Fatal crash Arizona

On Wednesday, May 7, 2014 6:28:41 AM UTC-7, Mike the Strike wrote:
...now redo your calculations while flying through 8 knots of sink.



Mike

...and calculate the height loss while making a 180-degree turn. Taking the 12.8 seconds just mentioned at 800 feet per minute gives you a height loss of 170 feet from the airmass movement alone, plus whatever you add for the glider itself. Safety margins in severe sink disappear frighteningly quickly.

Mike

On Wednesday, May 7, 2014 9:35:46 AM UTC-4, Mike the Strike wrote:
On Wednesday, May 7, 2014 6:28:41 AM UTC-7, Mike the Strike wrote:

...now redo your calculations while flying through 8 knots of sink.







Mike



..and calculate the height loss while making a 180-degree turn. Taking the 12.8 seconds just mentioned at 800 feet per minute gives you a height loss of 170 feet from the airmass movement alone, plus whatever you add for the glider itself. Safety margins in severe sink disappear frighteningly quickly.



Mike

Now throw in wind shear and tailwind component when failure to anticipate leads to turning in the wrong direction.
Double AARRGGHH!!
UH

Can you really get 8kts of sink at 200ft? Where is the air going, into the ground?

Boggs

Can you really get 8kts of sink at 200ft? Where is the air going, into the
ground?


Having experienced two in-pattern microbursts, I'd say, "Yes, indeed!" to Q1.

As to Q2, as soon as I finish interviewing the bugs on my leading edges and
car windshield, I'll post the interview on YouTube. :-)

Bob W.

P.S. Putting my More Seriously Hat, elsewhere in this thread someone else
pointed out the relative uselessness of L/D in patterns when "real sink" was
an issue. Thoughtful pilots will agree. Maybe this is more of a "routine
issue" in (say) the western U.S. than elsewhere in the country, but I have my
doubts when it comes to (e.g.) wavish pattern conditions (e.g. Cumberland, MD;
Petersburg, WV).

On 5/7/2014 11:18 AM, Waveguru wrote:
Can you really get 8kts of sink at 200ft? Where is the air going, into the ground?

Dunno, but one time I was checking out a new club member in a Blanik. We
were on short final, rwy 16 at 3B3, when I said something like "this is
perfect, the right position at the right speed". About 5 seconds later I
couldn't see the rwy 'cause the tree tops were in the way. The thing
that saved us was the extra speed in anticipation of the wind gradient.

Tony "6N"