Narrative:

On arrival into ord (janesville 1 arrival) level at 12000' MSL, ATC frequency became unreadable. After several attempts were made to contact ZAU on this frequency (128.05), the captain contacted ord approach control on 119.0, our next frequency. After being idented by approach control, the controller immediately issued traffic at 10 O'clock and below us. We saw an medium large transport to our left and below us, passing underneath. The aircraft appeared to be well below us. We acknowledged the traffic and continued on the arrival. Nothing was mentioned of any loss of traffic sep. Days later I learned from pilot group that there had been an investigation into the incident, and that this was in fact a sep problem. At the time of the incident, we were not at all aware of this. The problem was caused by equipment malfunction or a stuck microphone. I was surprised to have to learn of this situation days later, and feel that in a case of inadequate sep the controller should advise both aircraft so a report can be filed promptly. Callback conversation with reporter revealed the following: reporter states he left town after the incident and heard about it from the news media. At first he did not relate it to his flight, then as he thought about it he realized it was the same situation. Pilot group also became aware via the news and contacted the crew members to submit a report. Reporter upset that ATC did not inform the crew so they could report promptly. Feels controllers blew it up to support their needs for new equipment, etc. Although it may have been closer that it looked. He has heard nothing form any FAA personnel to date.

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Original NASA ASRS Text

Title: ACR IN MIXED WX CONDITIONS SIGHTS TRAFFIC CALLED. LATER LEARNS FROM NEWSPAPER THAT THERE WAS LESS THAN STANDARD SEPARATION.

Narrative: ON ARR INTO ORD (JANESVILLE 1 ARR) LEVEL AT 12000' MSL, ATC FREQ BECAME UNREADABLE. AFTER SEVERAL ATTEMPTS WERE MADE TO CONTACT ZAU ON THIS FREQ (128.05), THE CAPT CONTACTED ORD APCH CTL ON 119.0, OUR NEXT FREQ. AFTER BEING IDENTED BY APCH CTL, THE CTLR IMMEDIATELY ISSUED TFC AT 10 O'CLOCK AND BELOW US. WE SAW AN MLG TO OUR LEFT AND BELOW US, PASSING UNDERNEATH. THE ACFT APPEARED TO BE WELL BELOW US. WE ACKNOWLEDGED THE TFC AND CONTINUED ON THE ARR. NOTHING WAS MENTIONED OF ANY LOSS OF TFC SEP. DAYS LATER I LEARNED FROM PLT GROUP THAT THERE HAD BEEN AN INVESTIGATION INTO THE INCIDENT, AND THAT THIS WAS IN FACT A SEP PROB. AT THE TIME OF THE INCIDENT, WE WERE NOT AT ALL AWARE OF THIS. THE PROB WAS CAUSED BY EQUIP MALFUNCTION OR A STUCK MIC. I WAS SURPRISED TO HAVE TO LEARN OF THIS SITUATION DAYS LATER, AND FEEL THAT IN A CASE OF INADEQUATE SEP THE CTLR SHOULD ADVISE BOTH ACFT SO A RPT CAN BE FILED PROMPTLY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR STATES HE LEFT TOWN AFTER THE INCIDENT AND HEARD ABOUT IT FROM THE NEWS MEDIA. AT FIRST HE DID NOT RELATE IT TO HIS FLT, THEN AS HE THOUGHT ABOUT IT HE REALIZED IT WAS THE SAME SITUATION. PLT GROUP ALSO BECAME AWARE VIA THE NEWS AND CONTACTED THE CREW MEMBERS TO SUBMIT A RPT. RPTR UPSET THAT ATC DID NOT INFORM THE CREW SO THEY COULD RPT PROMPTLY. FEELS CTLRS BLEW IT UP TO SUPPORT THEIR NEEDS FOR NEW EQUIP, ETC. ALTHOUGH IT MAY HAVE BEEN CLOSER THAT IT LOOKED. HE HAS HEARD NOTHING FORM ANY FAA PERSONNEL TO DATE.

Data retrieved from NASA's ASRS site as of July 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.