AC320
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Converting From Mi/Km Into Kts?

Mon Mar 26, 2001 1:17 am

I was looking at the Boeing and Airbus sites where they give all the speeds for their aircraft in either miles or Kilometres per hour, so how do I convert both into nautical miles per hour (kts)?
fuddle duddle
 
OPNLguy
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RE: Converting From Mi/Km Into Kts?

Mon Mar 26, 2001 1:44 am

According to my workstation, one (statute) MPH equals=

.8689909 knots

1.609258 kilometer/hr
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
chdmcmanus
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RE: Converting From Mi/Km Into Kts?

Mon Mar 26, 2001 2:13 am

OPNLguy is right,

NM=SM / 1.152

NM=KM / 1.855
"Never trust a clean Crew Chief"
 
AC320
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RE: Converting From Mi/Km Into Kts?

Mon Mar 26, 2001 3:54 am

Thanks guys.

I've been working on the schedules for a VA and this will really help get my job done faster!
fuddle duddle
 
OPNLguy
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RE: Converting From Mi/Km Into Kts?

Mon Mar 26, 2001 4:37 am

>>>I've been working on the schedules for a VA and this will really help get my job done faster!

Pardon me if you already knew/considered this, but if you're using speeds from the manufacturer's websites, keep in mind that they are generalized, and essentially a zero-wind speed. For accurate schedule planning, you'll need to consider a certain amount of head/tail wind, as it will affect the enroute time, especially on longer flight segments.

As a general example, take a 737-700 on a 1,500nm flight. The aircraft's true airspeed (TAS) at FL350 is about 450 knots, but that's zero-wind. Traveling westbound into an assumed 100-knot headwind, the aircraft still has a 450 TAS, but is now at a GROUNDspeed (GS) of 350 knots. Conversely, an easbound flight with an assumed 100-knot tailwind would produce a 550-knot groundspeed. (I say again, this is a generalized example, and doesn't consider the climb/descent).

1000nm distance divided by 350-knot GS = 2:51
1000nm distance divided by 450-knot GS = 2:13 1000nm distance divided by 550-knot GS = 1:49

One certainly can't consider *every* wind variable when planning schedules, but it'd prudent to consider at least *some*, or your VA could find itself behind schedule...

Cheers...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
AC320
Topic Author
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RE: Converting From Mi/Km Into Kts?

Mon Mar 26, 2001 11:30 am

Way ahead of you, we already stick in some extra time to the scheduled time to account for ATC, ground delays, accidents, and weather. But thanks for the tip anyway..  Smile
fuddle duddle
 
timz
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RE: Converting From Mi/Km Into Kts?

Tue Mar 27, 2001 5:25 am

statute mile = 1.609344 km exactly

(in other words, 63360 inches per mile, and the inch is defined as 0.0254 meters exactly)

nautical mile = 1852 meters exactly

Since the earth isn't spherical the definition of a nautical mile isn't obvious, and there have been various ones in the past; the 1852-meter definition is presumably semi-arbitrary.

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