Aztec down in Montana wilderness

[bbchien]

"(d) all of the above"

 

[MauleSkinner]

Obviously you’re not going to see them. Lenticulars are indicative of the turbulence associated with a standing wave, whether imbedded inside cloud, or in clear air.

Lenticulars are also indicative of the glassy smooth extreme up and down drafted associated with a standing wave.

 

[Rick A]

Lenticulars are also indicative of the glassy smooth extreme up and down drafted associated with a standing wave.

Yes, you don't really know what you've gotten yourself into, until there. Nor do you want to. I'm sure most of them are smooth. It's where they change direction (IMO) is where the trouble lurks.

The most memorable ride in my life (severe turbulence - temporarily out of control) was riding a strong down wave one or two thousand feet above a solid cloud layer. In clear smooth air, until 10 or 15 seconds inside an invisible rotor located at the very low point in the trough, where the downdraft soon reversed into a smooth strong updraft. The rotor was located just touching the clouds enough to rip off little scrappy pieces of the top of the cloud layer beneath. Never got into the cloud tops, but was right there.

 

[MauleSkinner]

Yes, you don't really know what you've gotten yourself into, until there. Nor do you want to. I'm sure most of them are smooth. It's where they change direction (IMO) is where the trouble lurks.

what you describe below is one of the ways to visually identify rotor to avoid it.

The most memorable ride in my life (severe turbulence - temporarily out of control) was riding a strong down wave one or two thousand feet above a solid cloud layer. In clear smooth air, until 10 or 15 seconds inside an invisible rotor located at the very low point in the trough, where the downdraft soon reversed into a smooth strong updraft. The rotor was located just touching the clouds enough to rip off little scrappy pieces of the top of the cloud layer beneath. Never got into the cloud tops, but was right there.

 

[Rick A]

what you describe below is one of the ways to visually identify rotor to avoid it.

Yes, now I know. Didn't notice those small scrappy torn clouds until I was abeam them, moments before encountering the rotor. From above I'm sure they were blended in and camouflaged by the lower cloud deck. Probably wouldn't have seen them even if I knew enough to look (which I didn't). Figured I'd be entering the clouds and continue descending at Vy. Wasn't too worried as I was around 8000' above the mountain tops. Climbing out of this situation would have been impossible, the solution (duh) would have been to avoid being there in the first place.

At the beginning of the down wave, while pulling the nose up and trying to maintain the assigned altitude, the groundspeed had decayed down to 40 kts., and ATC asked why. Informed them of the strong downdraft, and the likelihood I'd be forced to descend lower.

Entering the rotor ATC asked if I would like to declare an emergency, and consider diverting to the closest airport (KMSV) which is located downwind of the Catskill mountains. At that point I can only guess what the groundspeed was showing, but likely something less than 40 kts., prompting them to ask.

While answering negative and attempting to talk, my voice in the headset sidetone was mostly grunts and sounded like trying to talk while getting repeatedly hit with punches to the body, as loose stuff (including a flight bag, dirt and debris off the floor) was flying around the cockpit. I was very glad the turbulence suddenly ceased (didn't last long), and the plane proceeded to accelerate and briskly climb into a strong and smooth up wave, back to the assigned IFR altitude.

That flight happened 36 years ago, and instilled a very healthy respect for winds and mountains that has served me well ever since.