grumman needs a polish
 

Good news on the Pilot.

But what exactly is a "'sink hole' of air pressure"?

I must have skimmed over that bit in my books.

One less AgCat around the traps. That one was a pretty good example. :(

grumman needs a polish
 

Air pressure "sink holes" are described in detail in the Manual of Meteorology. They are the reportedly the prime cause of "plummeting" - aka "death dive" and "tail-spin"

Huh.....Thanks Rounds, I really did skim, and it was a long time ago! No excuse.

I will have to go back have a better look.

And while I don't wish to thread hijack, makes me wonder how many ppl have forgotten a lot of the theory over the years.

These sink holes you describe are probably more like mountain rotors.