Narrative:

Sfo utilizing soia (simultaneous offset instrument approach) procedures; ILS/prm 28L and lda/prm 28R. Soia in use due to visibility instead of overcast layer (vis 5 HZ). A B737-800 was #2 for 28L behind a heavy B747; and was going to be paired with an A319 from over cedes. I was focused on ensuring the B737-800 was in front of the A319 while still not too tight behind the B747. My trainee was monitoring me and preparing for his first soia session; only has minimal hours on finals. I was explaining to him the importance of keeping aircraft on vectors at a higher airspeed than the straight-ins to insure the 28L traffic in front by 2;100 ft. I descended the B737-800 to 4;000; I think. As I was preparing to issue the turn to final there was a loud pop in the area and an aural alarm sounded. The wiley prm had stopped working correctly and had turned off. I turned the B737-800 to a 280 heading and told him there would be a delay due to the monitor malfunction. The foster controller told me to just run the B737-800 in because he thought we could establish visual separation and issue visual approaches. Since traffic was light I elected to issue the B737-800 a left turn from a 280 heading to 030 which would take the B737-800 behind the 28R traffic. As the B737-800 was making his turn I observed him at 3;900. I issued a clearance to maintain 4;000; advised him he was outside of bravo and would re-enter at 4;000. He climbed to 4;000 and landed at sfo without any problems. The B737-800 didn't enter the 4;000 MVA but he was right on the 3;000/4;000 boundary. I don't think I missed a read back when I issued the B737-800 4000. I may have missed the B737-800 reading back 3;000 when I issued the left turn to 030. I was very focused on getting the B737-800 in front of the 28R traffic and was distracted by the monitor failure and the technicians in the area and everyone calling for a supervisor. I may have issued the B737-800 3;000 prior to the monitor going out and then forgetting about the altitude as I turned the B737-800 around. I was trying to force the B737-800 down so the foster controller wouldn't have to hold the 28R traffic to high prior to issuing the approach clearance.

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Original NASA ASRS Text

Title: NCT Controller described a possible MVA infraction during SOIA procedures when distracted by a sudden PRM failure requiring an immediate change to conventional approach procedures.

Narrative: SFO utilizing SOIA (Simultaneous Offset Instrument Approach) procedures; ILS/PRM 28L and LDA/PRM 28R. SOIA in use due to visibility instead of overcast layer (vis 5 HZ). A B737-800 was #2 for 28L behind a heavy B747; and was going to be paired with an A319 from over CEDES. I was focused on ensuring the B737-800 was in front of the A319 while still not too tight behind the B747. My trainee was monitoring me and preparing for his first SOIA session; only has minimal hours on finals. I was explaining to him the importance of keeping aircraft on vectors at a higher airspeed than the straight-ins to insure the 28L traffic in front by 2;100 FT. I descended the B737-800 to 4;000; I think. As I was preparing to issue the turn to final there was a loud pop in the area and an aural alarm sounded. The Wiley PRM had stopped working correctly and had turned off. I turned the B737-800 to a 280 heading and told him there would be a delay due to the monitor malfunction. The Foster Controller told me to just run the B737-800 in because he thought we could establish visual separation and issue visual approaches. Since traffic was light I elected to issue the B737-800 a left turn from a 280 heading to 030 which would take the B737-800 behind the 28R traffic. As the B737-800 was making his turn I observed him at 3;900. I issued a clearance to maintain 4;000; advised him he was outside of Bravo and would re-enter at 4;000. He climbed to 4;000 and landed at SFO without any problems. The B737-800 didn't enter the 4;000 MVA but he was right on the 3;000/4;000 boundary. I don't think I missed a read back when I issued the B737-800 4000. I may have missed the B737-800 reading back 3;000 when I issued the left turn to 030. I was very focused on getting the B737-800 in front of the 28R traffic and was distracted by the monitor failure and the technicians in the area and everyone calling for a Supervisor. I may have issued the B737-800 3;000 prior to the monitor going out and then forgetting about the altitude as I turned the B737-800 around. I was trying to force the B737-800 down so the FOSTER Controller wouldn't have to hold the 28R traffic to high prior to issuing the approach clearance.

Data retrieved from NASA's ASRS site as of April 2012 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.