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Using feet not meters for altitude?

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Using feet not meters for altitude?

Old 26th May 2010, 20:22
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Using feet not meters for altitude?

Hi

Why do we use feet to reference altitude? I can't find any legal reference as to why I should use feet, can anyone point me to some legal "rule" that says we must fly with reference to feet for altitude?

I've tried ICAO Annex 5 and the ANO but can't find a suitable paragraph!

The only thing I can find is that the ANO is written with all altitudes in feet. eg the 500ft rule !

So what is stopping me flying in meters? What about the ATC side of things is there something that says they must operate in feet?

cheers
smithgd
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Old 26th May 2010, 20:25
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'cos we are British
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Old 26th May 2010, 20:36
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Russia and China use metres.

Feet for altimetry is probably a historical thing. Yanks kicked off aviation and they used it..

What's stopping you? Well, no one else in European airspace is using it and unless your avionics automatically convert it, you'll be forever looking up conversion charts when you should be concentrating on other stuff.

Why do the Brits use miles instead of kilometres...
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Old 26th May 2010, 21:38
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Why do the Brits use miles instead of kilometres...
'coz we invented the ruler!
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Old 26th May 2010, 21:41
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No - it's because you always have to travel less in miles. I is always further in km, but at least you can go faster.
...and, redsnail - we had feet before the colonies learnt to walk on them
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Old 26th May 2010, 21:50
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Because that's how it started, and we want to avoid sky/ground mismatch. Imagine new maps in meters and old instruments in feet...

BFC
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Old 26th May 2010, 22:09
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Interesting in this context to note that our seafaring counterparts have gone from fathoms to feet to metres for depth measurement, all in the last 50 years, but stick with nautical miles for linear measurement. And no, I haven't got an answer for Smithy.

Jack
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Old 27th May 2010, 00:09
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Just convention. With everything in the cockpit based on feet, metres is (are?) a pain, even with one of those clever digital metre altimetre thingies on the edge of my instrument panel.

Can't see linear changing from nautical miles for boats or planes for a long time.
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Old 27th May 2010, 03:04
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When ATC first got started, altitude was recognized as the ideal separation mode. With three-pointer altimeters, using one thousand foot separation was easy to read and apply, so that's it! Besides, meters is scurvy French idea.

Yes, the Russians and Chinese use meters, but different level assignment schemes AND Chinese RVSM is really silly.

GF
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Old 27th May 2010, 03:08
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Meters...OK for water meters and electric meters, not airplanes.
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Old 27th May 2010, 06:10
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Why feet?

As others have said, the world of aviation with the exception of the Chinese and Russians use Imperial measure for altitude. Simplicity of use and reducing the liklihood of "Murphy's Law" occurences dictates that we should all be using the same scale. It is even more confusing when uplifting fuel in any of three systems of measurement. Imperial gallons, US Gallons and Litres. Then, depending on what type of instrumentation you have it has to be converted to either lbs or kilos. Wouldn't life be easy if we were all on the same "tram".
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Old 27th May 2010, 07:24
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Russia and China use metres.

Feet for altimetry is probably a historical thing. Yanks kicked off aviation and they used it..

What's stopping you? Well, no one else in European airspace is using it and unless your avionics automatically convert it, you'll be forever looking up conversion charts when you should be concentrating on other stuff.
Actually not true except for pure IFR traffic

Gliders and ultralights at least in germany but probably in france and other countries in europe as well use metric units. I learned to fly that way (of course started flying at 14 in glider planes) and had to relearn quite a bit when i started my ATPL studies. Modern glass-cockpit style instruments offer both unit systems or can be easily switched between both.
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Old 27th May 2010, 11:19
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I think the nautical mile is important because it is one minute of change of latitude along a meridian (or along an arc of any great circle), so it is relevant to basic navigation methods. I suppose on another planet the nautical mile would have to have a different length...

Feet/metres etc are more man made references, without any relationship to a basic characteristic of the Earth.

Happy to be corrected...
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Old 27th May 2010, 13:11
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Well, a metre WAS, initially, one ten-millionth of the distance from the Equator to the North Pole .. but then, that idea got thrown out, as being somewhat elastic....

Metre - Wikipedia, the free encyclopedia
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Old 27th May 2010, 13:26
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I don't know we still use feet but 'descend to nine one four decimal four metres cleared ils approach' doesn't really sound right
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Old 27th May 2010, 13:53
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Mid Air Collision

Something in the back of my withered old brain is telling me that there was a mid air collision caused by one aircraft (Russian I think) being at the wrong height coz he mistook Feet for Metres

Put me out of my misery

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Old 27th May 2010, 14:30
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Oldfella

Just look up the Gimli Glider story to prove your point on mixing measures-volume and weight in that case.

GF
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Old 28th May 2010, 10:25
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Wasn't feet used because it's a part of a statute mile, and the earth's circumference is approximately 24,000 statute miles, (at the equator) and, I've heard, rotates once each 24 hour period, which conveniently aligns with my watch!

That's it then...

Cheers...FD...
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Old 28th May 2010, 11:51
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Actually, FD, 'feet' were used because they are on the end of your legs.
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Old 28th May 2010, 11:53
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To the OP: the legal reference you seek is UK AIP-GEN-2.1.
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