Narrative:

I was on the motif arrival to mdw talking to ZAU. I cannot recall the frequency; but the last one before handoff to approach. We were originally cleared to cross 5 mi south of jot at 6000 ft and were then cleared to cross 10 mi south of jot at 7000 ft; which we complied. Flight conditions were clear of clouds and hazy with flight visibility around 5 mi. We were level at 7000 ft indicating 250 KTS with the first officer flying. I was doing my normal scan for traffic when just ahead; approximately 11 O'clock position; a sailplane appeared straight-on in a steep right bank. It went past my side window still in the bank; but very close; maybe 200 ft left and less than 50 ft above. This all happened in an instant; but I actually saw the pilot in his seat. The sailplane was a t-tail single seat version. My first officer also saw the aircraft for an instant after he must have heard me say an '&^%$#.' there was absolutely no time for an evasive maneuver. The aircraft appeared out of nowhere and its cross section straight-on in hazy conditions made it nearly impossible to see. I called the center and said I had a close call with a sailplane and was asked how close. I said less than 500 ft; and he acknowledged saying that no aircraft was being painted near me. I was then handed over to chicago approach control and also told him about the sailplane activity on the arrival; and he said he was getting a hit every once in a while in that area. I believe that if we were 100 ft left and a few ft higher; a collision would have occurred. As a crew; we were actively scanning and preparing for 'normal' vectors to the approach. I saw no fault in ATC whatsoever. I would like to know why sailplanes are allowed to fly on a known arrival route to one of the busiest airspaces in the country; especially without a transponder. I have wracked my brain trying to think of what I could have done differently; but find nothing. We were a sterile cockpit with all aircraft lights. I just did not see the aircraft coming; and any reaction would have been too late. The gliders have every right to be flying; but maybe a change in the arrival route away from glider fields or an altitude cap for them in that area should be looked at. Also; training to the glider pilots in the area ought to be given; outlining the high density arrival rtes to the chicago area. It was a chilling event to my first officer and me. It was a very close call.

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Original NASA ASRS Text

Title: B737 FLT CREW WITH ZAU AT 7000 FT EXPERIENCED NMAC WITH UNRPTED SAILPLANE DURING ARR TO MDW.

Narrative: I WAS ON THE MOTIF ARR TO MDW TALKING TO ZAU. I CANNOT RECALL THE FREQ; BUT THE LAST ONE BEFORE HDOF TO APCH. WE WERE ORIGINALLY CLRED TO CROSS 5 MI S OF JOT AT 6000 FT AND WERE THEN CLRED TO CROSS 10 MI S OF JOT AT 7000 FT; WHICH WE COMPLIED. FLT CONDITIONS WERE CLR OF CLOUDS AND HAZY WITH FLT VISIBILITY AROUND 5 MI. WE WERE LEVEL AT 7000 FT INDICATING 250 KTS WITH THE FO FLYING. I WAS DOING MY NORMAL SCAN FOR TFC WHEN JUST AHEAD; APPROX 11 O'CLOCK POS; A SAILPLANE APPEARED STRAIGHT-ON IN A STEEP R BANK. IT WENT PAST MY SIDE WINDOW STILL IN THE BANK; BUT VERY CLOSE; MAYBE 200 FT LEFT AND LESS THAN 50 FT ABOVE. THIS ALL HAPPENED IN AN INSTANT; BUT I ACTUALLY SAW THE PLT IN HIS SEAT. THE SAILPLANE WAS A T-TAIL SINGLE SEAT VERSION. MY FO ALSO SAW THE ACFT FOR AN INSTANT AFTER HE MUST HAVE HEARD ME SAY AN '&^%$#.' THERE WAS ABSOLUTELY NO TIME FOR AN EVASIVE MANEUVER. THE ACFT APPEARED OUT OF NOWHERE AND ITS CROSS SECTION STRAIGHT-ON IN HAZY CONDITIONS MADE IT NEARLY IMPOSSIBLE TO SEE. I CALLED THE CTR AND SAID I HAD A CLOSE CALL WITH A SAILPLANE AND WAS ASKED HOW CLOSE. I SAID LESS THAN 500 FT; AND HE ACKNOWLEDGED SAYING THAT NO ACFT WAS BEING PAINTED NEAR ME. I WAS THEN HANDED OVER TO CHICAGO APCH CTL AND ALSO TOLD HIM ABOUT THE SAILPLANE ACTIVITY ON THE ARR; AND HE SAID HE WAS GETTING A HIT EVERY ONCE IN A WHILE IN THAT AREA. I BELIEVE THAT IF WE WERE 100 FT LEFT AND A FEW FT HIGHER; A COLLISION WOULD HAVE OCCURRED. AS A CREW; WE WERE ACTIVELY SCANNING AND PREPARING FOR 'NORMAL' VECTORS TO THE APCH. I SAW NO FAULT IN ATC WHATSOEVER. I WOULD LIKE TO KNOW WHY SAILPLANES ARE ALLOWED TO FLY ON A KNOWN ARR RTE TO ONE OF THE BUSIEST AIRSPACES IN THE COUNTRY; ESPECIALLY WITHOUT A XPONDER. I HAVE WRACKED MY BRAIN TRYING TO THINK OF WHAT I COULD HAVE DONE DIFFERENTLY; BUT FIND NOTHING. WE WERE A STERILE COCKPIT WITH ALL ACFT LIGHTS. I JUST DID NOT SEE THE ACFT COMING; AND ANY REACTION WOULD HAVE BEEN TOO LATE. THE GLIDERS HAVE EVERY RIGHT TO BE FLYING; BUT MAYBE A CHANGE IN THE ARR RTE AWAY FROM GLIDER FIELDS OR AN ALT CAP FOR THEM IN THAT AREA SHOULD BE LOOKED AT. ALSO; TRAINING TO THE GLIDER PLTS IN THE AREA OUGHT TO BE GIVEN; OUTLINING THE HIGH DENSITY ARR RTES TO THE CHICAGO AREA. IT WAS A CHILLING EVENT TO MY FO AND ME. IT WAS A VERY CLOSE CALL.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.