Using feet not meters for altitude?

[smithgd]

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! :ugh:

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

[BOAC]

'cos we are British

[redsnail]

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...

[parabellum]

Why do the Brits use miles instead of kilometres...


'coz we invented the ruler!:)

[BOAC]

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:)

[bigfatchris]

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

[Union Jack]

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

[deltahotel]

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.

[galaxy flyer]

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

[411A]

Meters...OK for water meters and electric meters, not airplanes.:}

[Old Fella]

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". :ugh::ugh::ugh:

[Denti]

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.

[alternateprocedure]

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...

[onetrack]

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 (http://en.wikipedia.org/wiki/Metre)

[Pera]

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

[bizdev]

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 :}

bizdev

[galaxy flyer]

Oldfella

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

GF

[Flight Detent]

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...:ok:

[BOAC]

Actually, FD, 'feet' were used because they are on the end of your legs.:)

[reportyourlevel]

To the OP: the legal reference you seek is UK AIP-GEN-2.1.

[onetrack]

IIRC, NASA lost an unmanned mission owing to a mix-up between metric and imperial units. In September 1999, 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.

Unfortunately, NASA, like so many other Depts, Entities, & Divisions... can't swap over to metrics overnight. Virtually everything they currently have, and operate with, is rooted in Imperial measure design. The 30 year old Space Shuttle design, is all-imperial measurements.

NASA have estinated the cost to convert fully to SI measurements is around $370M - almost half the cost of a Shuttle launch. Then, there's still the hangover of all the items that were built in Imperial sizes, that will still be around for a while yet. The unspoken thing is, that conversion to a full SI system, still isn't going to eliminate another possible disaster due to measurement system confusion.

[411A]

The unspoken thing is, that conversion to a full SI system, still isn't going to eliminate another possible disaster due to measurement system confusion

Exactly...therefore, don't change anything and save the funding for other things.....or....not spend at all.

Simples.
America is big enough, that actually, we don't care what the rest do.:E

[leewan]

Just wondering, if an airline is flying to Russia or China, is there any provision for the altitude in the FMC or FMGC to be converted ? I know there is MTR button in the 777, not sure of Airbus though.

[Itellbiglies]

Feet are used for vertical separation (including terrain & obstacles) and metres for horizontal separation (including viz) so as not to add further confusion.

[411A]

...and metres for horizontal separation

Ahhh, sorry, no.
Many countries (most actually) use nautical miles for horizontal separation.

[Tarq57]

-Feet for altitude/vertical separation, and in some countries, RWY length.
-Metres for RWY length in other countries, and horizontal visibility.
-Km for horizontal visibility when the viz is greater than 5 or 8 KM, depending on the application (Metar/Atis)
-Nautical miles for horizontal separation.
-Operating systems (in my tower) based on both Windows and Unix. Configured to both work differently.
-For pilots, US fuel gauges in US gallons, dipstick in litres or gallons (IMP or US), consumption figures can be in US or IMP gallons, pounds, kilograms or litres. Typically when I was flying quite a bit in the 80's, the bowser was in litres, the dipstick in IMP gallons, the gauges in US gallons, weights were in either pounds or kilograms....I became pretty proficient at quick mental conversions, and an ace on the E6B.

Not confusing at all. No problem.

[pilotusa]

Flight Detent wrote:
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...

So, you own the watch that controls the rotation of the earth! I was wondering who had it.

Please keep an extra battery handy.

[Itellbiglies]

So I was right then

[Denti]

So I was right then
Not quite, and realising that after 9 years is really a very slow reaction time.

[ShyTorque]

I use feet because that's what is written on my altifeeter.

[Atlas Shrugged]

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?


What a ridiculous question. Sounds like something imagined over one too many a glass of red. In no world does flying in meters when everyone in the airspace around you is flying in feet make any sense..... not even remotely!

:ugh::ugh::ugh::ugh::ugh:

[Denti]

What a ridiculous question. Sounds like something imagined over one too many a glass of red. In no world does flying in meters when everyone in the airspace around you is flying in feet make any sense..... not even remotely!

:ugh::ugh::ugh::ugh::ugh:
Funny thing is, i learned flying in meters, speed in km/h. In an airspace that follows the european standard (altitude in feed, speed in knots, visibility in km, runway length in meters etc). And i know there are over 30.000 pilots in this country alone doing that. Glider pilots in germany...

[Peter47]

It makes good sense using different units for different functions (altitide in feet, speed in knots, visibility in metres, etc) to avoid confusion. Similarly why do you climb and descend? Because you are less likely to confuse climb rather than ascend with descend.

On a separate issue, its just as well that tons aren't used (long, or short, a 12% difference).

Incidently do US airlines still use US gallons? They can be confused with imperial gals. Luckily I am not aware of imperial gallons being used anywhere.

[jimjim1]

Lecture over.....what do they teach youngsters these days????


Apparently not the difference between metre and meter. :E

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/224x225/metronome_d5539b883bc07902e090980ba6c688d802e5dac1.jpg
https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/275x183/multimeter_41ac4351237a0105136d0d3b99e35d4f6095be06.jpg

[dixi188]

When I started my apprenticeship in 1969, I was told by a college lecturer that we were going metric in 1971, but unfortunately we had to learn Imperial measure for the first two years, after that we would never use it again.
Last night I distinctly remember using a 7/16 inch socket on a 1/4 inch ratchet !!!!

[meleagertoo]

Apparently not the difference between metre and meter. :E



Well, aviation has yet to learn the far more significant difference between alternative (n) and alternate (v) - and steadfastly uses the wrong one!

[jimjim1]

using a 7/16 inch socket on a 1/4 inch ratchet !!!!

You could have used an 11mm one if you prefer to stay half metric wise.

Thank god the drive side hasn't changed.

One of the few small ones that are close enough for most purposes. I seem to recall that it works either way round.

= 11.125mm or if you prefer 11 1/8 mm :)

I have not checked but I seem to recall that 5/16 is v close to 8mm
Then you don't get a decent hit until 19mm and 3/4 which are also interchangeable.

I don't recommend this for work on Aircraft but it's OK for plumbing.

[jimjim1]

Well, aviation has yet to learn the far more significant difference between alternative (n) and alternate (v) - and steadfastly uses the wrong one!

You probably noticed this -

Alternate is
"another term for alternative.
"a novel set in an alternate universe"" (thanks google)

in North America.

That one is going to spread in the aviation trade!

Out of interest are Boeing (others?) Manuals localised to UK English or are they available only in American English?

[dook]

And another thing:

Why in Britain do we buy our car fuel in litres but measure fuel consumption in miles per gallon.

[nonsense]

I have not checked but I seem to recall that 5/16 is v close to 8mm
Then you don't get a decent hit until 19mm and 3/4 which are also interchangeable.

I don't recommend this for work on Aircraft but it's OK for plumbing.

12.7mm / 1/2" is close enough to 13mm, and vice versa, for working on old Morris Minis...

I'm 55, metrication arrived in Australia in my mid Primary school years, so I'm pretty much bilingual. I did my engineering degree ten years after leaving school, with a cohort who are now 45. They were notably less comfortable with imperial units, and the university went to enormous lengths to avoid anything non-metric, leading to some interesting odd numbers when doing practical classes on old steam equipment.

[AirUK]

If it ain’t broke, don’t fix it! Yes, it’s a right bugger’s muddle of units but it doesn’t really matter - ‘it just works’ (unlike Apple products these days!).

In the U.K. we should use miles per litre for gauging car fuel consumption.

Didn’t think Russia used metres for altitude anymore?

[Denti]

Didn’t think Russia used metres for altitude anymore?

Below transition they still do, or did they change that as well? Oh, and QFE, which is a right bugger anyway.