Narrative:

ATIS B changed to ATIS C about 2-3 mins prior to landing. Bay approach tried to persuade us to accept a quiet bridge visual approach to runway 28R about 6-8 mins before landing with a broken cloud condition on the ATIS. Due to the cloud cover, although we could see the runways, I was not sure we could follow the altitudes on the visual approach or stay VFR, so I did not accept the visual until 3-4 mins out. Approach gave us traffic at 3 O'clock, unknown altitude, outside the marker, and also at 7 O'clock for 28L. He would stay clear of us. We were looking for traffic and transiting from sfo 090 degree radial to the sfo 28R ILS localizer, and about 1400 ft entered a scattered layer. I had not realized we would penetrate. I could see sideways and down, but from 1400 to 800 ft MSL, I could not see the runways and we were centered on the 28R localizer. Just prior to entering the cloud, I saw our 7 O'clock, about 8 O'clock, 100 ft or so behind our tail. Our TCASII said the medium large transport was 200 ft above us. After we dropped our gear and contacted the tower, I looked back and could no longer see the medium large transport on the 5 mi TCASII scale, the presentation indicated the medium large transport was about 1/8' behind our aircraft cross on the scope and 100 ft above us. Not surprisingly, we got an RA to descend more rapidly at 1200 ft MSL, which we did do. During the approach we flew assigned speeds to the marker, and we did go below the GS inside the marker due to the RA instruction. I initially considered a missed approach when we went IFR, but due to the proximity of the medium large transport, I feared executing a go around could have resulted in a collision. I don't see how the medium large transport could have kept us in sight. I assume penetrating cloud was as much a surprise to them as it was to us. I spoke to the bay approach supervisor on duty, and said we rely upon and should be assured of a reasonably accurate terminal observation. His response was bay approach does not make the observation. Approach control cannot see out on final approach. I understand his comments, but someone should be responsible for the safety aspects of the observation. I reminded him I did not have to accept a visual even in very good WX and would be much more cautious in the future about believing them. He acknowledged we had a very dangerous potential and said it would be discussed in a staff meeting. My company's manager on duty was disturbed about the incident and stated it would be reviewed with sfo approach. A last comment - the radio frequency congestion was so bad we could not make a radio transmission during the period from 1400 ft down to 700 ft.

Google
 

Original NASA ASRS Text

Title: FLC OF WDB ACCEPTED A QUIET BRIDGE APCH AT SFO AND ENCOUNTERED IMC ON DSCNT LOSING SIGHT OF TFC BEHIND AND BELOW THAT CAME IN CLOSE PROX.

Narrative: ATIS B CHANGED TO ATIS C ABOUT 2-3 MINS PRIOR TO LNDG. BAY APCH TRIED TO PERSUADE US TO ACCEPT A QUIET BRIDGE VISUAL APCH TO RWY 28R ABOUT 6-8 MINS BEFORE LNDG WITH A BROKEN CLOUD CONDITION ON THE ATIS. DUE TO THE CLOUD COVER, ALTHOUGH WE COULD SEE THE RWYS, I WAS NOT SURE WE COULD FOLLOW THE ALTS ON THE VISUAL APCH OR STAY VFR, SO I DID NOT ACCEPT THE VISUAL UNTIL 3-4 MINS OUT. APCH GAVE US TFC AT 3 O'CLOCK, UNKNOWN ALT, OUTSIDE THE MARKER, AND ALSO AT 7 O'CLOCK FOR 28L. HE WOULD STAY CLR OF US. WE WERE LOOKING FOR TFC AND TRANSITING FROM SFO 090 DEG RADIAL TO THE SFO 28R ILS LOC, AND ABOUT 1400 FT ENTERED A SCATTERED LAYER. I HAD NOT REALIZED WE WOULD PENETRATE. I COULD SEE SIDEWAYS AND DOWN, BUT FROM 1400 TO 800 FT MSL, I COULD NOT SEE THE RWYS AND WE WERE CENTERED ON THE 28R LOC. JUST PRIOR TO ENTERING THE CLOUD, I SAW OUR 7 O'CLOCK, ABOUT 8 O'CLOCK, 100 FT OR SO BEHIND OUR TAIL. OUR TCASII SAID THE MLG WAS 200 FT ABOVE US. AFTER WE DROPPED OUR GEAR AND CONTACTED THE TWR, I LOOKED BACK AND COULD NO LONGER SEE THE MLG ON THE 5 MI TCASII SCALE, THE PRESENTATION INDICATED THE MLG WAS ABOUT 1/8' BEHIND OUR ACFT CROSS ON THE SCOPE AND 100 FT ABOVE US. NOT SURPRISINGLY, WE GOT AN RA TO DSND MORE RAPIDLY AT 1200 FT MSL, WHICH WE DID DO. DURING THE APCH WE FLEW ASSIGNED SPDS TO THE MARKER, AND WE DID GO BELOW THE GS INSIDE THE MARKER DUE TO THE RA INSTRUCTION. I INITIALLY CONSIDERED A MISSED APCH WHEN WE WENT IFR, BUT DUE TO THE PROX OF THE MLG, I FEARED EXECUTING A GAR COULD HAVE RESULTED IN A COLLISION. I DON'T SEE HOW THE MLG COULD HAVE KEPT US IN SIGHT. I ASSUME PENETRATING CLOUD WAS AS MUCH A SURPRISE TO THEM AS IT WAS TO US. I SPOKE TO THE BAY APCH SUPVR ON DUTY, AND SAID WE RELY UPON AND SHOULD BE ASSURED OF A REASONABLY ACCURATE TERMINAL OBSERVATION. HIS RESPONSE WAS BAY APCH DOES NOT MAKE THE OBSERVATION. APCH CTL CANNOT SEE OUT ON FINAL APCH. I UNDERSTAND HIS COMMENTS, BUT SOMEONE SHOULD BE RESPONSIBLE FOR THE SAFETY ASPECTS OF THE OBSERVATION. I REMINDED HIM I DID NOT HAVE TO ACCEPT A VISUAL EVEN IN VERY GOOD WX AND WOULD BE MUCH MORE CAUTIOUS IN THE FUTURE ABOUT BELIEVING THEM. HE ACKNOWLEDGED WE HAD A VERY DANGEROUS POTENTIAL AND SAID IT WOULD BE DISCUSSED IN A STAFF MEETING. MY COMPANY'S MGR ON DUTY WAS DISTURBED ABOUT THE INCIDENT AND STATED IT WOULD BE REVIEWED WITH SFO APCH. A LAST COMMENT - THE RADIO FREQ CONGESTION WAS SO BAD WE COULD NOT MAKE A RADIO XMISSION DURING THE PERIOD FROM 1400 FT DOWN TO 700 FT.

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.