Narrative:

After passing through 10000' on the musel 5 departure from sna to phx and cleared to FL230 by ATC I checked off the radio with the first officer to contact company for our departure message. I came back on the radio with ZLA as we were passing approximately 14000'. After passing 15000' heading direct for thermal, ZLA called traffic out to us. I acknowledged the traffic call and informed them that we were IMC. The traffic was again called out to us as we approached 16500'. I acknowledged the traffic and stated that we were still IMC. Shortly before descent into phx I was again off of the radio taking down ATIS and passing arrival information to the company. At that time the first officer received a phone number for me to call once I arrived in phx. Reference was given to a possible altitude deviation from the last sector. Callback conversation with reporter revealed the following: reporter said that they had been cleared to climb to FL230. He went off the air to talk to company. While off the air, ATC cleared them to maintain 15000'. His first officer said he did not hear the clearance or accept it. He said that apparently someone else accepted their clearance. ATC was pointing out traffic expecting them to stop climb at 15000'. Reporter is not sure but assumes the traffic was at 16000'. The tapes have been pulled and reporter will hear the results of the investigation shortly.

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Original NASA ASRS Text

Title: MLG CLIMBED THROUGH ASSIGNED ALT CAUSING POSSIBLE LESS THAN STANDARD SEPARATION.

Narrative: AFTER PASSING THROUGH 10000' ON THE MUSEL 5 DEP FROM SNA TO PHX AND CLRED TO FL230 BY ATC I CHKED OFF THE RADIO WITH THE F/O TO CONTACT COMPANY FOR OUR DEP MESSAGE. I CAME BACK ON THE RADIO WITH ZLA AS WE WERE PASSING APPROX 14000'. AFTER PASSING 15000' HDG DIRECT FOR THERMAL, ZLA CALLED TFC OUT TO US. I ACKNOWLEDGED THE TFC CALL AND INFORMED THEM THAT WE WERE IMC. THE TFC WAS AGAIN CALLED OUT TO US AS WE APCHED 16500'. I ACKNOWLEDGED THE TFC AND STATED THAT WE WERE STILL IMC. SHORTLY BEFORE DSCNT INTO PHX I WAS AGAIN OFF OF THE RADIO TAKING DOWN ATIS AND PASSING ARR INFO TO THE COMPANY. AT THAT TIME THE F/O RECEIVED A PHONE NUMBER FOR ME TO CALL ONCE I ARRIVED IN PHX. REF WAS GIVEN TO A POSSIBLE ALT DEVIATION FROM THE LAST SECTOR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR SAID THAT THEY HAD BEEN CLRED TO CLB TO FL230. HE WENT OFF THE AIR TO TALK TO COMPANY. WHILE OFF THE AIR, ATC CLRED THEM TO MAINTAIN 15000'. HIS F/O SAID HE DID NOT HEAR THE CLRNC OR ACCEPT IT. HE SAID THAT APPARENTLY SOMEONE ELSE ACCEPTED THEIR CLRNC. ATC WAS POINTING OUT TFC EXPECTING THEM TO STOP CLB AT 15000'. RPTR IS NOT SURE BUT ASSUMES THE TFC WAS AT 16000'. THE TAPES HAVE BEEN PULLED AND RPTR WILL HEAR THE RESULTS OF THE INVESTIGATION SHORTLY.

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.