Mountain flying knowledge required?

"Peter Duniho" wrote in message
...
"Chris W" wrote in message
news:gj%ae.640$zv1.481@lakeread07...
Is there an altitude above the ridge line at which the "mountain wave"
effect isn't significant?

Probably would be pretty negligible at 23,000 miles. For example.

Seriously though, yes...you can sometimes fly high enough to avoid the
wave. But that depends on the height of the terrain, the strength of the
wind, and of course the type of aircraft. There is no reliable way to
know ahead of time how high you need to fly to avoid it.

That said, there's being high enough to get all the way out of any
noticeable effects of the wave, and then there's being high enough to
avoid the wave forcing you too close to the terrain. The former may be
impossible, depending on the situation. The latter is usually possible.
I have rarely experienced altitude excursions of greater than 2000-3000
feet as a result of mountain wave, so that's a pretty reliable margin for
crossing ridges.

Of course, there is the question of whether mountain wave can actually
push you into the ground. I've never actually heard of that happening,
and for it to do so, the part of the air mass you're flying in would have
to hit the ground as well. That happens in microbursts, or under virga,
for example, but you'd have to be pretty darn close to the ground in the
first place for a mountain wave to push you into it.

From a practical perspective, a couple of things to consider: higher up
may provide less turbulence (though, don't try to fly through a rotor
cloud). Also, if you want to most efficiently use the mountain wave to
your advantage, pitch up and slow down while it's making you go up, and
pitch down and speed up while it's making you go down. This will increase
the magnitude of your altitude changes, but you'll be spending less time
during the "bad" down areas and more time during the "good" up areas.
Fighting the mountain wave is just that: fighting. And no one wins a
fight with Mother Nature.

Of course, in practice you may have upper and lower limits to acceptable
altitudes, and those need to be taken into account. But inasmuch as you
can allow your altitude to vary with the wave, let it.

Pete


Mountain wave systems extend to and often into the stratosphere so it is
unlikely that you can fly above them unless you have a new airplane that we
haven't been told about :-).

Mike
MU-2

Peter Duniho wrote:
"Stefan" wrote in message
...

Depending on the wind situation, you can expect downdrafts of 10 fpm or
even more. No light single will outclimb this, even less at altitude.


You need to recalibrate your vertical speed reference. 10 fpm (or 20 fpm,
as you wrote elsewhere) is 10 feet per minute. That's nothing, and quite a
bit less than any actual up or down that one might find due to mountain wave
or similar effects.

I have no idea what you meant to write, but it's absolutely false that "no
light single will outclimb" 10 fpm downdraft.

Pete

Peter Duniho wrote:

10 feet per minute.
....
I have no idea what you meant to write,

I've meant 1000 to 2000 fpm.

Stefan

Morgans wrote:
"Toño" wrote


Not according to Sparky Imeson....

"...the rotor cloud will be downwind from the mountain range and extend
anywhere from the earth's surface to up to mountain-top level".

--p.63 of "Mountain Flying" by Sparky Imeson
Antonio


There is some disagreement with this, and here is a clip:
Normally the rotor clouds is centered beneath the lenticular cloud. Most
often it extends anywhere from ground level to mountaintop level, but is
frequently observed up to 35,000 feet. Destructive turbulence from the rotor
rarely exists more than 2,000-3,000 feet above mountaintop level.

Well? Your last sentence says it..."Destructive turbulence from the
rotor rarely exists more than 2,000-3,000 feet above mountaintop level."
I see no "disagreement" about it.


My point is, just because you clear the ridge, there are still dangers that
can ruin your day,snip

I agree and never stated otherwise.

However, the OP was wondering whether he should take a "mountain flying"
course in order to make a cross-country trip at altitudes of 16-19,000
ft. My contention was that this was not *mountain flying* per se and
that he was wasting his time thinking that a mountain flying course
would in any way prepare him for the trip.

The topic is not "are there dangers at high altitudes" as some here seem
to be trying to make it; it is: "would one benefit by a mountain flying
course if one were flying at high altitudes?" At least, that's how I
read it.

Thanks for the great link!

Antonio

Dylan Smith wrote:
In article , Tango Whiskey wrote:

read a good mountain flying book like Sparky Imerson's you'll be good to go


Sparky Imeson has a mountain flying website with lots of good stuff:

http://www.mountainflying.com/


Yes! and here is the link to his free download on cross-country planning....

http://www.mountainflying.com/xcguide.htm

"Morgans" wrote in message
news


There is some disagreement with this, and here is a clip:
Normally the rotor clouds is centered beneath the lenticular cloud. Most
often it extends anywhere from ground level to mountaintop level, but is
frequently observed up to 35,000 feet. Destructive turbulence from the
rotor
rarely exists more than 2,000-3,000 feet above mountaintop level.

http://www.mountainflying.com/mountain_wave2.htm

My point is, just because you clear the ridge, there are still dangers
that
can ruin your day, if the winds are right. Further down in the article,
this author talks about rotors that do not have a visible cloud.

If the wind is blowing strong, close to perpendicular to the ridge, best
wait until early the next day, and see if the winds are calmed down.

Hey, I just read, and remember. I have no idea if what everyone says is
true. I would rather be safe, than sorry. YMMV
--
Jim in NC

Hmmmm, I've been through the rotor a few times -- while yanking and
banking on the end of a 200' length of towrope behind a tow-plane. The first
time is the worst. After that you remember to breathe and you don't suck
quite as hard on the seat cushion.
When you're headed for the primary wave developed on the east slope of
the Sierra, the rotor is unavoidable. Some folks, with more skill than I
possess, ride thermals up into the secondary wave and, when high enough
slide over to the primary.
I guess I never thought of the rotor as destructive. Maybe I shouldn't
do that again.

Stefan wrote:

Peter Duniho wrote:

10 feet per minute.

...

I have no idea what you meant to write,


I've meant 1000 to 2000 fpm.

Still isn't fatal.

Newps wrote:

I've meant 1000 to 2000 fpm.

Still isn't fatal.

Nobody talked about fatal. You just can't outclimb this at altitude with
a light, non turbo charged single. So it may indeed become fatal, and
has so on a regular basis, for those who don't know how to behave in the
mountains.

Stefan

"Mike Rapoport" wrote in message
.net...
Rotors do not extend much above the ridgetops. The waves themselves are
smooth until reaching the tropopause except the extreme case of breaking
waves.

Before Mike, Jim in NC wrote:

The waves extend way up past the peaks, and so do rotors.

I guess it depends on your definition of "way past". As per my other quoted
post, about destructive part of the rotor going to 2 thousand over the
ridge, I think that is way over. Plus, I want to be well above where the
rotor is still destructive, like another couple thousand. That is really
way past to me. YMMV

I just want people to know that if they are thinking of going over a pass
with only a couple thousand to spare, if the wind is blowing just right,
they could be in big trouble, whether they see it or not. Right?
--
Jim in NC

Toño wrote:
Blanche wrote:

And what happens if the engine conks out? Where do you land? How do
you land?

Maybe he should also take glider lessons, mountain survival,
parachuting, and aerobatics prior to the flight. I mean, those
disciplines have just as much relevance if not more should a forced
landing be immanent.

My response addressed your comment about "flying in the mountains".
And yes, if you're going to fly "in the mountains" in a single (unless,
of course, that single engine is attached to an F16) you really should
have some knowledge of mountain survival.

How does a knowledge of mountain flying help you to land with and engine
out? And how would that differ from any other no-engine landing?

OK, you're at 16K over the I-70 in Colorado west of Denver. Let's
say somewhere between Georgetown and Silverton. What are you going
to do? (And following I-70 between Denver and Glenwood Springs is
the absolute worst action you can take). If you've only read Sparky's
book it's not going to help much.

About the only thing I could think of would be to try to estimate winds
and direction based on terrain features. Read Sparky's book and you have
some theory to work off of but, really....do you think that this would
sufficiently arm you for an encounter with the winds in the mountains?
If you do then you have never flown *in* the mountains!

Please remember, I'm the one who said reading Sparky's book and
nothing else is not a good idea. Flying in the mountains...hm...
Half the time I'm in the air, I'm very close to mountains. Personally,
I prefer NOT to be "in the mountains". Above, between, sure.

As far as *where* you land...you land wherever you can; as in
non-mountainous terrain.

Again I respond -- if all you've ever done is read the book you're
not prepared.

And when that happens, all of a sudden you need to worry about
mountain waves, density altitude, valley winds, etc. Calculate
glide distance from 16K and tell me where & how you're going to
land.

Well...if you know how far you can glide at 1000 ft you can multiply by
sixteen. But that calculation would only give you the no-wind
theoretical distance. It also something every pilot should know
regardless of whether they are in the mountains or not.

And, come on! Are you really going to pull out the ole' whiz wheel and
think about "...density altitude, valley winds, etc." when you are
dead-sticking it to a suitable landing site? Generally, you *might*
have one place to land that is suitable and you can bet your gold-plated
E6B you'll take it regardless of the "density altitude".

I don't own a "whiz wheel". Well, I do. I just don't know where it
is these days. But you point out that "you *might* have one place to
land that is suitable"...better yet, you may not have *any* place
to land but you still need to get down.

But as the OP stated, his flight plan was over mostly flat land. In
fact, pretty much follows I-40 to I-25 (watch out for the MOA south of
Pueblo -- I-25 goes right thru it) which is very practical.