Narrative:

We were on right downwind for runway 28R. We were told that we were #5 for the ILS. A little later we were turned towards the runway and cleared from 6000 ft to 3000 ft. It seemed the sequence for landing had changed and, though I am not sure, some of the aircraft in front of us were switched to runway 28L. As we descended in the turn I noticed the vertical speed indicator on the pressurization system change abnormally high -- rate of 1500 FPM. I mentioned it to the captain, we determined it not to be critical and I continued to monitor it. Our speed had been reduced by ATC from an initial restr of 160 KTS to 150 KTS, a visual clearance to runway 28R was issued and accepted, and a change to tower frequency. I checked in with tower. Meanwhile, I was continuing to monitor the pressurization. I completed the before landing checks, made the standard callouts and we landed. As we touched down I had doubts about us having received a landing clearance. The runway had been clear and I don't recollect seeing anybody hold short. On clearing the runway I asked the tower for frequency change which he gave without further comment. The captain felt we had received landing clearance but couldn't remember when. I am never ambiguous about landing clrncs thus my filing this report. I did allow myself to get too absorbed with the pressurization. If we weren't cleared to land then the tower (who was no longer busy) seemed as oblivious to it as the captain was. Because I'm unsure of anything having gone wrong it's difficult to say whether there was any problem to have discovered. If there was one then the contributing factors were: ATC's sudden change of our sequence. My distraction with the pressurization. We had come off a reduced rest overnight and the captain in particular had remarked how tired he was. Usually the tower frequency is very busy and it seems to heighten one's awareness. When we were handed over to tower it wasn't busy at all. As mentioned earlier, I am normally very thorough about clrncs. I always double-check if I'm not sure. This time it crossed my mind when we touched the ground. In future, a red flag will fly any time distrs occur during normal or other procedures.

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Original NASA ASRS Text

Title: CLRNC LNDG MAY NOT HAVE BEEN RECEIVED BY COMMUTER FO. MULTIPLE RWY OP PARALLEL RWYS. SIMULTANEOUS PARALLEL APCHS IN PROGRESS.

Narrative: WE WERE ON R DOWNWIND FOR RWY 28R. WE WERE TOLD THAT WE WERE #5 FOR THE ILS. A LITTLE LATER WE WERE TURNED TOWARDS THE RWY AND CLRED FROM 6000 FT TO 3000 FT. IT SEEMED THE SEQUENCE FOR LNDG HAD CHANGED AND, THOUGH I AM NOT SURE, SOME OF THE ACFT IN FRONT OF US WERE SWITCHED TO RWY 28L. AS WE DSNDED IN THE TURN I NOTICED THE VERT SPD INDICATOR ON THE PRESSURIZATION SYS CHANGE ABNORMALLY HIGH -- RATE OF 1500 FPM. I MENTIONED IT TO THE CAPT, WE DETERMINED IT NOT TO BE CRITICAL AND I CONTINUED TO MONITOR IT. OUR SPD HAD BEEN REDUCED BY ATC FROM AN INITIAL RESTR OF 160 KTS TO 150 KTS, A VISUAL CLRNC TO RWY 28R WAS ISSUED AND ACCEPTED, AND A CHANGE TO TWR FREQ. I CHKED IN WITH TWR. MEANWHILE, I WAS CONTINUING TO MONITOR THE PRESSURIZATION. I COMPLETED THE BEFORE LNDG CHKS, MADE THE STANDARD CALLOUTS AND WE LANDED. AS WE TOUCHED DOWN I HAD DOUBTS ABOUT US HAVING RECEIVED A LNDG CLRNC. THE RWY HAD BEEN CLR AND I DON'T RECOLLECT SEEING ANYBODY HOLD SHORT. ON CLRING THE RWY I ASKED THE TWR FOR FREQ CHANGE WHICH HE GAVE WITHOUT FURTHER COMMENT. THE CAPT FELT WE HAD RECEIVED LNDG CLRNC BUT COULDN'T REMEMBER WHEN. I AM NEVER AMBIGUOUS ABOUT LNDG CLRNCS THUS MY FILING THIS RPT. I DID ALLOW MYSELF TO GET TOO ABSORBED WITH THE PRESSURIZATION. IF WE WEREN'T CLRED TO LAND THEN THE TWR (WHO WAS NO LONGER BUSY) SEEMED AS OBLIVIOUS TO IT AS THE CAPT WAS. BECAUSE I'M UNSURE OF ANYTHING HAVING GONE WRONG IT'S DIFFICULT TO SAY WHETHER THERE WAS ANY PROB TO HAVE DISCOVERED. IF THERE WAS ONE THEN THE CONTRIBUTING FACTORS WERE: ATC'S SUDDEN CHANGE OF OUR SEQUENCE. MY DISTR WITH THE PRESSURIZATION. WE HAD COME OFF A REDUCED REST OVERNIGHT AND THE CAPT IN PARTICULAR HAD REMARKED HOW TIRED HE WAS. USUALLY THE TWR FREQ IS VERY BUSY AND IT SEEMS TO HEIGHTEN ONE'S AWARENESS. WHEN WE WERE HANDED OVER TO TWR IT WASN'T BUSY AT ALL. AS MENTIONED EARLIER, I AM NORMALLY VERY THOROUGH ABOUT CLRNCS. I ALWAYS DOUBLE-CHK IF I'M NOT SURE. THIS TIME IT CROSSED MY MIND WHEN WE TOUCHED THE GND. IN FUTURE, A RED FLAG WILL FLY ANY TIME DISTRS OCCUR DURING NORMAL OR OTHER PROCS.

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.