Narrative:

Our flight was cleared for takeoff from runway 9 and instructed to turn to heading 360 degrees and contact departure. Our pre-taxi clearance was to climb to 16000 ft, which is normal for our route. I checked on with departure and reported leaving 1500 ft for 16000 ft. This transmission was blocked. Departure control soon came on frequency and said 'flight xx, descend to 1500 ft immediately! Traffic 12 O'clock less than a mi at 2500 ft.' at this time we were climbing through 2000 ft and immediately began a descent. We then saw the traffic directly ahead and about 500 ft above. The controller came back on and said we were instructed to 'maintain 1500 ft for traffic.' we informed him that we received no such restr from the tower. He said he was checking with the tower. Moments later he came back to us and said the tower did tell us to maintain 1500 ft. Neither myself nor my captain could remember hearing an altitude restr, and I certainly did not read back such a restr to the tower. An accident was prevented by quick reaction from the controller. The altitude restr was never communicated to our flight crew. While the tower may have said this restr, I never read back such instructions. We feel that if such a restr was important, and this was definitely the case, the tower should have confirmed that we were aware of the restr when we failed to read it back. Runway hold short instruction are mandatory to read back, I feel it should be mandatory to read back altitude restrs and questioned by controllers when not read back.

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Original NASA ASRS Text

Title: ALTDEV. MISCOM ON ALT ASSIGNMENT BTWN TWR TRACON AND FLC. RPTR FLC CLAIMS THEY NEVER HEARD AN ALT RESTR OF 1500 FT, BUT TRACON CHKED WITH THE TWR WHO SAID THEY HAD GIVEN THE ALT RESTR TO THE FLC.

Narrative: OUR FLT WAS CLRED FOR TKOF FROM RWY 9 AND INSTRUCTED TO TURN TO HDG 360 DEGS AND CONTACT DEP. OUR PRE-TAXI CLRNC WAS TO CLB TO 16000 FT, WHICH IS NORMAL FOR OUR RTE. I CHKED ON WITH DEP AND RPTED LEAVING 1500 FT FOR 16000 FT. THIS XMISSION WAS BLOCKED. DEP CTL SOON CAME ON FREQ AND SAID 'FLT XX, DSND TO 1500 FT IMMEDIATELY! TFC 12 O'CLOCK LESS THAN A MI AT 2500 FT.' AT THIS TIME WE WERE CLBING THROUGH 2000 FT AND IMMEDIATELY BEGAN A DSCNT. WE THEN SAW THE TFC DIRECTLY AHEAD AND ABOUT 500 FT ABOVE. THE CTLR CAME BACK ON AND SAID WE WERE INSTRUCTED TO 'MAINTAIN 1500 FT FOR TFC.' WE INFORMED HIM THAT WE RECEIVED NO SUCH RESTR FROM THE TWR. HE SAID HE WAS CHKING WITH THE TWR. MOMENTS LATER HE CAME BACK TO US AND SAID THE TWR DID TELL US TO MAINTAIN 1500 FT. NEITHER MYSELF NOR MY CAPT COULD REMEMBER HEARING AN ALT RESTR, AND I CERTAINLY DID NOT READ BACK SUCH A RESTR TO THE TWR. AN ACCIDENT WAS PREVENTED BY QUICK REACTION FROM THE CTLR. THE ALT RESTR WAS NEVER COMMUNICATED TO OUR FLC. WHILE THE TWR MAY HAVE SAID THIS RESTR, I NEVER READ BACK SUCH INSTRUCTIONS. WE FEEL THAT IF SUCH A RESTR WAS IMPORTANT, AND THIS WAS DEFINITELY THE CASE, THE TWR SHOULD HAVE CONFIRMED THAT WE WERE AWARE OF THE RESTR WHEN WE FAILED TO READ IT BACK. RWY HOLD SHORT INSTRUCTION ARE MANDATORY TO READ BACK, I FEEL IT SHOULD BE MANDATORY TO READ BACK ALT RESTRS AND QUESTIONED BY CTLRS WHEN NOT READ BACK.

Data retrieved from NASA's ASRS site as of July 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.