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#101
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Absolute lowest altitude you can fly (legally)
Stefan writes:
And what exactly in this reglementation is not ICAO conform? I don't know; that wasn't the question. The question was whether or not the French still use metres in aviation, and they obviously do, because it's right in the regulations. -- Transpose mxsmanic and gmail to reach me by e-mail. |
#102
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Absolute lowest altitude you can fly (legally)
Mxsmanic,
I know, in Germany everything is prohibited, except that which is allowed. More areas of life you have no clue about but still show arrogance toward. Sad. Very interesting how you resort to personal attacks more and more. -- Thomas Borchert (EDDH) |
#103
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Absolute lowest altitude you can fly (legally)
Mxsmanic wrote:
writes: Knots are not dimensionless in aviation. A knot is one nautical mile per hour, and that nautical mile is the distance corresponding to one minute of latitude at the equator. Yes, but that is largely incidental today, particularly for east-west movements away from the equator. Anyone using that relationship for dead reckoning, for example, can get into trouble if he's not very careful. No, it's not incidental today. Back in my dead-reckoning days in the Air Force we used Lambert Comformal charts, which uses a conical projection. Using 1nm for dead-reckoning going east-west (across longitude) was plenty accurate, until you got into the extreme northern latitudes (which is where grid navigation came into play). But even there, distance across longitude isn't necessarily the problem; heading is. And, look at a U.S. sectional chart. It uses Lambert Conformal conic projection, and using 1nm for dead reckoning east-west (longitude) is plenty accurate. You won't get into trouble. Now, let's say you plan a flight across the U.S. from New York City to Los Angeles. You'll be using (guessing here) maybe seven or eight different sectional charts. Each has a different conical projection point. So, even if, on the chart, you are plotting your route in a "straight" line, you are really approximating a Great Circle route, and your no-wind heading (true or magnetic, makes no difference) will be up to several degrees different when you arrive in Los Angeles (compared to your departure heading in New York). Obviously, I'm ignoring magnetic variation here. This is REALLY apparent when flying from, say, San Francisco to Tokyo. But, this is not a big deal, since you'll be using waypoints along the way, and the heading between waypoints won't change enough to be a worry. But, you'll probably notice that your true heading changes by a degree or so from one waypoint to another. This applies to ONC and JNC charts too, and it worked fine for our overwater navigation in KC-135's. So, for dead reckoning today it's not incidental at all. Of course, if you use a GPS or FMS as your primary navigation source it is, since the map projections are taken care of by the computer in your box. Anyone using lat/long and some spherical trig (like the old guys who crossed oceans used sextants to determine their position) will make use of these things. I don't think too many pilots use sextants today. I think an increasing number of pilots don't know how to do anything except look at a moving map display, or set an autopilot. The lazy ones among us (or like me, the ones really poor at math) will use GPS, which does the same thing. Yes. But what you don't use, you lose. And I don't think pilots are taught how to use sextants, anyway. Although I've heard that early airline navigators and pilots used them--which is why some older aircraft have little windows above the pilots, for shooting the stars. sigh 35 years ago I could whip up a comp for a celestial shot in less than a minute. Today it would probably take me a week. Of course, we used an Air Almanac and an H.O. 249 to take care of the pesky trig stuff, so it was mainly adding and subtracting stuff involving the GHA of Aries. :) ANYWAY, if you're serious about plotting your course on a chart, know what map projection you're using and the distance between waypoints. Using a conical projection chart and a standard plotter will be plenty accurate for any kind of dead-reckoning, no matter which direction you're going. Now, flying an ARA into Thule, Greenland is a whole different animal. :) --Walt (who is probably showing his age) |
#104
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Absolute lowest altitude you can fly (legally)
Wolfgang Schwanke wrote: It's really the Americans who do something different, and used their power to force their ways on the rest of the world. Surely metric is preferrable all other things being equal. It's not a big issue in practice, but statments like the above are tinted by national prejudice and should not be tolerated. Regards -- __o http://www.wschwanke.de/ _'\,_ C'est le tour de France! (_)/ (_) Hey, c'mon, that foot-and-pound system was forced on us by the British. It's all their fault! IIRC, there was a big push in the '70's or '80's in the U.S. to start moving to the metric system, since it really is more logical. But, there was a big push back from the general American public who liked their feet and had no desire to transform them into meters. :) As was mentioned previously by That Poster We Will Not Name, the unit of measurement in aviation doesn't really matter all that much. FL350 could be 35,000 feet or meters, but as long as everyone uses the same unit of measurement it doesn't really make any difference. Now, when I flew a gunship (AC119K) in SE Asia, we used klicks and meters as our unit of measurement (for firing solutions at least). I guess I could use this as evidence of an insidious attempt by Europeans, backed by the U.N., to force a unit of measurement on the American people they don't really want. A guerrilla war type of thing. But, I won't, because it's stupid. To wrap this up, I'll just say one thing: a football field should ALWAYS be 100 YARDS long. Comments? :) --Walt (with tongue firmly in cheek) |
#105
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Absolute lowest altitude you can fly (legally)
Walt schrieb:
Hey, c'mon, that foot-and-pound system was forced on us by the British. It's all their fault! Yeah, but at least, they have reasonable gallons. IIRC, there was a big push in the '70's or '80's in the U.S. to start moving to the metric system, since it really is more logical. But, there was a big push back from the general American public who liked their feet and had no desire to transform them into meters. :) The irony is that the metric system was forced some 200 years ago to the unwilling European public by argument of sheer force. Stefan |
#106
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Absolute lowest altitude you can fly (legally)
Neil Gould wrote: Recently, Walt posted: To wrap this up, I'll just say one thing: a football field should ALWAYS be 100 YARDS long. Comments? I guess that depends on what you mean by "football field". |-0 Neil My point exactly. :) --Walt |
#107
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Absolute lowest altitude you can fly (legally)
Walt writes:
But, this is not a big deal, since you'll be using waypoints along the way, and the heading between waypoints won't change enough to be a worry. But, you'll probably notice that your true heading changes by a degree or so from one waypoint to another. This is an interesting point. I do see the heading towards a waypoint change slowly over time, and I've naturally assumed that it was just the wind. However, if the distance between waypoints is quite long, I can see that the actual track to follow could change over time due to the great-circle character of the track between the waypoints. Unfortunately, I don't remember offhand how long the distance would have to be before it would change by a degree or more at intermediate latitudes. Of course, if the waypoints were on the Equator or exactly north-south, there would be no change in heading. So, for dead reckoning today it's not incidental at all. Yes, _if_ someone is navigating by dead reckoning. My point was that hardly anyone uses dead reckoning by hand these days. And as one increases in latitude, the 1 degree = 1 minute relationship gets more and more iffy, too. 35 years ago I could whip up a comp for a celestial shot in less than a minute. Today it would probably take me a week. Of course, we used an Air Almanac and an H.O. 249 to take care of the pesky trig stuff, so it was mainly adding and subtracting stuff involving the GHA of Aries. :) I'm sure most other pilots have the same problem--if they ever knew how to do this in the first place, that is. ANYWAY, if you're serious about plotting your course on a chart, know what map projection you're using and the distance between waypoints. Using a conical projection chart and a standard plotter will be plenty accurate for any kind of dead-reckoning, no matter which direction you're going. Not very practical for me these days. --Walt (who is probably showing his age) When you flew, the B-52 was an important part of the military's aircraft inventory. Whereas today, the B-52 is an important part of the military's aircraft inventory. -- Transpose mxsmanic and gmail to reach me by e-mail. |
#108
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Absolute lowest altitude you can fly (legally)
Walt writes:
Now, when I flew a gunship (AC119K) in SE Asia, we used klicks and meters as our unit of measurement (for firing solutions at least). What is a klick? -- Transpose mxsmanic and gmail to reach me by e-mail. |
#109
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Absolute lowest altitude you can fly (legally)
Mxsmanic,
What is a klick? One kilometer. 1000 meters. One of those ridiculous French things... -- Thomas Borchert (EDDH) |
#110
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Absolute lowest altitude you can fly (legally)
Recently, Walt posted:
To wrap this up, I'll just say one thing: a football field should ALWAYS be 100 YARDS long. Comments? I guess that depends on what you mean by "football field". |-0 Neil |
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