Narrative:

Scheduled air carrier flight was en route to san from lax. At approximately 25 NM from mzb (117.8) clearance was received while aircraft was level at 10000'/250 KIAS to 'descend and maintain 7000'.' the clearance to 'descend and maintain 7000'' was acknowledged by the captain and read back with call sign. PF (myself) acknowledged clearance and set 7000' on the flight guidance system and began descent. While in the descent and passing approximately 9000' a twin commuter type aircraft was observed by the captain at his 10 O'clock position at a distance estimated at 6-7 mi. The twin appeared to be 2000-3000' lower altitude and roughly on a parallel or slightly converging course. As descent continued on our part, the commuter came more clearly into my view from my seat on the right side. It was apparent that our aircraft would pass well ahead of the commuter, though as our aircraft was passing approximately 7300' to level at 7000' I remarked to the captain: 'I wonder what his altitude is? He must be at 6,' meaning 6000' and knowing that our assigned altitude was 7000'. As we were leveling at 7000' the controller came on and said that we had 'traffic at 6900'' and that we had been assigned 8000'. The captain corrected the controller, reaffirming that we had been issued a clearance to 7000' and that 'he'd better pull the tapes.' upon landing, a phone conversation ensued with the approach control supervisor to ensure that the tape would be reviewed. This morning (12/fri), I was contacted by the captain who said that our chief pilot had been contacted, and that after reviewing the tape we had been vindicated and the controller had been in error. My impression is that the controller had forgotten about the commuter aircraft.

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Original NASA ASRS Text

Title: APCH CTLR DESCENDED AN MLG TO SAME ALT AS SAME DIRECTION SMT TRAFFIC, LESS THAN STANDARD SEPARATION.

Narrative: SCHEDULED ACR FLT WAS ENRTE TO SAN FROM LAX. AT APPROX 25 NM FROM MZB (117.8) CLRNC WAS RECEIVED WHILE ACFT WAS LEVEL AT 10000'/250 KIAS TO 'DSND AND MAINTAIN 7000'.' THE CLRNC TO 'DSND AND MAINTAIN 7000'' WAS ACKNOWLEDGED BY THE CAPT AND READ BACK WITH CALL SIGN. PF (MYSELF) ACKNOWLEDGED CLRNC AND SET 7000' ON THE FLT GUIDANCE SYS AND BEGAN DSCNT. WHILE IN THE DSCNT AND PASSING APPROX 9000' A TWIN COMMUTER TYPE ACFT WAS OBSERVED BY THE CAPT AT HIS 10 O'CLOCK POS AT A DISTANCE ESTIMATED AT 6-7 MI. THE TWIN APPEARED TO BE 2000-3000' LOWER ALT AND ROUGHLY ON A PARALLEL OR SLIGHTLY CONVERGING COURSE. AS DSCNT CONTINUED ON OUR PART, THE COMMUTER CAME MORE CLEARLY INTO MY VIEW FROM MY SEAT ON THE RIGHT SIDE. IT WAS APPARENT THAT OUR ACFT WOULD PASS WELL AHEAD OF THE COMMUTER, THOUGH AS OUR ACFT WAS PASSING APPROX 7300' TO LEVEL AT 7000' I REMARKED TO THE CAPT: 'I WONDER WHAT HIS ALT IS? HE MUST BE AT 6,' MEANING 6000' AND KNOWING THAT OUR ASSIGNED ALT WAS 7000'. AS WE WERE LEVELING AT 7000' THE CTLR CAME ON AND SAID THAT WE HAD 'TFC AT 6900'' AND THAT WE HAD BEEN ASSIGNED 8000'. THE CAPT CORRECTED THE CTLR, REAFFIRMING THAT WE HAD BEEN ISSUED A CLRNC TO 7000' AND THAT 'HE'D BETTER PULL THE TAPES.' UPON LNDG, A PHONE CONVERSATION ENSUED WITH THE APCH CTL SUPVR TO ENSURE THAT THE TAPE WOULD BE REVIEWED. THIS MORNING (12/FRI), I WAS CONTACTED BY THE CAPT WHO SAID THAT OUR CHIEF PLT HAD BEEN CONTACTED, AND THAT AFTER REVIEWING THE TAPE WE HAD BEEN VINDICATED AND THE CTLR HAD BEEN IN ERROR. MY IMPRESSION IS THAT THE CTLR HAD FORGOTTEN ABOUT THE COMMUTER ACFT.

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.