ALT EXCURSION BY C560 CREW CAUSES CONFLICTION WITH B737 AT CRUISE ALT.

Narrative

THE C560 WAS A DEP OFF THE DFW AREA. THE B737 WAS SBOUND OPPOSITE DIRECTION OF THE C560. THE C560 WAS CLBED TO FL270. THE C560 CAME BACK AND REQUESTED FL290 FOR A FINAL. THE B737 WAS SBOUND AT FL290. THE R SIDE ISSUED THE C560 CLB CLRNC TO FL280 AND WAS ISSUED THE B737 TFC. THE C560 READ BACK FL290. IT WAS BELIEVED BY THE R-SIDE THAT THE C560 READ BACK FL280. THE C560 CLBED TO FL290. THE B737 WAS STILL AT FL290 SBOUND HEAD-ON WITH THE C560. I HAD JUST ASSUMED THE D-SIDE AND HAD BEEN ON POS LESS THAN 2 MINS WHEN THE INCIDENT TOOK PLACE. I WAS BUSY ACCLIMATING MYSELF TO THE POS; IE; LOOKING FOR POTENTIAL MANUAL CONFLICTIONS; DETERMINING IF ANY POINT OUTS NEEDED TO BE MADE; CATCHING THE FLT PROGRESS STRIPS UP-TO-DATE; HANDLING CALLS FROM OTHER CTLRS. DURING THIS PERIOD SOMEHOW I NEVER HEARD THE R-SIDE ISSUE THE C560 CLB TO FL280; THUS I WAS UNABLE TO CATCH THE INCORRECT READBACK. THE RECORDING EQUIP SHOWS THAT THE READBACK CAME THROUGH; BUT I NEVER HEARD IT. I BECAME AWARE OF THE PROB WHEN I GLANCED AT THE RADAR SCOPE AND SAW THAT THE C560 AND THE B737 WERE HEAD-ON APPROX 10 MI APART. CONFLICT ALERT HAD NOT GONE OFF YET. THE C560 WAS OUT OF FL287 CLBING STILL. I IMMEDIATELY INFORMED THE R-SIDE WHO IMMEDIATELY DSNDED THE C560 BACK TO FL280. THE B737 WAS CLBED TO FL310. THE C560 SAID HE THOUGHT HE HAD BEEN CLRED TO FL290. THE B737 DID RECEIVE AN RA (TCASII) AND WAS STARTING TO MAKE A TURN AWAY FROM THE C560. THE C560 PLT DID CALL IN LATER AND ADMITTED SUPPOSEDLY THAT HE WAS NOT POSITIVE AS TO HIS ASSIGNED FLT LEVEL. A PLTDEV IS SUPPOSED TO BE FILED AGAINST HIM. THE PLT (C560) SAID HE CLBED FL290 BECAUSE THAT WAS WHAT HE REQUESTED. I BELIEVE WX IN THE AREA MAY HAVE DISTR SOME. PLANES WERE ON THE W SIDE OF THE SECTOR DEVIATING. MORE ATTN TO GO THERE. I THINK THE R-SIDE DID A GOOD JOB OF TRYING TO GET THE PLANES SEPARATED ONCE THE PROB WAS KNOWN. SUPPLEMENTAL INFO FROM ACN 548759: GAVE ACFT #1 CLB TO FL280. ACFT #2 WAS AT FL290. ACFT #1 CLBED TO FL290. SUPPLEMENTAL INFO FROM ACN 548758: WE WERE CLRED TO FL270; AND REQUESTED FL290. WE WERE TOLD IT WOULD BE A FEW MINS. WE WERE TOLD FL280. WE RESPONDED FL280. IMMEDIATELY WE WERE TOLD FL290. WE RESPONDED FL290. AT ABOUT FL288; CTR TOLD US TO 'DSND; YOU WERE CLRED TO FL280; YOU HAVE TFC AT FL290.' WE SAID; 'WE THOUGHT WE WERE CLRED TO FL290; SORRY.' THEY SAID THE FL290 CALL WAS POINTING OUT TFC; NOT AN ALT FOR US TO CLB. I RPTED IT BACK AS AN ALT TO CLB TO. THE CTLRS ARE SO BUSY AND TALK SO FAST; IF NOT TOO FAST. THEIR SENTENCES AND WORDING ALL RUN TOGETHER WHEN TALKING TO ALL OF THE ACFT IN THEIR AREA. IT IS HARD TO UNDERSTAND WHO THEY ARE TALKING TO. A PLT DOES THEIR BEST TO PICK OUT THEIR CALL SIGN; AND THEIR INFO. THE ATC CTLR GETS SO BUSY; THEY SOMETIMES DO NOT CATCH IT IF A PLT READS IT BACK WRONG. CALLBACK CONVERSATION WITH RPTR ACN 548902 REVEALED THE FOLLOWING INFO: RPTR STATED HE HAD JUST ASSUMED THE RADAR ASSOCIATE POS. HE SAID THE POS WAS A LITTLE BUSY AND THAT THE BRIEFING WAS PROPERLY PERFORMED. WHILE SCANNING THE SECTOR; HE NOTICED THE HEAD-ON CONFLICT BTWN THE C560 AND THE B737. HE IMMEDIATELY TOLD THE RADAR CTLR THAT THE C560 WAS CLBING THROUGH HIS ASSIGNED ALT. HE ALSO SAW THE B737 TAKING EVASIVE ACTION.