Narrative:

Departing chicago midway, chicago center cleared us to FL2300, gave us a frequency change and told us to expect to level at FL2300. We checked on with the next controller fully expecting a hold down at 230 and were pleasantly surprised when he cleared us to climb to FL310. We remarked about coordination at that time. The first officer was flying, we were VMC but about to enter IMC in about another 10-15 mi. Approaching FL2300 I noticed a small aircraft converging on us at our 10-11 O'clock position. I wasn't sure of his altitude but knew we were converging at a rapid rate. I pointed the traffic out to the first officer who proceeded to slow our rate of climb and I asked center if he had the traffic at our 10 to 11 O'clock. Controller instructed us to maintain FL2300. We were passing FL230.3 at the time and I replied that we would go back down to 230. We stopped our climb at FL230.6 and started to descend. The controller asked our altitude at this time and I read back 23.6. Shortly thereafter the other aircraft went IMC and we lost contact but had no other incident. We were fortunate that we had enough separation and were VMC. Had we been IMC at the time and a little closer, the potential for tragedy was there. We probably could have helped the situation by questioning the second controller when he did not stop us at 230 instead of commenting about it between ourselves. I will in the future. Coordination between the cockpit crew members is always stressed, well I just added another member to my cockpit crew, the ground controller.

Related reports:

Google
 

Original NASA ASRS Text

Title: ACR MLG STOPPED CLIMB TO PREVENT COLLISION WITH SMALL JET AT FL240.

Narrative: DEPARTING CHICAGO MIDWAY, CHICAGO CENTER CLRED US TO FL2300, GAVE US A FREQ CHANGE AND TOLD US TO EXPECT TO LEVEL AT FL2300. WE CHKED ON WITH THE NEXT CTLR FULLY EXPECTING A HOLD DOWN AT 230 AND WERE PLEASANTLY SURPRISED WHEN HE CLRED US TO CLB TO FL310. WE REMARKED ABOUT COORD AT THAT TIME. THE F/O WAS FLYING, WE WERE VMC BUT ABOUT TO ENTER IMC IN ABOUT ANOTHER 10-15 MI. APCHING FL2300 I NOTICED A SMALL ACFT CONVERGING ON US AT OUR 10-11 O'CLOCK POS. I WASN'T SURE OF HIS ALT BUT KNEW WE WERE CONVERGING AT A RAPID RATE. I POINTED THE TFC OUT TO THE F/O WHO PROCEEDED TO SLOW OUR RATE OF CLB AND I ASKED CENTER IF HE HAD THE TFC AT OUR 10 TO 11 O'CLOCK. CTLR INSTRUCTED US TO MAINTAIN FL2300. WE WERE PASSING FL230.3 AT THE TIME AND I REPLIED THAT WE WOULD GO BACK DOWN TO 230. WE STOPPED OUR CLB AT FL230.6 AND STARTED TO DSND. THE CTLR ASKED OUR ALT AT THIS TIME AND I READ BACK 23.6. SHORTLY THEREAFTER THE OTHER ACFT WENT IMC AND WE LOST CONTACT BUT HAD NO OTHER INCIDENT. WE WERE FORTUNATE THAT WE HAD ENOUGH SEPARATION AND WERE VMC. HAD WE BEEN IMC AT THE TIME AND A LITTLE CLOSER, THE POTENTIAL FOR TRAGEDY WAS THERE. WE PROBABLY COULD HAVE HELPED THE SITUATION BY QUESTIONING THE SECOND CTLR WHEN HE DID NOT STOP US AT 230 INSTEAD OF COMMENTING ABOUT IT BTWN OURSELVES. I WILL IN THE FUTURE. COORD BTWN THE COCKPIT CREW MEMBERS IS ALWAYS STRESSED, WELL I JUST ADDED ANOTHER MEMBER TO MY COCKPIT CREW, THE GND CTLR.

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.