Absolute lowest altitude you can fly (legally)

Watson writes:

If I recall correctly, 1 min of latitude = 1 NM everywhere (not just the
equator), aren't lines of latitude also called parallels and thus maintain
there equidistant relationship all the way to the poles?

The size of one minute of longitude contracts along each of the
latitude parallels as they get closer to the poles. At the equator,
one minute is one nautical mile (roughly); at the poles, one minute is
zero distance. At U.S. latitudes, one minute of longitude is
considerably smaller than a nautical mile--you can see this if you
look at sectionals.

And don't lines of longitude meet at the poles and therefore their angles
maintian the same
angular relationship yet the distances decrease the further one travels from
the equator?

Right--so one minute in an east-west direction gets smaller and
smaller as you move towards the poles. It's only one nautical mile at
the equator.

--
Transpose mxsmanic and gmail to reach me by e-mail.

On Sat, 06 Jan 2007 03:22:42 -0500, Roger
wrote:

The quickest and easiest answer is:

You learn to ignore it or go insane.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

That bad, huh? I'll retract my question/suggestion. It was intended
as a question. Seemed logical.

It is better for some to ignore it, but it won't always be ignored,
nor should it. Moderation organizes the effort into some sort of
authority. Independent (if not libertarian), aviators reflexively
kick back at any authoritarian figure, who tend to 'prove' themselves
by taking more authority.

But if I'm going to spend so much time and money in the air, then you
can be sure I want ordered skies, and to be with those accustomed to
discipline, and not 'free flight'. And think its better to argue with
authority than the uncivilized; though neither argue well. But it's
better to take chances with the former than the latter -- unless the
former is the one organizing the current disturbance. It's
stubbornness suggests as much.
--
Mike

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. 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. The lazy ones
among us (or like me, the ones really poor at math) will use GPS, which
does the same thing.


Dan


One minute of Latitude is 1nm, whether at the equator or just shy of the
pole.. it does not change

As for sextants.. I must be an old guy then.. as I have crossed the oceans
of air, relying on the celestial realm, my trusty sextant, a good watch and
lots of math.

BT

Walt.. you are singing my tune..

I remember Grid Celestial Navigation and those trusty HO249s..
Been a long time since I've looked at an Air Almanac

BT

"Walt" wrote in message
oups.com...

Mxsmanic wrote:
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.

That's the whole reason for waypoints. We live on a sphere but
dead-reckon on a flat surface.

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.

Your original statement was about dead reckoning. That was what I was
responding to.

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.

Just a teary-eyed remembrance from an old fart. I didn't expect much of
a response.


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.

That wasn't my point. I thought you were interested in navigation. Try
reading Dava Sobel's _Longitude_. Fascinating read if you're really
interested in navigation, whether 300 years ago or present time.

--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.


Nice putdown.

I gave you some tantalizing clues about navigation. Pursue them or
ignore them. Up to you.

--Walt

BT writes:

As for sextants.. I must be an old guy then.. as I have crossed the oceans
of air, relying on the celestial realm, my trusty sextant, a good watch and
lots of math.

Have you ever flung your eager craft through footless halls of air?

--
Transpose mxsmanic and gmail to reach me by e-mail.

Mxsmanic wrote:
Walt writes:


That wasn't my point. I thought you were interested in navigation. Try
reading Dava Sobel's _Longitude_. Fascinating read if you're really
interested in navigation, whether 300 years ago or present time.


I did read it, but it talked too much about politics and other
matters, and not enough about technical stuff.


Nice putdown.


How so? I was alluding to the fact that some things in aviation have
not changed.


I gave you some tantalizing clues about navigation. Pursue them or
ignore them. Up to you.


At the moment I don't have time to investigate them, but I'll keep
them under consideration.

But you do have time to make aleph null cross posts to USENET. How
convenient.

Cool! I'm glad I'm not the only one left. :)

Nowadays my relationship with stars centers around my 12" Dob, but
every evening I still look up at the sky and think, "okay, which three
stars will give me the best fix".

Three LOP's are your friends. :)

I've been thinking about buying a bubble sextant out of eBay or
somewhere. It would be fun some evening to take a sun shot, get a speed
line, and find out I actually live in South Dakota instead of SW
Montana.

:)

--Walt

BT wrote:
Walt.. you are singing my tune..

I remember Grid Celestial Navigation and those trusty HO249s..
Been a long time since I've looked at an Air Almanac

BT

"Walt" wrote in message
oups.com...

Mxsmanic wrote:
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.

That's the whole reason for waypoints. We live on a sphere but
dead-reckon on a flat surface.

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.

Your original statement was about dead reckoning. That was what I was
responding to.

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.

Just a teary-eyed remembrance from an old fart. I didn't expect much of
a response.


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.

That wasn't my point. I thought you were interested in navigation. Try
reading Dava Sobel's _Longitude_. Fascinating read if you're really
interested in navigation, whether 300 years ago or present time.

--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.


Nice putdown.

I gave you some tantalizing clues about navigation. Pursue them or
ignore them. Up to you.

--Walt

Alrighty.

I have been trolled.

Thank you. That which does not kill me makes me stronger.

--Walt

BT wrote:
As for sextants.. I must be an old guy then.. as I have crossed the oceans
of air, relying on the celestial realm, my trusty sextant, a good watch and
lots of math.

BT

Mxsmanic wrote:

Walt writes:


Good point. I read it as saying, "The B-52 is an important part of the
inventory and you're not."


Nope, that's almost the opposite of what I intended.


But it still hurt.


The least complimentary interpretation is not neccesarily the right
interpretation.


By your own admission, you don't have time to be trite. Instead,go read
up on:

Navigation
Spherical Trigonometry
Trim
Weight and Balance
Aircraft Engines
Aerodynamics
GPS
WAAS
LNAV
etc., etc.

These are all areas in which you have made egregious errors in your
posts, obviously from knowing just enough to be dangerous, and stupid.

By your own admission, the information you glean from USENET is suspect,
so you might wish to consider a moratorium on the waste of your own time.

Instead, spend more time researching your topic, and less time
exercising your digits on the USENET keyboard before you ask inane
questions.

MSFS is basically video eye candy, with little basis in reality, other
than its representation of pretty pictures. If you insist on simming
without trying reality, you might at least consider a simulator that
makes at least SOME attempt at real world physics, like X-Plane. Though
from your constant whining about your busy schedule you haven't the time
to operate it correctly.

Then get back to us. And stop cross posting. In a generous mood, I'd
classify you as a student. Post at rec.aviation.student, if at all.

Should you ever make it back to the states, please do e-mail me. I'd be
more than happy to let you try everything you think you know in my own
aircraft.

Rip

On Thu, 04 Jan 2007 22:59:28 GMT, A Lieberma
wrote:

Blanche wrote in
:

Those of us in the US read them, all of them, cover to cover.
Repeatedly. And get tested on them on a recurring, regular basis. You
want to ask questions? Fine, but having access to the FARs - which you
do -- and reading them -- which you refuse to do -- are the the ground
rules for being here.

Unfortunately, as long as some keep feeding this troll, he won't have a
need to read the FAR's, AIMS or any other reference that's been provided to
him.

Don't like the rules of the game? Go play another one, somewhere
else, with someone else. Stop wasting bandwidth.

Manowar, do I agree with this, but some folks really disagree with me when
I say they are wasting their time with this dude. But of course, I am
being told that I am destroying my "reputation" (whatever that reputation
that I so care little about) trying to bring some sanity back to this
group.

Blanche, been singing your tune for about 3 months now..... Only way to
get rid of him is to not answer his questions.

Allen


This is an apology to Allen Lieberma for a previous reply of mine. I
was out of line.

By your warning against mxs (or was it me?), I had felt singled out,
and inferred reasons external to this news group, (answering in that
direction). But that was not so.

I had asked a question concerning leaning, in a thread which was
revolutionizing its method. I am not a pilot, and felt like a troll
doing it. So your words might be interpreted as directed at others so
as not to feed me an answer. That was not what you meant. And a
complaint of mine is the feeding nature of discussion on the usenet.
Not enough of it. There are certain rules, however, by which that
should be done. My reply does not fit them. In that regard I think
we agree.
--
Michael