Knots -v- MPH

How do you describe your speed when flying?

  • I use knots why flying.

    Votes: 69 79.3%

  • I use MPH when flying

    Votes: 17 19.5%

  • I use kilometers per hour

    Votes: 1 1.1%
  • Total voters
    87
MPH.

My ASI was installed in 1940, when they used a real measuring system, and not some phoney-baloney Latin thing invented by French guys with too much time on thier hands....
 
Kilometers per hour?????
If God wanted us to use the metric system, he would have given us 10 fingers.
 
I trained in aircraft built in 1978, and I own an aircraft built in 1978, so it is knots for me. MPH just seems archaic and "wrong" for aviation.
 
MPH, Both of my planes; 1936, and 1939 use mph. I'm not as old as them but grew up using mph too. Knots are for ropes and boats:D
 
Lat/lon on the charts make it easy to use knots.
 
Mostly knots - for figuring things in cruise.
But, my ASI's primary scale is mph - so, mph for v speeds, climbs, approaches, and such.
 
I use MPH simply because the 1963 C-172 I fly has MPH calibrated ASI. When I flew newer planes I used Knots.
 
MPH for me............... I am toooo old to convert to knots and that pesky metric system..... :mad2::wink2:

Ben.
 
MPH for me since that's the predominant marking on my airspeed indicator and what the references are in the POH. It is also easier to speak MPH to young eagles I'm flying since they can relate to it.
 
I use whatever the airplane is equipped with.
 
Knots, since 1nm=1' latitude, it just makes all the calculations cleaner.
 
Knots, and the dual MPH/KTS ASI in the Arrow I fly drives me up the freakin' wall.
 
Whichever one is on the airspeed indicator.

And to this day I obey my physics professor's first rule of solving equations: Don't mix units. (If you have more than one set of units, convert them all to the primary units you will be working with)
 
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Cap'n Jack said:
Lat/lon on the charts make it easy to use knots.
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^ What he said.

I know we don't use this in our everyday flying, but the way that knots, nautical miles and the lat/lon system interface is amazing.

I had it all explained to me a few years ago by an old man who was a NASA ballistics expert in the 70's and now circumnavigates by himself on his 30 foot sloop using celestial navigation and dead reckoning.
 
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dell30rb said:
^ What he said.

I know we don't use this in our everyday flying, but the way that knots, nautical miles and the lat/lon system interface is amazing.
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Maybe because it was designed that way?
 
knots is nautical miles per hour... all your charts are in nautical miles so that makes time/distance calculations easier
 
dell30rb said:
all your charts are in nautical miles so that makes time/distance calculations easier
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Correct in theory but wrong in practical application.

A chart is just piece of paper drawn to a scale of no particular units. (It is scaled in parsecs or thousandths of an inch just as much as it is in nautical miles) The plotter that is used for the actual measuring has both nautical and statute on it so chose the most appropriate units.

Never mix units. Pick the primary units that is obvious. (The airspeed indicator is a good one since it's right there in front of you on the panel) If the airspeed is in statute, measure with statute. If the airspeed is in knots, measure in knots. If it's gallons per hour, don't use liters per hour. If angles are measured in degrees, don't use radians. If you mix units, speed or otherwise, just ask the Gimli Glider pilots what can happen to you.
 
dell30rb said:
This is the best answer
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Not really, the ASI isn't all that bloody critical to flying that it be calibrated to any particular speed. As far as the flying part goes it could just as easily be marked with V speeds: Vso, Vx, Vy, L/Dmax, Va, Cruise, Vno, Max Cruise, Vne.

Where it makes a difference is in navigation and your airspeed isn't particularly useful in those regards where as ground speed measured in knots gives you slight advantage over statute mile or kilometer measurements
 
fgcason said:
Correct in theory but wrong in practical application.

A chart is just piece of paper drawn to a scale of no particular units. (It is scaled in parsecs or thousandths of an inch just as much as it is in nautical miles) The plotter that is used for the actual measuring has both naut*ical and statute on it so chose the most appropriate units.

Never mix units. Pick the primary units that is obvious. (The airspeed indicator is a good one since it's right there in front of you on the panel) If the airspeed is in statute, measure with statute. If the airspeed is in knots, measure in knots. If it's gallons per hour, don't use liters per hour. If angles are measured in degrees, don't use radians. If you mix units, speed or otherwise, just ask the Gimli Glider pilots what can happen to you.
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To make it practical, the Sectional Chart is marked off in 30' blocks of latitude which correspond to 30 NM. Since a C-152 cruises at 90 kts & 6 gph, if I take my pinky and fore finger and span them along a line of longitude to measure between two lines of latitude, I am simultaneously measuring 20 minutes of flight time as well as 2 gallons of gasoline along with 30nm. So you see, charts ARE marked in Nautical Miles.
 
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fgcason said:
Correct in theory but wrong in practical application.

A chart is just piece of paper drawn to a scale of no particular units.
Click to expand...


That's true, however if you are using airways... flying an instrument approach.. all of those distances and information are provided in nautical miles
 
fgcason said:
Correct in theory but wrong in practical application.

A chart is just piece of paper drawn to a scale of no particular units. (It is scaled in parsecs or thousandths of an inch just as much as it is in nautical miles) The plotter that is used for the actual measuring has both nautical and statute on it so chose the most appropriate units.

Never mix units. Pick the primary units that is obvious. (The airspeed indicator is a good one since it's right there in front of you on the panel) If the airspeed is in statute, measure with statute. If the airspeed is in knots, measure in knots.
Click to expand...

Regardless what is used on your ASI, you'll have to use knots and nautical miles when dealing with ATC.
 
fgcason said:
A chart is just piece of paper drawn to a scale of no particular units. (It is scaled in parsecs or thousandths of an inch just as much as it is in nautical miles) The plotter that is used for the actual measuring has both nautical and statute on it so chose the most appropriate units.
Click to expand...
When you find an IFR chart plotter with statute miles on it, let us know. In addition, your IFR flight plan must give TAS in knots, and when ATC asks your speed or tells you to fly a speed, that's in knots, too. So, VFR on your own, if you want to do it all in mph/statute miles, you can, but once you get into "the system," you'd better be working in knots.

And yes, I know that in the high altitude structure, sometimes speed is handled as Mach, but that's a different story.
 
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