On Tuesday, September 26, 2017 at 2:51:19 PM UTC-7, wrote:
The Southwest aircraft descend early because they are going into Chicago Midway and O'hare runs the show. Same thing happens at Dallas Love and DFW.. When ATC builds the arrivals (STARs) and departures (SIDS) the big airports get priority, the smaller (Midway, Love) airports have their terminal procedures built around them. Early descents WELL outside of the Class B airspace is very normal and required to get under/around the traffic going into the major airports. Any clubs that operate near B and busy C airspace should have a committee that meets occasionally with the ATC folks, dialogue goes a long way. We (TSA) notify ATC every time we fly and a note is attached to the Love Field ATIS/AWOS describing glider operations south of the class B.

Knowing the arrival points and typical altitudes should be common and required knowledge of all club members. On another note, 500' separation is all ATC is required between IFR and VFR aircraft. If your not accustomed to a 500' pass it will appear very, very close. When I fly alone during the week I monitor the appropriate Regional Approach frequency just for situational awareness, I have a transponder, ATC sees me and I hear them occasionally move IFR traffic around me. Some of the passes are no more than 500', but legal.

WR

It was a United flight that landed on 09L at O'Hare. Don't know if that changes things or not. It was maybe 300' vertical separation after everyone evaded. The trajectories looked like they were headed for zero separation in altitude. The horizontal separation was anywhere from 0 to a few hundred feet - half a thermal width or less.

I can't Imagine ATC would do that on purpose with a circling glider that's climbing, but maybe that's not what you meant.

Andy