It is actually quite useful that our units for speed, distance and altitude are all different, because that prevents confusion.

If we hear an instruction in feet or flight level, we know it refers to altitude. Similarly; Knots = speed, miles or nautical miles = distance, Kilometers or meters = visibility.

Be careful what you wish for: If it was ALL in meters, can you imagine the potential confusion?:- "Speedbaby 123, descend altitude four kilometers to be level four zero kilometers before Brookman's Park, speed four zero zero kilometers per hour, RVRs at Stansted four zero zero/four zero zero/four zero zero meters".

Think about also the extra RT time that would be involved in a busy TMA taken up by having to say 'kilometers per hour' each time instead of simply 'knots'.

What does in matter, fly an Airbus, it seems airspeed indication is an optional extra!

Would that be Gas, Electric or Water? := :*
Anyway, you have all got it completely wrong, Knots are for keeping Boy Scouts, Cubs, Brownies and Guides occupied when the Leader can't think of anything else for them to do. :p ;)

Actually, it doesn't. It locates itself in Earth Centered, Earth Fixed Cartesian coordinates, using meters as a unit. It *displays* its position in latitude and longitude entirely for your conveninece.

You are right; how could I have been so lax.

I meant to say "I locate myself using a pencil and a parallel ruler to mark a position on a chart showing latitude and longitude, while my GPS locates itself in Earth Centered, Earth Fixed Cartesian coordinates, using meters as a unit and then displaying its position in latitude and longitude entirely for my conveninece."

And then I would have checked my spelling, just to make sure I would escape all criticism, and corrected any errors that I noticed.

A yard is a meter!

Fine with me, you sell me meters, I'll pay you yards

1 yard = 0.9144 metre

You lose!

Capot could be right. Last I had a yard of ale, it was just 3'!
;)

There are 3 possibilities for what the yard was based on, and none of them encourages one to go on using it;

1. It's a double cubit. ("What's a cubit?" "Half a yard, stoopid".)

2. It was more or less the distance around a man's waist.

3 It was the distance from King Henry I (1100-1135)'s nose to his thumb, with his arm outstretched, or something like that. That's King Henry I of England, and some of France as I recall, perhaps wrongly.

The word 'yard' comes from the Old English gyrd, meaning a rod or measure

Enough already.

I'm with yotty on this. Fathoms. The original decimal system.
100 Fathoms = 1 cable. 10 Cables = 1 Nautical mile.
So, speed in knots, height in fathoms, vis in cables.

"XXX, you are cleared to descend to 300 fathoms, radar heading North North East by East, report established ILS for runway North West By North Port, RVR 1 cable."
What could be simpler?

Vessel speed at sea was measured using a chip log. This consisted of a wooden panel, weighted on one edge to float upright, and thus present substantial resistance to moving with respect to the water around it, attached by line to a reel. The chip log was "cast" over the stern of the moving vessel and the line allowed to pay out.
Knots placed at a distance of 47 feet 3 inches (14.4018 m) passed through a sailor's fingers, while another sailor used a 30 second sand-glass (28 second sand-glass is the current accepted timing) to time the operation.
The knot count would be reported and used in the sailing master's dead reckoning and navigation. This method gives a value for the knot of 20.25 in/s, or 1.85166 km/h. The difference from the modern definition is less than 0.02%.

there is the foundation of your measurement...

To the OP, I feel it disturbing that it disturbs you. It should though be globally standard, same goes for altitude and spoken language with ATC.

^this^
The old Imperial system is on its last gasps, as it should be. Aviation is the last stubborn area where it's hanging on and I hope that it transitions as quickly as possible to full metric.

Though I would actually like to see Planck Units used, they make even more sense than Metric does.

Not to mention millibars, hectopascals, inches and mm of mercury. All still in use today in aviation, somewhere in the world...

What about TIME: Could we please have a year equalling 1000 days with 10 months of a 100 days and a week of 10 days. The World wasn't built for metric units but for aesthetics where a pint of beer looks and feels right and is what an average person wants to consume in any one session. The same applies to weights: a pound of anything is much more to the human scale than kilograms etc. Packing is another problem much easier to pack a dozen items (3x4 or 2x6) than 10. And why isn't the World a perfect circle rather than an oblate ellipse? In the World of computers it's binary so 1s and 0s and thus bits, bytes hexadecimal octal .....

I think the ancient Egyptians first divided the day into 24 hours, 12 hours of day and 12 of darkness. But the base of 60 (for time and compass directions) came from the Babylonian system of counting which they may well have inherited from the Sumerians. Many of our current methods of counting and measurement come from very ancient roots! Rather than changing them let's glory in their antiquity. Also, 60 is quite convenient as it can be divided in many ways.

Converting from Millibar to Hectopascals is pretty simple, being as they're the same.

Look folks - this is really simple.

Exactly 6,000 Years ago, the Creationistas say that we were made.

We were a bit confused, and so concentrated on our fingers and toes, and decided that base 10 could work.

We then discovered that the World was spherical-ish and created a flawed mapping system.

They saw that one could divide the oblate spheroid into segments, like the Oranges that they were enjoying when boiled with sugar and made into Marmalade.

Good result. It worked. But.

They didn't spot that Lines of Latitude might have been better replaced by choosing an East and West Pole and cutting the sphere into segments akin to those that Lines of Longitude do.

They would then have been able to work out the best way to eat a Grapefruit.

Notwithstanding this error, some bright spark realised that multiples of 12 offer more outcomes of subdivision than those of 10. Good point, and well made.

Then at some point (and I'd welcome some input from the Creationistas for an exact date) we noticed the stars and Sun/Moon/Planets, and made some notes. And with some sums worked a few things out so that we could guess our location.

A bit further along, Radio was created, (again, input welcomed) and some people (who turned not to be on our 'like' list) came up with "Ultrakurzwellen-Landefunkfeuer".

This was not good news.

But it was a turning point (sorry). Thereafter the electronic and radio based systems (with the exception of the simple RDF) relied on lines on maps for co-ordination which were entirely arbitrary. The 1980s gave us (civilians) electronics which would do their stuff and give us Lat/Long - but only thinking in 1/0s internally.

Today the gps system does not have a clue about units that we would use. They work out where we are and, in much the same way as we would say 'print' on some data, it stuffs it through the last bit of software to demonstrate some sort of recognisable position.

That, folks, is my take on the history of mapping.

Now if I could start.......

Just a personal opinion but, as already pointed out by several above, the current system is the best way to go. Using separate units of measurement for speed, height, RVR/viz etc. avoids misunderstanding and the speed with which the current, commercially orientated, flying schools are churning out new pilots these days I'm all in favour of as many built in safety devices as possible. Happy to see there is no serious effort by any major aviation organisation to change the present, western system.

What you say is true, but it's knots the entire truth!

So it was Stilton. time for Warp factor after all

Check Airman - thank you for making my point for me... Ahh, the USA, where even the paper is a different size and shape to the rest of the globe.

It's a de-facto Metric Unit
 

I'm surprised that someone hasn't raised the point that the Nautical Mile is ESSENTIALLY a Metric unit, being defined as EXACTLY 1852 M, and equal to 1 minute of arc of latitude. Degrees, Minutes, and Seconds are an integral part of the Metric system. I say essentially a Metric unit, see the extract from Wikipedia below, where, in red, it is noted that it is accepted for use in the International System of Units by the BIPM. It's equivalent in feet or other units is a surd.

Courtesy of Wikipedia - The nautical mile (symbol M, NM or nmi) is a unit of length that is about one minute of arc of latitude measured along any meridian, or about one minute of arc of longitude at the equator. By international agreement it is exactly 1,852 metres (approximately 6,076 feet).

It is a non-SI unit (although accepted for use in the International System of Units by the BIPM) used especially by navigators in the shipping and aviation industries, and also in polar exploration. It developed from the sea mile and the related geographical mile.

The nautical mile remains in use by sea and air navigators worldwide because of its convenience when working with charts.
- END Wikipedia quote.

The International Nautical Mile was established in 1929, adopted by the U.S.A. in 1954, and belatedly by the Brits in 1970 when they finally standardised and dropped their beloved 6080 ft Nautical mile (But it's legacy lives on in things like the constant of 38.94 instead of 38.9679 for Mach Number to TAS computation ~ some errors never die!).

A system that essentially provides for navigation, and as a bonus is an accepted de-facto member of the Metric system, is, I believe, more useful and appropriate than the distance that a Roman soldier could march in full kit between rests:\

Time to bury the milus and the mile with the cubit and other quaint measures.

Best Regards,

Old Smokey