Near midair collision between air carrier medium large transport and gliders.

Attributes
ACN	88333
Time
Date	198805
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : jot
State Reference	IL
Altitude	msl bound lower : 7300 msl bound upper : 7300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord tower : stl
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Sail Plane
Flight Phase	cruise other other
Flight Plan	None
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 225 flight time total : 9000 flight time type : 5000
ASRS Report	88333
Person 2
Function	flight crew : single pilot
Qualification	pilot : student
Supplementary
Primary Problem	Ambiguous

Narrative:

On descent into chicago midway at approximately 5 NM southeast of jot while on a vector heading of 050 degree at 7300' MSL we passed through a group of 3 gliders. We missed the glider on our right by approximately 200' laterally. We passed directly over the other 2 gliders, missed them by 500' vertically. No radar traffic warning was issued. An airlines medium large transport (same route) descending in front of us advised approach of the presence of a light aircraft just south of the jot VOR at 5500' MSL. As we approached jot VOR we spotted this aircraft at 12 O'clock descending. I believe this was the tow plane. Just after spotting this aircraft we ran through the gliders. Evasive action was taken. No injuries. The chicago TRACON supervisor stated the on duty controller did not see the gliders or tow plane on radar.

Original NASA ASRS Text

Title: NMAC BETWEEN ACR MLG AND GLIDERS.

Narrative: ON DESCENT INTO CHICAGO MIDWAY AT APPROX 5 NM SE OF JOT WHILE ON A VECTOR HEADING OF 050 DEG AT 7300' MSL WE PASSED THROUGH A GROUP OF 3 GLIDERS. WE MISSED THE GLIDER ON OUR RIGHT BY APPROX 200' LATERALLY. WE PASSED DIRECTLY OVER THE OTHER 2 GLIDERS, MISSED THEM BY 500' VERTICALLY. NO RADAR TFC WARNING WAS ISSUED. AN AIRLINES MLG (SAME ROUTE) DESCENDING IN FRONT OF US ADVISED APCH OF THE PRESENCE OF A LIGHT ACFT JUST SOUTH OF THE JOT VOR AT 5500' MSL. AS WE APCHED JOT VOR WE SPOTTED THIS ACFT AT 12 O'CLOCK DESCENDING. I BELIEVE THIS WAS THE TOW PLANE. JUST AFTER SPOTTING THIS ACFT WE RAN THROUGH THE GLIDERS. EVASIVE ACTION WAS TAKEN. NO INJURIES. THE CHICAGO TRACON SUPERVISOR STATED THE ON DUTY CTLR DID NOT SEE THE GLIDERS OR TOW PLANE ON RADAR.

Data retrieved from NASA's ASRS site as of August 2007 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.