Kms versus feet

[Guest Flygirltake2]

Here goes my first probably silly question.... can someone please tell me why distances from cloud are measured vertically in imperial feet and horizontally in metres?

 

 

[Brett]

Australia is still not sure if we use imperial or metric ,,,ask any machinist

 

 

[Guest Flygirltake2]

It is so illogical!!!!

 

 

[Guest Decca]

Has it anything to do with ICAO? (standardising western aviation) I know this is only answering a question with another question, & I should do some checking. But our altimeters & IVSI's are in feet & Feet per minute, while other horizontal distances are in metres, such as runway lengths. I'm also sure that China (possibly others) use metric altitude.

 

Brett you're right. I had both a financial & active interest in a fastener outlet in Melbourne, & we stocked & sold more imperial fasteners than metric during the 80's & 90's.

 

Regards, Decca.

 

 

[Admin]

I was up at the Mitre10 hardware store the other day buying some bolts and they told me that they are starting to slowly phase out stocking a lot of the metric range and broadening their range of imperial ones...I thought that weird

 

 

[Guest Ginger]

I vaguely recall that the Russians are metricated too.

 

I notice that the flight manual or the Sportstar has two versions of each performance table, one metric, the other imperial. The Sportstar is from the Czech Republic, part of the old Soviet controlled Eastern bloc.

 

I suspect we have to suffer this dogs breakfast of aviation measurement units because of the overwhelming influence of the Land of the Free and the Brave.

 

They probably argue that to convert to metric would be confusing etc, howver it is already confusing enough and probably contributes to the odd navigation error incident as well as add to pilot load.

 

Since the mess we are all dealing with now makes us experts in conversions, it shouldn't be to hard to convert to metric.

 

When I buy a new aircraft I am sure I would carefully weigh up the possibility of ordering it with metricated instruments

 

 

[Guest ozzie]

The French like to really confuse. All the hardware in aircraft like the Trinidad and Tobago are metric. Instrumentation US works in feet and MPH, Europe in meters and KPH and the Poms and us prefer knots and feet.

 

To get back to Flygirl2s original question. it was considered to expensive to change the dials on altis and VSIs and ASIs so stuck to the original imperial measurement.

 

some smarty found a formula to keep inches of merc and kilopascals the same . Horizontal measurements for clearances from cloud, runway lengths, ect was changed to metric to keep the metric conversion board happy.

 

So how do you want your fuel, kilos. pounds, imp gallons, US gallons, or litres.

 

A cessna handbook says US gallons, The boffins have relabled the marked quanity at the tank filler to lts and the flightplan wants kilos/pounds and the bowser dispences in litres. and the guy in the tower wants duration.

 

really if you fly in imperial and jump into a metric instrumentated aircraft it should not be a real problem as the needles point to the same place in stall cruise and vne. same with the alti. just the dials have changed green and red texta is a quick fix.

 

ozzie

 

 

[w3stie]

Yes, I think it is the yanks' fault. According to Wikipedia there are only three countries in the world that have not adopted the metric system. Liberia, Burma and the good 'ol USofA. Draw your own conclusions from that!

 

 

[hiperlight]

Here is something to think about:

 

why do most people in this country persist in the use of kilogram, instead of

 

Newton, as a unit of weight. Kilogram is a unit of mass.

 

w = mg (9.8N = 1kg x 9.8m/s/s). So the weight of a mass of 1 kilogram is 9.8 Newtons

 

In the USA pound a unit of force and slug is a unit of mass.

 

So 32.2 pounds = 1slug x 32.2ft/s/s and the weight of 1slug is 32.2pounds or 143Newtons.

 

The foregoing is based on 'g' (acceleration due to gravity) being 9.8m/s/s or 32.2ft/s/s.

 

Bruce

 

 

[Guest Ginger]

If you go to the Metric Conversion Board site & do a search on Aviation you can find a piece where the US forced Aust/NZ to link their metrology systems to the USA in order for Australian maintenance organisations to have the authority to work on US produced aircraft.

 

Eventually the USA will have to follow the rest of the world. That is, as their relative influence declines. Particularly against the predicted trade ascendancy of China and India.

 

In Australia it was estimated that metrification gained us about 3% improvement in productivity. The US will be looking for that in order to keep up. In short, market forces should eventually fix the problem.

 

In the meantime as long as we buy US & British aircraft we will have to put up with the mess.

 

 

[Guest pelorus32]

Someone suggested that the "land of the free" is part of the problem and that is true. When dealing with POHs from Europe they are in metres and km/h weights in kg and volumes in litres (though in Italy they are very comfortable with feet and km/hr). For the US they translate the POH into feet and mph and lbs not to mention US pints, quarts, and gallons and then for us it is of course feet and knots. Don't get me started on bars vs psi....and on and on it goes.

 

This is a major PITA and because the POHs tend to be updated regularly it becomes a real pain.

 

Regards

 

Mike

 

 

[Modest Pilot]

There are a number of ICAO standards. (grey blue etc) a country is free to choose what fits them best.

 

The CIS (Russia) use metres for everthing including altitude.

 

Terrible system you wind up flying Flt Level 10600m/ Flt Level 11200m

 

1000 gives all the require safty margins and easy to remember to boot.

 

 

[Guest Flygirltake2]

Aaaaaagghhhhh!!! it was a silly question..... Looks like we have to live with it.........

 

 

[Guest brentc]

The Russians use metres for altitude which was a contributing factor a few years back when a Russian airliner crashed into another airliner running on imperial altitude.

 

 

[Brett]

wasn't there also a bit of a slip up at NASA when the mars probe met the ground a little too soon in regard to a foot/metre slip up?

 

 

[Guest brentc]

I do recall that too. Seems nobody can work with the Russians.

 

 

[Guest ozzie]

Flygirl, it is not a silly question. rather the opposite. it has brought to everyones attention just how easy it can be to misinterrpret. remember the Canadian 747 that ran out of fuel after the refueller shortloaded after several mistakes were made in calculating the needed fuel requirement. It may not be that much of a drama to those of us who were around duing the changover it can still catch out the newbies.

 

no such thing as a silly questions. just silly boffins.

 

Ozzie

 

 

[facthunter]

FEET.

 

Flygirl, Altitude in feet is used in most of the world as far as I know, known exceptions being Indonesia and Russia.(there may be others) 1000' is used as separation (vertical) till you get up to higher altitudes. This is an appropriate distance and a good round number. Flight levels relate to feet. Those countries that use metric altitudes have to operate to the same physical level with the equivalent metric indication which is never a round number, so the opportunity for error or misreading is more likely. Nev..

 

 

[Barefootpilot]

You don't need to tell me about conversions. For one flight say I need 800 lbs of fuel. I then work out how much to add in litres. Put that much in the fuel tank write down fuel added in litres and fuel on board in lbs then convert that into KG's for weight before working out my balance in Inches. Yeah makes perfect sense!

 

No wonder some people use the theory if you can get the doors shut it will fly!

 

Oh and back on the thread Height is "almost" always measured in feet and distance in meters/miles

 

Adam.

 

 

[Guest Ginger]

For what it is worth,

 

 

 

 

 

 

 

 

 



I found the following (extract) (and a lot of other stuff) on the ICAO site

 

 

 

 

 



http://www.icao.int/icao/en/assembl/a36/wp/wp176_en.pdf

 

 

 

 

 

 

 

 

 



ASSEMBLY — 36TH SESSION

 

 

 

 

 



TECHNICAL COMMISSION

 

 

 

 

 

 

Agenda Item 31: Continued evolution of a performance-based global air traffic management

 

 

 

 

 



(ATM) system

 

 

 

 

 

 

RVSM IMPLEMENTATION PLAN

 

 

 

 

 

 

 

AND FLIGHT LEVEL HARMONIZATION IN CHINA

 

 

 

........ China will carry out RVSM in the Beijing, Guangzhou, Kunming, Lanzhou, Shanghai,

 

 

 

 

 



Shenyang, Urumqi and Wuhan FIRs and Sector 01 of the Sanya FIR at 1600UTC on 21 November 2007.

 

 

 

 

 



3.2 Bearing in mind that moving toward a single unit of altitude measurement remains a

 

 

 

 

 



long-term objective of ICAO and recognizing that no progress could be expected in the foreseeable future,

 

 

 

 

 



ICAO and states should harmonize the flight level allocation scheme when they implement RVSM in the

 

 

 

 

 



area where meters or feet is used for RVSM level allocation.

 

 

 

 

 



3.3 The Annex 2 — Rules of the Air should be reviewed and amended to provide the

 

 

 

 

 



harmonized cruising level tables expressed in feet and in metres for areas feet or meters is used for

 

 

 

 

 



altitude and elevation, and the metric RVSM FLAS should be based on the joint proposal by China and

 

 

 

 

 

the Russia Federation......

 

 

 

[Guest Ginger]

Adam, I can certainly relate to your message.

 

I havn't seen the flight manuals of your aircraft but it shouldnt be too hard to metricate the variious forms (Load & Balance etc) invlolved. You would need to format your own copy and use the convert function on Google. It would take about an hour per form. The new forms would have to be checked/verified somhow. Don't know about any leagal issues though

 

that

 

 

[Yenn]

Metric is great. Working in the construction and engineering industries it was so easy to change to metric. The only pity is we have not done it fully.

 

We ought to change to km instead of nautical miles. A nautical mile is basically 1 minute of latitude which makes it easy to work with on WAC charts which have degrees and minutes scale off, but their scale is 1:1000000, which makes 1mm a km. Easy to work out with any type of measuring stick, and I think a metre is 1/100000 of the distance round the world over the poles, so it could be easily used as the latitude scale on maps.

 

 

[Guest Rocko]

Hey Ginger

 

You mentioned eventually the US will have to follow the rest of the world...

 

But do they even know the rest of the world exists?

 

Saw an avialtion map from the US once....beyond the borders of the US were pictures of pirate ships and fabled creatures, and the words "Here be dragons!!"

 

Oh, except where the dragons had WMD's....then they're marked as terrorist dragons ;>

 

And there's nothing nastier than a Jihad dragon! ;)