Narrative:

I was the first officer and PNF. Scheduled flight las-slc on 5/X/89. While en route the controller gave us a crossing restriction for the descent (5 mi south of fairfield VOR). A few mins later he changed the restriction to 40 south of slc VOR at 10000'. As we were a little busy in the cockpit, I took care to see correct terminology ('one-zero-thousand feet'), make a written note on a pad, and set the new altitude in the altitude alert window. The captain acknowledged the new restriction. It was dusk with good visibility. Descending through 14000', the captain mentioned that it looked 'like we are going to hit those hills,' in a joking manner. My reply was that I'm sure he would turn us right (about 45 degrees) into the downwind shortly. Passing through 12700' the controller asked us to say altitude. When I replied he said, 'stop descent, turn right (approximately 30 degrees) and climb to 13000'.' then he told us we were only cleared to 17000' 40 mi south of slc VOR. The captain then told him of our acknowledged clearance to 10000' and asked if any further action was necessary (any kind of report). The controller said there was no problem. The captain was familiar with the airport and told me that if dark or IMC he would have questioned the approach path.I have been into the airport only 2 or 3 times and in all honesty, if it was dark or IMC, I would have probably thought we were east of the hills entering a downwind to the west runways. The problem was a simply misunderstanding--'1-0-thousand' vs. '1-7-thousand.' I thought the controller said '0' and he must have thought I said '7.' no harm done this time. Just a thought: if I had replied '10-thousand, ' he probably would not have mistook it for '17-thousand.' is our phraseology outdated?

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Original NASA ASRS Text

Title: ACR WAS ISSUED A CLIMB AFTER DESCENDING BELOW ASSIGNED ALT.

Narrative: I WAS THE F/O AND PNF. SCHEDULED FLT LAS-SLC ON 5/X/89. WHILE ENRTE THE CTLR GAVE US A XING RESTRICTION FOR THE DSCNT (5 MI S OF FAIRFIELD VOR). A FEW MINS LATER HE CHANGED THE RESTRICTION TO 40 S OF SLC VOR AT 10000'. AS WE WERE A LITTLE BUSY IN THE COCKPIT, I TOOK CARE TO SEE CORRECT TERMINOLOGY ('ONE-ZERO-THOUSAND FEET'), MAKE A WRITTEN NOTE ON A PAD, AND SET THE NEW ALT IN THE ALT ALERT WINDOW. THE CAPT ACKNOWLEDGED THE NEW RESTRICTION. IT WAS DUSK WITH GOOD VISIBILITY. DSNDING THROUGH 14000', THE CAPT MENTIONED THAT IT LOOKED 'LIKE WE ARE GOING TO HIT THOSE HILLS,' IN A JOKING MANNER. MY REPLY WAS THAT I'M SURE HE WOULD TURN US RIGHT (ABOUT 45 DEGS) INTO THE DOWNWIND SHORTLY. PASSING THROUGH 12700' THE CTLR ASKED US TO SAY ALT. WHEN I REPLIED HE SAID, 'STOP DSCNT, TURN RIGHT (APPROX 30 DEGS) AND CLB TO 13000'.' THEN HE TOLD US WE WERE ONLY CLRED TO 17000' 40 MI S OF SLC VOR. THE CAPT THEN TOLD HIM OF OUR ACKNOWLEDGED CLRNC TO 10000' AND ASKED IF ANY FURTHER ACTION WAS NECESSARY (ANY KIND OF RPT). THE CTLR SAID THERE WAS NO PROB. THE CAPT WAS FAMILIAR WITH THE ARPT AND TOLD ME THAT IF DARK OR IMC HE WOULD HAVE QUESTIONED THE APCH PATH.I HAVE BEEN INTO THE ARPT ONLY 2 OR 3 TIMES AND IN ALL HONESTY, IF IT WAS DARK OR IMC, I WOULD HAVE PROBABLY THOUGHT WE WERE E OF THE HILLS ENTERING A DOWNWIND TO THE W RWYS. THE PROB WAS A SIMPLY MISUNDERSTANDING--'1-0-THOUSAND' VS. '1-7-THOUSAND.' I THOUGHT THE CTLR SAID '0' AND HE MUST HAVE THOUGHT I SAID '7.' NO HARM DONE THIS TIME. JUST A THOUGHT: IF I HAD REPLIED '10-THOUSAND, ' HE PROBABLY WOULD NOT HAVE MISTOOK IT FOR '17-THOUSAND.' IS OUR PHRASEOLOGY OUTDATED?

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.