Narrative:

Inbound to sfo, assigned 11000 ft, on the FMS bridge visual runway 28R. We were cleared 'direct archi to intercept the FMS bridge visual runway 28R.' I was reviewing the arrival again and when I looked up, we were passing through 10000 ft. I asked the captain if we had been cleared out of 11000 ft and he said he thought we were cleared for the approach. I took the airplane, which was on autoplt, and started a climb toward 11000 ft. At that time ATC called and asked our assigned altitude. The captain responded that we were on the arrival profile. ATC then cleared us to maintain 8000 ft. No other discussion followed and we were subsequently cleared the arrival profile. I believe the problem was that the captain thought we were cleared for the FMS approach, when in reality were just supposed to track inbound on it at 11000 ft. I didn't notice the captain start the descent. Earlier the captain had me set 7000 ft in the altitude window -- the next altitude required at archi. Our SOP says that we only set a cleared altitude into the window. That should have clued me to the fact the captain thought we were cleared the approach, but I missed it. I think verbiage has a lot to do with what occurred. The words 'cleared to intercept the approach' and 'cleared the approach' are very similar. I understood what ATC wanted us to do, but the captain misinterped. I was not watching when the descent was initiated or I could have prevented it. If ATC had used the term 'cleared to intercept, maintain 11000 ft,' things would have been different.

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Original NASA ASRS Text

Title: CAPT OF AN LGT STARTED DSCNT EARLY DUE TO MISINTERP OF HIS CLRNC RESULTING IN ATC INTERVENTION AND CLRNC TO A LOWER ALT SO THAT HE DID NOT HAVE TO CLB BACK TO ASSIGNED.

Narrative: INBOUND TO SFO, ASSIGNED 11000 FT, ON THE FMS BRIDGE VISUAL RWY 28R. WE WERE CLRED 'DIRECT ARCHI TO INTERCEPT THE FMS BRIDGE VISUAL RWY 28R.' I WAS REVIEWING THE ARR AGAIN AND WHEN I LOOKED UP, WE WERE PASSING THROUGH 10000 FT. I ASKED THE CAPT IF WE HAD BEEN CLRED OUT OF 11000 FT AND HE SAID HE THOUGHT WE WERE CLRED FOR THE APCH. I TOOK THE AIRPLANE, WHICH WAS ON AUTOPLT, AND STARTED A CLB TOWARD 11000 FT. AT THAT TIME ATC CALLED AND ASKED OUR ASSIGNED ALT. THE CAPT RESPONDED THAT WE WERE ON THE ARR PROFILE. ATC THEN CLRED US TO MAINTAIN 8000 FT. NO OTHER DISCUSSION FOLLOWED AND WE WERE SUBSEQUENTLY CLRED THE ARR PROFILE. I BELIEVE THE PROB WAS THAT THE CAPT THOUGHT WE WERE CLRED FOR THE FMS APCH, WHEN IN REALITY WERE JUST SUPPOSED TO TRACK INBOUND ON IT AT 11000 FT. I DIDN'T NOTICE THE CAPT START THE DSCNT. EARLIER THE CAPT HAD ME SET 7000 FT IN THE ALT WINDOW -- THE NEXT ALT REQUIRED AT ARCHI. OUR SOP SAYS THAT WE ONLY SET A CLRED ALT INTO THE WINDOW. THAT SHOULD HAVE CLUED ME TO THE FACT THE CAPT THOUGHT WE WERE CLRED THE APCH, BUT I MISSED IT. I THINK VERBIAGE HAS A LOT TO DO WITH WHAT OCCURRED. THE WORDS 'CLRED TO INTERCEPT THE APCH' AND 'CLRED THE APCH' ARE VERY SIMILAR. I UNDERSTOOD WHAT ATC WANTED US TO DO, BUT THE CAPT MISINTERPED. I WAS NOT WATCHING WHEN THE DSCNT WAS INITIATED OR I COULD HAVE PREVENTED IT. IF ATC HAD USED THE TERM 'CLRED TO INTERCEPT, MAINTAIN 11000 FT,' THINGS WOULD HAVE BEEN DIFFERENT.

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.