Narrative:

ATC had cleared us to climb to 12000' MSL. Copilot read back 12000'. Pilot climbed to 12000'. At 11700' ATC said he had cleared us to 10000', left us at 12000' while checking the scope. ATC then cleared us to 10000' with expedited descent. We were informed that an air carrier was climbing through 11700', 4 mi in trail of us. We leveled at 10000' within 2 mins. Copilot asked ATC if we had set off any alarms. ATC said negative. Callback conversation with reporter revealed the following: went over sequence of events with reporter to try to ascertain for sure if the ATC jurisdiction was ZAU or ord departure control. Explained that ZAU would need 5 mi sep, but departure controller would only need 3 mi to be legal. After our discussion the reporter decided that they were still with departure controller and were changed to ZAU after getting back down to 10000'. I advised him I would reflect the change in his report. He has had no further follow up from FAA. We talked about the hearback problem in ATC, and he said that he hears many pilots and controllers who do not seem to use proper radio procedure and phraseologies.

Related reports:

Google
 

Original NASA ASRS Text

Title: POTENTIAL LOSS OF SEPARATION BETWEEN CORP ACFT AND TRAILING ACR CLIMBING TO SAME ASSIGNED ALT. OPERATIONAL DEVIATION.

Narrative: ATC HAD CLRED US TO CLB TO 12000' MSL. COPLT READ BACK 12000'. PLT CLBED TO 12000'. AT 11700' ATC SAID HE HAD CLRED US TO 10000', LEFT US AT 12000' WHILE CHKING THE SCOPE. ATC THEN CLRED US TO 10000' WITH EXPEDITED DSCNT. WE WERE INFORMED THAT AN ACR WAS CLBING THROUGH 11700', 4 MI IN TRAIL OF US. WE LEVELED AT 10000' WITHIN 2 MINS. COPLT ASKED ATC IF WE HAD SET OFF ANY ALARMS. ATC SAID NEGATIVE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: WENT OVER SEQUENCE OF EVENTS WITH RPTR TO TRY TO ASCERTAIN FOR SURE IF THE ATC JURISDICTION WAS ZAU OR ORD DEP CTL. EXPLAINED THAT ZAU WOULD NEED 5 MI SEP, BUT DEP CTLR WOULD ONLY NEED 3 MI TO BE LEGAL. AFTER OUR DISCUSSION THE RPTR DECIDED THAT THEY WERE STILL WITH DEP CTLR AND WERE CHANGED TO ZAU AFTER GETTING BACK DOWN TO 10000'. I ADVISED HIM I WOULD REFLECT THE CHANGE IN HIS RPT. HE HAS HAD NO FURTHER FOLLOW UP FROM FAA. WE TALKED ABOUT THE HEARBACK PROB IN ATC, AND HE SAID THAT HE HEARS MANY PLTS AND CTLRS WHO DO NOT SEEM TO USE PROPER RADIO PROC AND PHRASEOLOGIES.

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.