the above.

[Long Haul]

Russia and China still use meters for altitude (or, the rest of the world still uses feet). When flying Eastward, a typical flight level would be 10,100 meters with opposite direction traffic at 9600 meters and 10,600 meters. Western airline companies publish tables to convert their imperial altimeters to metric, or, on modern aircraft, there is a switch/button to display altitude in meters instead of feet. When referring to distance, Russian air traffic controllers use kilometers, and meters per second when refering to wind velocity, although many western aircraft make reports using nautical miles and knots, which seem to be acceptable. Temperature is in Celsius everywhere, although the USA only switched to this last year (or maybe the year before). The most confusing part, however, is when the altimeter setting (an indication of what the theoretical sea level barometric pressure would be, without which an altimeter reads incorrectly when comparing aircraft height to height above the ground) is given in different forms. In most countries the controllers issue the setting which would make the altimeter read field elevation on the ground (QNH); in some countries, however, like Russia and China (China is in the process of changing this), the setting given is the setting required to make the altimeter read zero when on the ground (QFE). Aircraft manufacturers can install metric or imperial fuel and oil quantity indications; both are used. Takeoff weights can be expressed in pounds or kilos, although airspeed is, I believe, is universally referenced in Nautical miles per hour, except for the oldest ex-Soviet aircraft. All in all a complicated system where the chance exists for a mistake should one let one's guard down. Years ago an Air Canada 767 ran out of fuel and made a remarkable power-off landing due in part to confusion over fuel quantity units, which had recently be changed at the airline from pounds to kilos.

[Oktas8]

Regarding lighter aircraft from USA - Cessnas, Pipers etc:

You will see many older (>5yrs) USA light aircraft using °F, and mph instead of kts.

Even the newest GA aircraft will still quote lbs for weight, and US gallons for volume. PSI seems to rule for tyre pressure. Atmospheric pressure (and turbocharger boost) will be quoted in inches of mercury.

Light aircraft from anywhere else in the world have gone metric except for altitude (feet), distance covered (nm, kts), and turbocharger boost (still inHg).

One day the US will catch up...

cheers,
O8

[opus_300]

Many thanks Long Haul and Oktas.

I'm quite surprised that there is still such a mix of units used in flying. I'd have thought that by now things would be much more standardised by now.

Anyway, between you, you've answered all my questions.

Thanks again.