Narrative:

Descending into low sun setting directly in our face. Could see pdx along side columbia river about 30 mi out at 8000 ft. Started descent soon after visual approach clearance issued. Approach control stated, 'cleared for visual approach to runway 28L, maintain 2000 ft until 7 NM from pdx' with the sun making it hard to see the runway and distorting distances, I was VFR but using moving map display (nd) for runway reference. The airbus 320, being a very clean aircraft, is hard to slow and descend at the same time. About 22 mi out I decided to 'scoot' on down to 2000 ft and 'motor' into the runway from there. I was descending at about 2800 FPM. At around 4000 ft we start getting 'too low terrain' GPWS and 'sink rate.' I slowed the descent slightly, but since the runway was in sight and no obvious real estate obstruction between us and the airport, we continued on down...thinking the warning was spurious. The GPWS stayed active. At about 3500 ft, I looked at the radar altimeter and it showed 1800 ft AGL. I disconnected the autoplt and returned to 4000 ft while the approach control inquired about our altitude. He assumed since we saw the runway that we would clear all terrain, but with the sun reducing visual acuity, and not looking at minimum safe altitude chart, we could have descended very very close before we became aware of the terrain.

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Original NASA ASRS Text

Title: CTLED FLT TOWARD TERRAIN IN A A-320. ALTDEV ALT OVERSHOT IN DSCNT. GPWS WARNING IGNORED. FO, PF, ATTEMPTED TO DSND LOWER THAN CLRED BECAUSE OF 'CLEAN PERFORMANCE' OF ACFT.

Narrative: DSNDING INTO LOW SUN SETTING DIRECTLY IN OUR FACE. COULD SEE PDX ALONG SIDE COLUMBIA RIVER ABOUT 30 MI OUT AT 8000 FT. STARTED DSCNT SOON AFTER VISUAL APCH CLRNC ISSUED. APCH CTL STATED, 'CLRED FOR VISUAL APCH TO RWY 28L, MAINTAIN 2000 FT UNTIL 7 NM FROM PDX' WITH THE SUN MAKING IT HARD TO SEE THE RWY AND DISTORTING DISTANCES, I WAS VFR BUT USING MOVING MAP DISPLAY (ND) FOR RWY REF. THE AIRBUS 320, BEING A VERY CLEAN ACFT, IS HARD TO SLOW AND DSND AT THE SAME TIME. ABOUT 22 MI OUT I DECIDED TO 'SCOOT' ON DOWN TO 2000 FT AND 'MOTOR' INTO THE RWY FROM THERE. I WAS DSNDING AT ABOUT 2800 FPM. AT AROUND 4000 FT WE START GETTING 'TOO LOW TERRAIN' GPWS AND 'SINK RATE.' I SLOWED THE DSCNT SLIGHTLY, BUT SINCE THE RWY WAS IN SIGHT AND NO OBVIOUS REAL ESTATE OBSTRUCTION BTWN US AND THE ARPT, WE CONTINUED ON DOWN...THINKING THE WARNING WAS SPURIOUS. THE GPWS STAYED ACTIVE. AT ABOUT 3500 FT, I LOOKED AT THE RADAR ALTIMETER AND IT SHOWED 1800 FT AGL. I DISCONNECTED THE AUTOPLT AND RETURNED TO 4000 FT WHILE THE APCH CTL INQUIRED ABOUT OUR ALT. HE ASSUMED SINCE WE SAW THE RWY THAT WE WOULD CLR ALL TERRAIN, BUT WITH THE SUN REDUCING VISUAL ACUITY, AND NOT LOOKING AT MINIMUM SAFE ALT CHART, WE COULD HAVE DSNDED VERY VERY CLOSE BEFORE WE BECAME AWARE OF THE TERRAIN.

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.