On Wednesday, October 10, 2018 at 4:47:59 PM UTC-7, Roy B. wrote:
Cindy:
That is interesting, but wouldn't ATC want to divert high speed traffic away from the area below the glider in wave? That's a pretty big speed bump to hit at 500kts.
ROY

Usually the glider folk were wanting the windows on weekends. In our case, the airspace was often not (for a few hours) Dept of Defense use - it was released for civil use - so airliners wanted to go Direct... and save a ton of fuel. They're only running ~300 kts. And what's a little oscillation in cruise alt to a Boeing?

I am guessing that there is small enough pressure change in the peak and valley of the wave that the transponder reports to ATC don't show any alt deviation. And the autothrottles are doing their best to mitigate. Combine that with the 100' increment of transponder 'accuracy' and the local ATC boys being pretty well versed in the local weather phenomena. No one gets too upset, literally and figuratively.

The FLXXX cruise alts locally are mostly Above the rotor layer that lies under the wave apogee. Yes, there might be the "little buzz" in the upper transition trough - windward of the primary, but I have seldom encountered it. Even when wanting to run a level altitude and using that location.

The "local" ATC facility is darn well trained, and their primary mandate from the facility supervisor (who I had taken wave soaring) was " make it work for the most participants" == a helluva great outlook. Hence, if we could stay predictable at a block FL assignment, an airliner would run under us.

This was after we had established a track record of predictability and compliance. Keeping a clean record with ATC can be morphed into more privileges over time.

Soar safely,

Cindy B