Friday, September 22, 2017

Mountain Flying, Explained, Again

Here is another video describing how airplane pilots can get in trouble flying near mountains.


It is amusing in at least two ways.  First, it actually contains some humor, which is unusual for a safety video.  But it also contains a fair amount of misinformation, which always brings a smile to my face.

We went through this with AOPA, whose Air Safety Foundation made three attempts to create a lesson on Mountain Flying for power pilots. The final version was OK, and they get credit for correcting their initial errors.

You can’t blame the guys in this video for trying to keep ignorant power pilots away from the turbulence and sink. But why can’t they ever make the distinction between turbulence and sink?  And why don’t they ever mention how smooth it can get?

And, of course, they never explain why some pilots are actually attracted to mountain waves.

Here’s a challenge.  Let’s collect a list of inaccuracies in the comments. I’ll go first.

Thanks to Andy G for finding the video.

4 comments:

    PMSC Member said...

The ripples in a pond and the shaking rope are horrible analogies, because they illustrate traveling waves, not standing waves.

The key to understanding mountain waves is knowing that they don't move.

Moshe said...

Shaking a rope that is tied to a fixed spot on the other end can result in standing waves, but I doubt that this example is useful for helping the average person understand mountain waves. Ripples in a pond as a result of throwing in a stone are of course not standing waves. But persistent stationary ripples in a shallow stream downwind of rocks are an excellent example.

Moshe said...

I meant "downstream" of course...

Moshe said...

Now that I've actually watched the video: it's better than I expected. They do emphasize that the wind blows right through the stationary lenticular clouds. (Although the wind is not always from the West as they seem to say at 2:40!)

The moving images of rolling clouds are cool! But are they mountain wave rotor clouds? They move downwind in that clip. Perhaps it's from a thunderstorm's gust front.

The big doozie is at 3:55, when they say that "violent turbulence" is also found in the ups and downs associated with the lenticulars. And at 4:35 they call updrafts "hazards", along with the downdrafts.

Fun to hear Rod Machado later in the video. Their call for a "defensive" approach to a mountain from the lee side is laudable, even if their geometry ("135 degrees") may be quibbled with. And remember the video is aimed at airplane pilots. Such a short video is not the place to suggest that one find the wave lift and work it (which I've done many times in an airplane).