Narrative:

Ord departure control asked us to turn on our transponder after takeoff. Since it is always on when airborne, we switched to #2 transponder. After a couple more calls, departure control finally got our squawk. We were assigned a heading of 070 degrees, followed shortly by 060 degrees and level at 13000'. After a long time, the first officer and I discussed whether they forgot us, when they switched us to ord center. The new controller asked our altitude. We told him. He then asked our position. We said 35 mi west of keeler. He still couldn't find us and asked us to identify. We did. Then he asked us to identify again. We did. We also switched between #1 and #2 and idented several times. Around 15 mi west of keeler we were cleared to climb. We assumed they had us on radar. At FL290 on another center frequency, we asked the controller if he saw our squawk. He said yes. We asked to switch to #1 transponder. He said he saw that one too--everything appeared normal. We decided not to write a maintenance complaint on the transponder since the last controller said it was ok and no other complaints during the rest of the flight. 2 hours later, I got a call from company asking about a transponder problem in chicago. I relayed the same story as above to him. He said he was called by chicago center re: our flight with no transponder and 2 close calls. We were never informed by center about the no transponder or either of the 2 close calls, nor did we see anyone (close or far) during the whole episode. Our first indication came from a call from company.

Related reports:

Google
 

Original NASA ASRS Text

Title: THE ACFT MAY OR MAY NOT HAVE HAD A TRANSPONDER PROBLEM. UNABLE FURTHER INFORMATION FROM REPORTER.

Narrative: ORD DEP CTL ASKED US TO TURN ON OUR XPONDER AFTER TKOF. SINCE IT IS ALWAYS ON WHEN AIRBORNE, WE SWITCHED TO #2 XPONDER. AFTER A COUPLE MORE CALLS, DEP CTL FINALLY GOT OUR SQUAWK. WE WERE ASSIGNED A HDG OF 070 DEGS, FOLLOWED SHORTLY BY 060 DEGS AND LEVEL AT 13000'. AFTER A LONG TIME, THE F/O AND I DISCUSSED WHETHER THEY FORGOT US, WHEN THEY SWITCHED US TO ORD CENTER. THE NEW CTLR ASKED OUR ALT. WE TOLD HIM. HE THEN ASKED OUR POS. WE SAID 35 MI W OF KEELER. HE STILL COULDN'T FIND US AND ASKED US TO IDENT. WE DID. THEN HE ASKED US TO IDENT AGAIN. WE DID. WE ALSO SWITCHED BTWN #1 AND #2 AND IDENTED SEVERAL TIMES. AROUND 15 MI W OF KEELER WE WERE CLRED TO CLB. WE ASSUMED THEY HAD US ON RADAR. AT FL290 ON ANOTHER CENTER FREQ, WE ASKED THE CTLR IF HE SAW OUR SQUAWK. HE SAID YES. WE ASKED TO SWITCH TO #1 XPONDER. HE SAID HE SAW THAT ONE TOO--EVERYTHING APPEARED NORMAL. WE DECIDED NOT TO WRITE A MAINT COMPLAINT ON THE XPONDER SINCE THE LAST CTLR SAID IT WAS OK AND NO OTHER COMPLAINTS DURING THE REST OF THE FLT. 2 HRS LATER, I GOT A CALL FROM COMPANY ASKING ABOUT A XPONDER PROB IN CHICAGO. I RELAYED THE SAME STORY AS ABOVE TO HIM. HE SAID HE WAS CALLED BY CHICAGO CENTER RE: OUR FLT WITH NO XPONDER AND 2 CLOSE CALLS. WE WERE NEVER INFORMED BY CENTER ABOUT THE NO XPONDER OR EITHER OF THE 2 CLOSE CALLS, NOR DID WE SEE ANYONE (CLOSE OR FAR) DURING THE WHOLE EPISODE. OUR FIRST INDICATION CAME FROM A CALL FROM COMPANY.

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.