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Guest Colins2

Why do pilots use Nautical Air Miles?

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Why can't they just use regular statute miles? This way, when you read a flight plan, you can tell the real distance from your next waypoint as if you were driving in a car.Thanks,Chris

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ChrisBecause Nautical miles(nm) are related directly to the size of the earth. 1 second of arc on a great circle equals 1 nm. Therefore, every 60nm you travel, you've changed your position by 1 degree. 360 degrees times 60nm equals 21,600nm, the circumference of the earth.Andrew Luck18 miles SW EGSH

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ok - so when pilots want to find out how far they have traveled in statute miles, they have to do the math on paper, because the distance in statute miles will be shorter - correct? Also, all the indications of distance are in NAM for FLY2 right? This is what I should use to plan my fuel needed? ThanksSincerely,Chris

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Chris,Pilot's generally aren't interested in statute miles.They are only used in a handful of countries anyway, the rest of the world uses kilometres.Anything to do with boats or planes, from the smallest trainer to the 777 is done in NM. Any sim will also work in NM.A statute mile is 5280 feet and a NM is 6077 feet (avg) therefore the distance in statute miles will be a higher number.Colin

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ColinI flew one Piper with the ASI calibrated in MPH instead of knots. A complete pain.Andrew Luck18 miles SW EGSH

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Many older GA aircraft have airspeed indicators calibrated in statute miles rather than knots. It is a pain, since surface winds, winds aloft, and ATC all use knots. Even DME speed readouts are in knots.John

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Andrew / John,Now you come to mention it, I have vague recollections of an old Stearman calibrated in MPH, but I may be wrong, it could've been another one.Please note, however, that I used the word 'generally' in my post and that is still true :DColin

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Pilots don't need math to convert nautical to statute or statute to nautical. The E-6B rotarty flight computer has markings for that conversion. We have better things to spend time on in the cockpit, like keeping the plane in the air. ;) They're ussually around $26 at a pilot shop if you get the metal ones, or you can get the cheaper cardboard ones around $12. Depends on how serious you are about your virtual flying though. Hehe.John S. MorganReal World: KGEG, UND Aerospace Spokane Satillite, Piper 28-161, Student 35+ hours.Virtual: Fly!II, KPHX, MidCon, PMDG Boeing 757-200

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After all,I don't even know why and how Statute Miles came around. I have never converted NM do SM in may life. Since I'm Brazilian I'm acostumated to think in KM and even though I rarely convert NM to KM when Flying.Does any one know what is around the existence of SM? It will be good to understand that.Regards to allJJLobo

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G'day Andrew,:-eek :-eek :-eek:-) :-lolhhmmm? Love your scenery work; great stuff. Thanks for sharing with us.Cheers,Roger @YSSY

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G'day JJLobo,I think we can lay the finger of blame squarely on the Romans for the mess so eminently characterised by the Imperial Standards. The Poms (English) did nothing but further confuse the issue.Thank heavens Napoleon had a bit more sense. :-) Our government here in Australia converted us to the Systems International standard several decades back.Originally an INCH was the width of a finger or three barleycorns laid end to end. The FOOT was the length of a soldiers foot.The YARD was the distance from the tip of the nose to the tip of the thumb on an outstretched arm with the head facing forward.The MILE was a thousand paces (a pace being 2 steps ; left foot then right foot). This is obviously a very loose standard as there is no common factor connecting all the measurements.As time progressed attempts to make a more exact/accurate standard resulted in a foot arbitarily being made exactly equal to 12 inches. A yard became 3 feet and a mile became 5,280 feet.Thus;12 inches = 1 foot3 feet = 1 yard22 yards = 1 chain10 chains = 1 furlong8 furlongs = 1 mile (statute)You can see its some time since I went to school :-lolCheers,Roger @YSSY

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