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Why Does Aviation Use Nautical Miles?

Apart from pilots and sea captains, most of us use either the Imperial or the metric system when calculating how far we need to get to where we are going. However, aviation navigation has adopted the ways of its marine counterpart, as it also travels across distances great enough to cross several latitudal lines. Not to mention to save air traffic control a great deal of potential confusion when communicating with international pilots. ( More...

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Dan Anderson 13
Not only are rankings a carryover from naval culture, but. so many more as well. Where are meals prepared? The Galley. The staff? Cabin Crew. The list continues.
Coalora 10
You can thank Pan Am for that.
jptq63 9
Do not forget the "Clippers"
padrooga23 35
I considered this question while sitting in the window seat on the starboard side, leaning heavily against the bulkhead. Then I noticed the no smoking sign on the overhead, glanced out the window across the aisle on the port side, when I finally decided to hit the head located in the aft section of the airplane.
Peter Koranyi 7
window = porthole?
padrooga23 3
I guess so, yes, of course I meant to work in something about the flight deck, but was distracted by the cabin crew.
Max Jones 5
Only on the port side, other side it's called the starboardhole!
Fred Ogden 12
Nautical mile is useful when traveling long distances around the globe. The concept originated in open ocean navigation. A distance unit equal to 1/60 of a degree is convenient for time/distance travel calculations, when the distance is described using geographical coordinates. It is a length based on an assumed Earth circumference. A nautical mile would be different on the Moon or Mars. Instead of calling it a nautical "mile", we could call it a "hexagesidegree". Feel free to convert it to m, ft. It loses its convenience immediately.

Q: If one has to travel 1.6 degrees around the globe at 120 knots (naut. mile per h), how log to get there?

A: 1.6 degrees=96 nautical miles. time= distance/speed: 96/120 = 48/60 or 48 minutes, because there are 60 minutes per hour, just as their are 60 n.m. in one degree.
True only if the degree change is a change in lattitude, directly north or south, or directly east or west at the equator.
Russ Brown 19
Because all pilots are "Naughty."
bobfiegel 7
There needs to be another response choice. Up, Down, and an added Up With A Groan. Lacking the latter I went with the superior former.

Retired 30-year Avionics Weenie
Having grown up in the Catholic Church, serving in the Navy and working in Aviation for decades, it comes down to one word— if I can borrow from “Fiddler on the Roof” , TRADITION.
womlliv 4
Well, Star Trek referred to star"ships", naval ranks dont know if correctly) and nautical terms and metaphors. So, was Gene Roddenberry Catholic?
Jasper Buck 7
"Having grown up in the Catholic Church"

Very sorry to hear that. I was raised in the Methodist church. Your church always beat us at softball. And your priest always had a basket of "cheer" at the parish fair. My church had none of that nor was lipstick or smoking allowed. No longer a Methodist.

"serving in the Navy" Even sorrier to hear that. I served in the Coast Guard. They made me fly a C-130, a HU-16 and C-123. The latter two are history. The 130 keeps on trucking.

"working in Aviation for decades" Glad to hear that. Now were talking. I started in aviation in high school. 1963 as I recall. Fueling and waxing airplanes on the weekends. 58 years later and still in the game.


Capt J Buck

ATP DC-9 B757 B767
Flight Instructor
Ground Instructor
Aircraft Dispatcher
A&P Mechanic
Air Traffic Controller
FAA Aviation Safety Inspector (Ops & Aws) ((Ret.)
FAA certified accident investigator (Ret.)
ICAO Panel Member
Aviation Safety Consultant

Rolf W. 4
Made my PPL 10 years ago. That’s it. No navy, no army, no C-130 (but even a C172). If someone’s to blame here, that’s certainly me. Oh, I even haven’t been in any church. #benicetoeachother
womlliv 1
Chase Tompkins -6
Your credentials would be more impressive if you weren't so arrogant!
Jasper Buck 13
I used to think that Lake Superior was pretty arrogant.
But if you think about it..
All the Great Lakes are completely full of themselves.

What do you call an arrogant criminal going down a set of stairs?
A condescending con descending


J Buck
padrooga23 4
"Superior, they said, never gives up her dead
When the gales of November come early"
Good one.
padrooga23 3
That's hilarious. I may have to borrow this.
Rich Boddy 3
Chase I swear to god if you talk shit to my homeboy Capt Buck like that again I will find you and make you wish you never had internet access to speak to him like that to begin with.
Ok Poor Boddy.
Mike Monk 5
The nautical mile is equal to one degree of latitude at the equator. It is therefore easier to measure a nautical mile on a nautical chart.
Early long haul aircraft were flying boats and the navigators used nautical charts to navigate and select suitable landing places - and the measure has stuck.
One knot is one nautical mile per hour and the unit of airspeed on all western aircraft (Chinese and Russian aircraft might be different)is the knot.
padrooga23 4
Your mileage may vary.......... Been dying to say that.
strickerje 2
Wouldn't it be a minute of latitude anywhere? The length of latitude units don't change with position on Earth like longitude.
JD Hassard 1
Think you meant longitude at the equator..
Mike Monk 1
No it is latitude, but I am wrong because it is on minute of latitude on the equator.
JD Hassard 1
Agreed, on the equator yes. It’s that slices, and wedges thing. Have a great day.
Thanks both, for a discussion without parallel. (Sorry folks, it's been a quiet morning here in the UK).
OK, I lol'd.
Flight Lane 11
Th neutical mile is the most natural distance: on a long and flat beach you can measure one degree / 60 -> this is one nautical mile.

1 meter = 1 / 40 000 000 on the equator of the Earth. Can you measure the length of equator ? The shape of the Earth is "geoid", not a perfect globe.
Sorry for my poor english.
Tom Zaidman 3
On French ships there was only one captain and on todays French registered comercial aircraft there is only one captain on board, even though on long flights there might be three or four pilots but only one CAPTAIN. He is responsible for the flight even if he is not piloting all the time. Loved stacey gordon's comment.
Wrong! There might be several captains in the cockpit, but only one commander, and he is in charge!
alex hidveghy 2
You’re missing the point completely and only reiterating what Tom said in the first place!

You can call them whatever you want, captain, commander, pilot in command, they all wear four stripes regardless and are captains.

Yes, only one is designated the ships commander or captain for that leg for legal terms.

Which is EXACTLY what Tom said!!

How is he wrong? Please explain in detail.
padrooga23 1
I think there is often confusion re: officer ranks. Air Force rank structure followed the Army's terminology from whence it came.
The captain of a naval ship is in command but their rank is higher than commander (depending on the size of the ship... ) The naval "Captain" rank is full bird or rather, the army/AF equiv of a colonel

Clear as mud, eh?

in order Air Force/Naval:

01-2nd Lt/Ensign
02-1st Lt/LT Junior GradeJG
04-Major/Lt Commander
05 Lt. Col/Commander
06 Colonel (full bird)/Captain
07-Brigadier General (1 star)/It gets confusing here...Vice Admiral lower half
08-Major General (2 star)/ Vice admiral upper half
09-Lt. General (3 star) /Vice admiral
10-General (4 star) /Admiral
alex hidveghy 2
And note, those ranks are slightly different overseas! Just ask the Royal Navy. I’ve seen ships commanders while being Lt. Cdr. that’s at least several strips BELOW the full four ringer....
alex hidveghy 1
Agreed! On both counts....
I still relieve myself in the head.
Bob Curry 4
If you really want to confuse the passenger sitting next to you, explain that when pilots talk about knots they are referring to their speed in nautical miles per hour, and that what they really mean is their indicated airspeed - the speed that they would be going if their airplane was at sea level on a standard day and measuring the same dynamic pressure.
jptq63 5
If the person survived this far, do you think you could explain "standard day"....
Jasper Buck 5
A standard day, also known as the ICAO Standard Atmosphere, ISA is a standard against which to compare the actual atmosphere at any point and time.

The ISA is based the following values of pressure, density, and temperature;

Sea level
Pressure of 1013.2 millibar (29.92 inches)
Temperature of +15 °C (+59 °F)
Density of 1,225 gm/m3

The standards used by the aviation industry for aircraft performance and operations. Which is why operations at Denver on a hot day require some due diligence as to available runway length and 2nd segment climb performance.

R Jolly 8
I don't know about the western world, but out here in India the pilot announcements are always in terms of ground speed (true air speed, corrected for wind speed) and not indicated air speed. That probably makes more sense to a layman in the cabin who can relate the distance remaining to destination with the approximate time it will take to complete the trip. And interestingly, the pilots generally announce the speed both in knots and kmph.
Very pragmatic and practical - thanks for posting.
alex hidveghy 1
Yes, because the average layman would have a fit if only they knew what it takes to become either an airplane or ships captain!

And how on earth can you fly or sail thousands of miles (nautical or otherwise!) across the globe and arrive at your planned destination on time without getting lost?!.....
alex hidveghy 1
Not only that, but the observant ones will also notice that your back of seat screen of the moving map will show all units in both English as well as metric! The only thing that remains consistent is time of flight, time remaining, time at origin and ETA at destination.

In LOCAL time, of course!!
womlliv 1
alex hidveghy 1
Sure, I could, but I’ll let Jasper below show you.....
alex hidveghy 1
Airspeed or Groundspeed? Both are in knots.....
Tim Dyck 2
I miss the old days when measurements were based on things like the Kings stride and his far a horse could pull a plow befor needing a rest. All these new tangled ideas are just too hard to grasp...
alex hidveghy 2
Hardly new, my friend! The knot as in nautical mile per hour has been around for a few centuries now.
Talking about horses, how about hands?
Tim Dyck 1
My post was in jest to point out how times and cultures have changed. Hands, inches, feet...etc were all based on dimensions if the human body. But since my hand is likely a different size then yours there needed to be a standard. Romans used the emperor, later fudal times would use the king but both of those systems fell apart when a ruler died and the new ruler had differant dimensions. Knots themselves came from knots in a rope tied to a log that was tossed out and then after a measured time the number of knots was used to estimate speed and then transferred to the map to estimated position. Times change and in the future they will continue to change and the knot might give way to something else.
alex hidveghy 2
Maybe, maybe not.

The knot has been around for the past 500 years or so? Slow moving, huh?

just like one nautical mile per hour!.....
rbt schaffer 2
I used to use MPH in my Champ to make it go faster and KTS in big airplanes just because..
David Hasse 2
That X gets less and less equal to Y as you approach the poles degree wise there's some geometry and algebra for coordinates to have relevance beyond the tropics. The great circle radial vector on a sphere relationship, glad for maps nanu nanu.
bobinson66 2
It would have been cool if they chose fathoms to measure altitude. According to wiki, fathoms have never been recognized as an International Standard unit. Debate rages (as if) as to whether a fathom was equal to the height of the average man or the length of a mans outstretched hands. Length varied as did the size of humans. People didn't have access to the nutrition we have today and thus they were smaller hundreds of years ago. Another possibility is to define a fathom as a thousandth of a nautical mile. Now we are getting somewhere.
alex hidveghy 2
I believe a fathom is approx. 6ft?
Try looking up furlong, too. What did you find?!
Another totally logical solution would be to adopt the metric system, which is consistent and widely understood world wide. I am not going to hold my breath for the outrage I anticipate at this suggestion. We already use metric temperature measurements with Celsius.
Jasper Buck 8
"We already use metric temperature measurements with Celsius."

U.S. pilots can request altimeter settings in millibars. ATC will report standard sea level pressure of 1013.2 millibars for example. Otherwise they would get the same report in inches (e.g. 29.92" Hg).

You'll be glad to know that the FAA did issue an Order (1020.1A TRANSITION TO THE METRIC SYSTEM) which set fort the policies, responsibilities, and guidance governing agency metric conversion activities. The order also implemented and transmitted Appendix 1, Order DOT 1020,IB, Department of Transportation Transition to Metric System. All this happened in December 1984. >;-) All of it met with a big yawn in my office.

To quote a number of very recent (2021) FAA documents "English dimensions will govern."

Well, there you go.


Capt J Buck
FAA (Ret.)
alex hidveghy 1
Yet ATIS - which all American pilots use- gives temperature in Celsius only, not Fahrenheit! How come?

Better get your formulae or conversion charts ready, Jasper!

Nothing to do with atmospheric pressure, millibars or inches of Hg!

I’ve noticed that in your comments you kind of disparage or defend the English system then give examples of conversions, almost negating what you stated defending. Strange.
Jasper Buck 1
"ATIS - which all American pilots use- gives temperature in Celsius only, not Fahrenheit! How come?"

The FAA standard is to use Celsius for temperature and knots for speed. Wind direction is always given in True. Reference:
FAA Order JO 7900.5, Surface Weather Observations
FAA Order JO 7210.3BB Facility Operations (ATIS Reports)

"Better get your formulae or conversion charts ready, Jasper!"

Thanks for the heads up. I think I already have (and have had for a long time) my conversion chart at the ready. It's in my electronic flight bag, in my Aeronautical Information Manual (AIM), Table 7−1−1 Weather Elements Conversion Tables. Reference: FAA Aeronautical Information Manual 13/30/2020 ed.

All the foregoing documents free from the FAA' website by the way.

I neither disparage or defend the "English system". Aeronautical and weather reporting standards, terminology and reporting are what they are. It is important that an aviator understand all of it and use the appropriate criteria in whatever airspace they're operating in.

alex hidveghy 1
Yes, all true!

But it doesn’t negate the fact that I first mentioned that ONLY Celsius is in the ATIS, not Fahrenheit!! That’s my only point.

The ATIS reports C, not F, and as you say, it is what it is, which is ICAO. Outside the US, they don’t need conversion tables or any of that other stuff since they are well versed in Celsius in their daily lives outside of aviation.

And it’s also the only reason you have those conversions you quoted! Thanks for confirming what I stated originally, I knew that all......and as an aviator, I can assure you I fully understand it. Like you, I used to be an instructor and taught the subjects in depth. In two different countries, to boot! Switching from one to the other with no problem.
Yeah - remember the Gimli Glider!
Tim Dyck 1
I watched that land on the race track. Pretty impressive flying skills by the crew.
alex hidveghy 1
But terrible math skills In not in knowing the mix up in units that led to a near disaster!
I bet their Chief Pilot had a few words with them when they eventually returned......
Tim Dyck 2
It was at a time when Canada was switching over to the metric system and Quebec as usual was not in sync with the rest of Canada having switched befor the other provinces. The Jet was fueled up in kilograms of fuel wile the Captain had done his calculations in pounds, thus they ran out of fuel just under half way through their trip.
alex hidveghy 2
Remember it well.
To this day, it’s used as an example of how things can go wrong in aviation, coupled with a “successful “ final outcome....
Peter Fuller 2
In the USA, complete adoption of the metric system is the future, and always will be.
paul trubits 2
If it wasn't for Ronald Regan we would be on the metric system. We did get two liter soda bottles though.
womlliv 1
Yes, common sense. Been trying since 1970s?
strickerje 1
We could, but it's also logical to keep the system we have since it's optimized specifically for aeronautical navigation.
jbermo 2
If truly a Metric world, then Meridian relationships of degrees of Longitude and Latitude must be changed - since all were English derived and all were related to the nautical mile.
And I assume time as well! 100 minutes per hour and 10 hours a day!
Peter Fuller 6
I had a summer job once where the punchcard time clock recorded 100ths of an hour rather than minutes, to make the paymaster’s job easier. If you punched in at 07:98 you were a little early!

This business of knots v statute miles v kilometers reminds me of the Air Canada 767 “Gimli Glider” incident in 1983, in which confusion over gallons-imperial gallons-liters-pounds-kilograms resulted in insufficient fuel being loaded, loss of both engines due to fuel exhaustion, and a dead-stick landing.
And also the loss of the Mars Climate Orbiter probe due to an error in acceleration data between the JPL navigation team, who used metric distance units, and the probe designers at Lockheed that used English distance units.
alex hidveghy 1
That’s why projects of this nature requires careful coordination and never assume!
Just imagine how the English Channel Tunnel would have gone had the French and English engineers on either side had not collaborated extensively! It would not have been joined in the middle! Expensive mistake.....
Edward Bardes 2
Imagine if the world had adopted a base 12 system when SI units were first conceived.
alex hidveghy 1
Uh, some countries already had a base 12 system for many decades (U.K.) using shillings, six pence, half a crown etc. way before they went decimal and SI (Systeme Internationale).

Believe it was around 1972 that they went decimal with the new penny....

That brought them in to line with most of the worlds decimal system, so SI came much later, not before.
womlliv 1
scondas 1
What exactly is ground speed in ADS-B? Where is the “ground”? I am guessing it is the speed over the WGS-84 ellipsoid. Does anyone know for sure?
Jasper Buck 2
See the following FAA guidance;

Advisory Circular AC No: 20-165
Date: 5/21/2010

Airworthiness Approval of Automatic Dependent Surveillance - Broadcast (ADS-B) Out Systems

Appendix 1. Message Elements Descriptions

1. Position. These parameters are derived from the position source and provide a geometric based position. Reference all geometric position elements broadcast from the ADS-B unit to the World Geodetic System 1984 (WGS-84) ellipsoid. Latitude and longitude is required to be transmitted by 14 CFR § 91.227.

Also see:


Geodetic Reference Datum 3.1

All published geographic coordinates indicating latitude and longitude are expressed in terms of the World Geodetic System − 1984 (WGS−84) geodetic reference datum


Capt. J Buck
alex hidveghy 1
In very simple terms, ground speed is your speed over the ground that you are traveling on. It matters not what units you actually use for the speed, it’s to differentiate between your airspeed, which is speed through the air, not over the ground! Again, units do t come in to play here. The only times these two are equal is when the winds are calm, no wind.

If you know anything about basic navigation (whether aerial or maritime) you would know about the triangle of velocities where one side is represented GROUNDSPEED and track (course for Americans), another is wind velocity (direction from and its speed) and the third side is true heading and true air speed (TAS). Each side is a vector in that it is made up of of two components, speed and a direction. Know any four (2 sides), you can always calculate the third side. Nautical navigation is similar.

Ask Capt. Buck for more details and the AC.......
Nautical miles still makes more sense than any imperial measurement. Feel sorry that the US is still 1 of the 3 countries using a system that makes no sense at all. Even the inventors of the system switched to Metric. My guess is that Von Braun did not use the Imperial system :)
ADXbear 1
Clear as
alex hidveghy 1
It is, if you have ever done either air or naval navigation basics! It’s a whole subject in itself.

Tons of books on it and every commercial pilot and ships captain has to have done a course in it at some stage during their careers.
J B 1
The headscratcher seems less the legacy NM / Knot use, but the article's reference to other data in competing measurement systems, all to be kept coherent (by the Autopilot, if not THE pilot, I guess.)
Peter Fuller 1

Link displays the International Civil Aviation Organization document “Units of Measurement to be Used in Air and Ground Operations”. Its specified standard units are all metric. Nautical miles, feet, and knots listed as “alternative units permitted for temporary use”, but no termination dates have yet been established for use of these.

Carefully meter any study of this dense and lengthy document lest you be tied up in knots.
tbscotty54 1
You have all made very easy easy!
Nautical miles make all the sense in the world, especially when you're flying in circles!
"Ship", or "airship", usta be the common vernacular thru WWII. "KIAS" vs "MPH", that's another story.
Jasper Buck 3
Airship is still in the FARs. Part 1 definition s "Airship means an engine-driven lighter-than-air aircraft that can be steered." and Part 61 pilot certification rules, etc.

I guess that would be the Goodyear blimp.

From what I've read airships are becoming popular again with several companies working on new designs. The FAA even has a relatively new webpage that talks about airships, airship regs and and how to get on certified:

alex hidveghy 2
And again, a term originally derived from sea-going vessels, ships!
Even the FAA uses the term as you have shown here. Blimp is the vernacular term and not universal.
padrooga23 1
Blimp I think refers to a lighter than air ship without a solid frame, that does not exist when not inflated, whereas a Dirigible, or Zeppelin has metal or rigid framework, throughout, that encompasses multiple inflatable compartments. Think Hindenburg.

I wonder if the word blimp, is play on the fact that it would B Limp, without the gas bags inflated.
the cool thing about having two (or more) measuring systems when piloting, is that the different systems force you to convert from one to the other, usual in your in your head...and in converting, you internalize it.
patrick baker 1
i have found it a silly affectation for nearly 50 years, this nautical mile, the so-many knots airspeed. What is the point? As a practical matter i interchange nautical with statute miles, much like many other pilots. One silly inconsistancy in a world full of them.
Jasper Buck 3
"As a practical matter i interchange nautical with statute miles"

That's OK but consider that the cloud clearance and flight visibility regulations (most notably 14 CFR 91.155 (Basic VFR weather minimums) are in statute miles and not nautical.

But, on the other hand the ATC transponder and altitude reporting equipment and use requirements FAR 91.215 (ATC transponder and altitude reporting equipment and use.) are all in Nautical miles. As are the Grand Canyon special flight rules SFAR 50-2 and the Special awareness training required for pilots flying under visual flight rules within a 60-nautical mile radius of the Washington, DC VOR/DME (FAR 91.161.) .

Be careful out there.


Capt J Buck
FAA Aviation Safety inspector (Ret.)
alex hidveghy 1
Don’t forget ICAO and International rules!
Only the US uses statute miles for that, the rest of the world does not!
Also, if you listen to ATIS anywhere in the world - including the US - temperature is always given in Celsius/Centigrade, not Fahrenheit.
patrick baker 1
look at the round guage airspeed indicator and see both knots and mph's. Why waste the small dab of paint that indicates knots. Doesn't much matter until speeds are bled off and flaps are deployed and power is reduced and a solid approach speed is dialed in. Then pick one and be sure not too much speed is taken off, and go and make a good landing. 15% difference is of some importance.....
Jasper Buck 2
"look at the round gauge airspeed indicator and see both knots and mph's"

Very few of those airspeed indicators around nowadays. Mostly old ASIs from years ago in older Cessnas and Pipers. Maybe a Beech or two. FARS 23 and 25 now refer to Knots. Most ASIs are in Knots with no inner band with mph. I switched the ASI in my Cessna 182 to a knots only gauge long ago. There are number of repair stations that will rescreen the face of the gauge to get rid of the mph. The FAA/ATC/ICAO wants you to think knots. When ATC comes on he Air and asks you to slow to 200 or maintain 180 to the outer marker he means knots. Etc.

alex hidveghy 0
Because most, if not all, aeronautical terms come from the days of maritime navigation and shipping. Hence, a nautical mile. The clue is in the name....
You also have Captain, First Officer, bulkhead, port, starboard, course, charts etc all of which originally came from the maritime world.
And, of course, before the heyday of jet transport, we had flying boats like the Pan Am Clippers or the early days of Imperial Airways, now better known as British Airways.....
Jasper Buck 5
"...most, if not all, aeronautical terms come from the days of maritime navigation "

Don't think so. Very very little aeronautical terms and terminology come from the maritime community. As an example the aviation industry does not use terms like flotsam and jetsom, port and starboard, bridge and keel, cans or nuns, freeboard and adrift, away and awash, on and on.

Please read:

History and Etymology for the word Nautical
Latin nauticus, from Greek nautikos, from nautēs sailor, from naus ship or pertaining to sailors, seamanship, or navigation; maritime.

History and Etymology for the word not
Old English cnotta "intertwining of ropes, cords, etc.," from Proto-Germanic *knuttan- (source also of Low German knütte, Old Frisian knotta "knot," Dutch knot, Old High German knoto, German Knoten, perhaps also Old Norse knutr "knot, knob") is the the nautical unit of measure of speed (1630s) is from the practice of attaching knotted string to the log line at equal distances The ship's speed can be measured by the number of knots that play out while the sand glass is running. The term Knot is a unit of speed equivalent to 1 nautical mile (1.8520 km; 1.1508 mi) per hour. Originally the speed of a moving vessel was measured by paying out a line from the stern; the line was tied into a knot every 47 feet 3 inches (14.40 m), and the number of knots paid out in 30 seconds gave the speed through the water in nautical miles per hour.

Until the mid-19th century, vessel speed at sea was measured using a chip log. This consisted of a wooden panel, attached by line to a reel, and weighted on one edge to float perpendicularly to the water surface and thus present substantial resistance to the water moving around it. The chip log was cast over the stern of the moving vessel and the line allowed to pay out. Knots tied at a distance of 47 feet 3 inches (14.4018 m) from each other, passed through a sailor's fingers, while another sailor used a 30-second sand-glass (28-second sand-glass is the currently 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 gave 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%

The distance between the knots on the log-line should contain 1/120 of a mile, supposing the glass to run exactly half a minute. [Jorge Juan and Antonio de Ulloa, "A Voyage to South America" 1760]
Hence the word knot came also to be used as the equivalent of a nautical mile (in pre-World War II use in U.S. and Britain, about 6,080 feet). A speed of 10 knots will cover ten nautical miles in an hour (equivalent to a land speed of about 11.5 mph).

First Known Use of Nautical 1552
First known use of Knot 1610

For your education I refer you to:

1. 2019 American Practical Navigator 'BOWDITCH' Vol 1 & 2 (1203 pp.)
The American Practical Navigator (colloquially often referred to as Bowditch), was first published in 1802. The work was originally written by Nathaniel Bowditch, and is an encyclopedia of navigation. It serves as a valuable handbook on oceanography and meteorology, and contains useful tables and a maritime glossary.

2. Dutton's Nautical Navigation 15th Ed. Naval Institute Press; December 7, 2003
The art and science of nautical navigation that both amateur and veteran navigators can use to safely navigate the waters of the world. First published in 1926 by Cdr. Benjamin Dutton a USN Captain.

3. FAA Instrument Flying Handbook FAA-H-8083-15B
The Instrument Flying Handbook is designed for use by instrument flight instructors and pilots preparing for instrument rating tests. Instructors may find this handbook a valuable training aid as it ncludes basic reference material for knowledge testing and instrument flight training. Other Federal Aviation Administration (FAA) publications should be consulted for more detailed information on related topics.
Free from

4. FAA Instrument Procedures Handbook FAA-H-8083-16B
The discussion and explanations reflect the most commonly used instrument procedures. Occasionally, the word
“must” or similar language is used where the desired action is deemed critical. The use of such language is not intended
to add to, interpret, or relieve pilots of their responsibility imposed by Title 14 of the Code of Federal Regulations (14 CFR).
Free from

5. 14 CFR 1 Definitions and Abbreviations
Free from

Tim Dyck 2
Thanks for the article. For the most part it is correct except it says the first use if the term knot was 1610 yet Columbas used it in his writings over a century befor that. Perhaps the article you used had made a simple mistake somewere because otherwise it seems to discribe the process of measuring speed the same as old navel literature.. I don't know when this method was first used but it has been around a long time and it amazes me how how accurate marine navigation was wile using such primitively methods.
alex hidveghy 1
Sorry, I disagree!

You even referenced many naval and nautical terms in your discussion here. If it was not relevant or related, why did you use them as examples? I agree with where the term knot came from, however. But I was very puzzled by the rest of your comments since it is well known that ships used the term knots well before the Wright brothers! Cabins are used onboard many ships, naval as well as civilian. Immigration and landing rights paperwork on board aircraft on international routings all have the world vessel traveled on. Quaint term for an aircraft but is more usually applied to sea-going vessels, I.e, ships and boats.

And for good measure, where I come from, you do actually use the terms port and starboard on aircraft which of course, are nautical terms for left side and right side! The nav lights for same is colored red and green which is exactly the same as for ships and boats. And the latter are definitely nautical vessels.

Sounds like your experience is solely related to the US, not global operations.

Furthermore, ships have been around this earth a lot longer than airplanes!

Also, as a former naval officer and airline pilot, I believe my information is sound. As is my history.
Jasper Buck 1
"You even referenced many naval and nautical terms in your discussion here."

Other than knots and nautical (as in speed and miles) I don't think I've referenced many "naval and nautical" terms. Please point hem out if I have and I'll correct myself.
Peter Koranyi 1
I see the many nautical terms used in and around aircraft. Then I wonder why air traffic controllers issue directions to turn left or turn right. Pilots learn and use a lot of specialized terminology, why not use port and starboard as well? Any historical perspectives out there?
Jasper Buck 2
"...why air traffic controllers issue directions to turn left or turn right."

The use of the words "left" and "right" (e.g. "Procedure turn, holding pattern entry, traffic pattern entry) are used by ICAO and are designated “left” or “right” according to the direction of the initial turn." E.g. "enter right traffic" or "enter a left holding pattern.

This standard is described in:
ICAO Document 8168 The Procedures for Air Navigation Services — Aircraft Operations (PANS-OPS) Volume I — Flight Procedures. And the FAA's Air Traffic Controllers instructions FAA Order 7110.65.
alex hidveghy 1
Why? Because it’s dated terminology!

And it’s much easier and quicker in today’s world to say, turn left 10 degrees or right to intercept the BLD 050 radial than it is to use starboard or port. Usage has declined over the past 70 years. it’s called progress......
alex hidveghy 1
OK, not all or even most. But definitely quite a few, as has already been indicated and by others.

Read the first paragraph of this article. The one that says aerial navigation has adopted the ways of its marine counterpart......

Nautical navigation came way before aerial nav, and that’s the reason where some aeronautical terms originate.

In some countries and in previous decades, the terms port and starboard were used frequently to describe left and right sides. Gradually, they fell out of usage for airplanes but came from ships and maritime navigation. So, while the terms themselves are no longer used universally, the nav lights on any aircraft remain red for port and green for starboard. In fact, I recall an aide memoire to help remember which was which. The drink port is dark red in color, so the port (left) light is the red one, therefore the other has to be green. I should add when viewed from the front, not rear.......
Early blue-water flights use astronavigation (sextant and chronometer and paper tables). 1 arc minute latitude is 1nm (on a spherical earth)- so one less conversion. Also needs one less scale on paper charts (use the nearest vertical latitude line with your dividers)

Now - is this still need ? BUT - MARS Climate Orbiter was lost to mixed units, Gimli Glider was mixed units - during a changeover to km/h (or m/s?) I'm pretty certain accidents would happen. Under stress you remember first training - first flaps at 180 knots would be bad delayed until 100 knots (180 km/h)...

WE have computers to convert wherever needed - why risk the change-over?


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