2G
April 17th 20, 04:04 AM
On Tuesday, March 6, 2001 at 4:34:39 AM UTC-8, Jean Richard wrote:
> Kirk Stant a écrit :
>
> > Why? While I may agree that metric units are OK for ground use, in the air
> > and on the sea the Nautical mile (one minute of latitude) is the preferred
> > unit of distance, easily measured on any chart, and is likely to remain so
> > for the foreseeable future. Therefore, the Knot is the most useful unit of
> > speed. As far as altitude, feet are just as useful as meters, why change?
>
> I've been flying in Europe a few times and really appreciate to have
> altimeter in metre and not in feet since it's a lot easier to make
> glide calculations.
>
> I would like to get rid of our feet calibrated altimeter (I'm living
> and usually flying in North America...).
>
> As so far distance is concerned on a chart, we always use metres, and
> it's also a lot easier since you just take any rule to mesure distance
> and convert it from centimetres to kilometres.
>
> > For soaring, using Knots for airspeed and climb is nicely consistent and
> > makes for easy guesstimating of instantaneous glide angle.
>
> No ! Because your airspeed is not indicating ground speed, but airspeed.
>
> Here, we are sometimes happy to have GPS since they all work in SI.
>
> > And since a
> > nautical mile is just over 6000' (6080'), one can easily use multiples of
> > nautical miles per 1000' for mental figuring glide distances: 36/1 is 6
> > nm/1000', 30/1 is 5 nm/1000', 24/1 is 4 nm/1000', and so on. Try doing
> > any of that with Kph, Meters, and M/Sec!
>
> Distance in km and altitude in metres. That's all we need. Airspeed and
> vario are not used for gliding calculation, just for speed to fly -
> the Mac Cready (or any more sophisticated device) do the job for you.
>
> > I'm not a Europhobe
>
> SI units is not only for Europe. It's the official unit system in all
> America, except USA.
>
> > (I'm half French, and have lived in Europe many years)
> > but I do think that, for aviation at least, the archaic foot, nautical mile,
> > and Knot should remain in place indefinitely.
>
> At first, ICAO want to discard anything except SI. But due to difficulties
> in conversion (and cost), ICAO went for a « temporary » exception chart to
> included some non SI units. The MPH are no more accepted (here in Canada,
> selling a new airplane with MPH airspeed indicator is not legal).
>
> > Now if we could only get US
> > soaring pilots to stop using MPH and statute miles for speeds and distances,
> > instead of the Knots and NM they use in-flight, we would be getting
> > somewhere!
>
> SI is easier... Weather observation (METAR) in USA are mixing knots (wind)
> with statute miles (visibility), and feet (I don't know if Imperial feet
> and US feet are the same), inches of mercury. What a mess !
>
> > It's bad enough having to figure if you have enough NM to make
> > your 500K flight, but then you have to convert that into Statute miles for
> > club bragging rights!
>
> FAI distance badges are in kilometres, nothing else ;-))
>
> > Vive les pieds! A bas les Metres (une vrai connerie!)
>
> J'ai toujours préféré les maîtres aux pieds ;-))))
>
> Jean
International aviation standards use feet and English. All of my charts reference altitude in feet, as well as FARs. Can't speak for your European charts, however. The FAA will not be receptive to you busting airspace because your altimeter is in meters.
I have very rarely found it necessary to compute a glide angle while flying.. I always used X NM per thousand feet (X is directly related to achieved glide angle; I use 7 NM for may ASH31, which 73% of best L/D). And I still double-check my LX9000 using this same method. I just see how much distance closer I am at each 1000 ft mark. I get an instantaneous glide angle from my LX9000, but this varies so much that it is not of much value.
Tom
> Kirk Stant a écrit :
>
> > Why? While I may agree that metric units are OK for ground use, in the air
> > and on the sea the Nautical mile (one minute of latitude) is the preferred
> > unit of distance, easily measured on any chart, and is likely to remain so
> > for the foreseeable future. Therefore, the Knot is the most useful unit of
> > speed. As far as altitude, feet are just as useful as meters, why change?
>
> I've been flying in Europe a few times and really appreciate to have
> altimeter in metre and not in feet since it's a lot easier to make
> glide calculations.
>
> I would like to get rid of our feet calibrated altimeter (I'm living
> and usually flying in North America...).
>
> As so far distance is concerned on a chart, we always use metres, and
> it's also a lot easier since you just take any rule to mesure distance
> and convert it from centimetres to kilometres.
>
> > For soaring, using Knots for airspeed and climb is nicely consistent and
> > makes for easy guesstimating of instantaneous glide angle.
>
> No ! Because your airspeed is not indicating ground speed, but airspeed.
>
> Here, we are sometimes happy to have GPS since they all work in SI.
>
> > And since a
> > nautical mile is just over 6000' (6080'), one can easily use multiples of
> > nautical miles per 1000' for mental figuring glide distances: 36/1 is 6
> > nm/1000', 30/1 is 5 nm/1000', 24/1 is 4 nm/1000', and so on. Try doing
> > any of that with Kph, Meters, and M/Sec!
>
> Distance in km and altitude in metres. That's all we need. Airspeed and
> vario are not used for gliding calculation, just for speed to fly -
> the Mac Cready (or any more sophisticated device) do the job for you.
>
> > I'm not a Europhobe
>
> SI units is not only for Europe. It's the official unit system in all
> America, except USA.
>
> > (I'm half French, and have lived in Europe many years)
> > but I do think that, for aviation at least, the archaic foot, nautical mile,
> > and Knot should remain in place indefinitely.
>
> At first, ICAO want to discard anything except SI. But due to difficulties
> in conversion (and cost), ICAO went for a « temporary » exception chart to
> included some non SI units. The MPH are no more accepted (here in Canada,
> selling a new airplane with MPH airspeed indicator is not legal).
>
> > Now if we could only get US
> > soaring pilots to stop using MPH and statute miles for speeds and distances,
> > instead of the Knots and NM they use in-flight, we would be getting
> > somewhere!
>
> SI is easier... Weather observation (METAR) in USA are mixing knots (wind)
> with statute miles (visibility), and feet (I don't know if Imperial feet
> and US feet are the same), inches of mercury. What a mess !
>
> > It's bad enough having to figure if you have enough NM to make
> > your 500K flight, but then you have to convert that into Statute miles for
> > club bragging rights!
>
> FAI distance badges are in kilometres, nothing else ;-))
>
> > Vive les pieds! A bas les Metres (une vrai connerie!)
>
> J'ai toujours préféré les maîtres aux pieds ;-))))
>
> Jean
International aviation standards use feet and English. All of my charts reference altitude in feet, as well as FARs. Can't speak for your European charts, however. The FAA will not be receptive to you busting airspace because your altimeter is in meters.
I have very rarely found it necessary to compute a glide angle while flying.. I always used X NM per thousand feet (X is directly related to achieved glide angle; I use 7 NM for may ASH31, which 73% of best L/D). And I still double-check my LX9000 using this same method. I just see how much distance closer I am at each 1000 ft mark. I get an instantaneous glide angle from my LX9000, but this varies so much that it is not of much value.
Tom