A320 captain experiences an GPWS terrain warning during visual approach to runway 28L at sfo and con...

Narrative:

We were cleared for the FMS visual 28R sfo. (We saw the airport 30 miles out) after loading the FMS visual I hard tuned the ILS frequency for 28R in my mcdu. While descending on the FMS visual we armed the approach in error prior to reaching the final approach alt. Realizing this I elected to hand fly the arrival and meet all crossing restrictions. At the FAF we were gear down flaps 3 and on speed. Inside samul sfo tower instructed us to sidestep to 28L; we complied. At 1;000 AGL we were flaps full on speed on vertical and lateral profile. At this point I was on the VASI for 28L; target speed plus 5 KTS. The pilot not flying informed me the ILS 28L was installed so I turned my flight director (FD) back on. However my FD told me to fly to 28R. I asked the pilot not flying to clear the hard tuned ILS to 28R so I might regain 28L FD info. At about 800 AGL we got a GPWS warning whoop; whoop pull up terrain pull up. I had complete confidence of our position; we were over sfo bay; short final on 28L on VASI (two red; two white) meeting all stabilized criteria; 30 miles visibility; there is no terrain 2 miles prior to 28L threshold; just bay. I knew where we were the FMGC did not. I elected to safely continue the approach and landing versus going around with a confused FMGC; landing was normal. When we parked at the gate we noticed both altimeters read -450 MSL. We have no idea how that happened both FCU altimeters were set accurately. The GPWS sounded twice when the pilot not flying removed the hard tuned 28R ILS. I had flew this aircraft on the prior leg and the FMGC failed enroute and I wrote it up; it returned to normal 5 minutes later so I canceled the write up. At first I thought we had an FMGC map shift when we got the warning until we parked and saw the altimeter error. From now on I'm not going to hard tune the ILS and correctly execute the managed approach.

Original NASA ASRS Text

Title: A320 Captain experiences an GPWS terrain warning during visual approach to Runway 28L at SFO and continues the approach to landing. The ILS 28R had been hard tuned previously and had to be changed when cleared for Runway 28L. Both altimeters read 450 feet low at the gate.

Narrative: We were cleared for the FMS Visual 28R SFO. (We saw the airport 30 miles out) after loading the FMS Visual I hard tuned the ILS frequency for 28R in my MCDU. While descending on the FMS Visual we armed the approach in error prior to reaching the final approach alt. realizing this I elected to hand fly the arrival and meet all crossing restrictions. At the FAF we were gear down flaps 3 and on speed. Inside SAMUL SFO Tower instructed us to sidestep to 28L; we complied. At 1;000 AGL we were flaps full on speed on vertical and lateral profile. At this point I was on the VASI for 28L; target speed plus 5 KTS. The pilot not flying informed me the ILS 28L was installed so I turned my Flight Director (FD) back on. However my FD told me to fly to 28R. I asked the pilot not flying to clear the hard tuned ILS to 28R so I might regain 28L FD info. At about 800 AGL we got a GPWS warning whoop; whoop pull up terrain pull up. I had complete confidence of our position; we were over SFO bay; short final on 28L on VASI (two red; two white) meeting all stabilized criteria; 30 miles visibility; there is no terrain 2 miles prior to 28L threshold; just bay. I knew where we were the FMGC did not. I elected to safely continue the approach and landing versus going around with a confused FMGC; landing was normal. When we parked at the gate we noticed both altimeters read -450 MSL. We have no idea how that happened both FCU altimeters were set accurately. The GPWS sounded twice when the pilot not flying removed the hard tuned 28R ILS. I had flew this aircraft on the prior leg and the FMGC failed enroute and I wrote it up; it returned to normal 5 minutes later so I canceled the write up. At first I thought we had an FMGC map shift when we got the warning until we parked and saw the altimeter error. From now on I'm not going to hard tune the ILS and correctly execute the managed approach.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	990998
Time
Date	201201
Local Time Of Day	0001-0600
Place
Locale Reference	SFO.Airport
State Reference	CA
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Route In Use	Visual Approach
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 180 Flight Crew Total 21000 Flight Crew Type 3200
Person 2
Function	Pilot Not Flying First Officer
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 10000 Flight Crew Type 1500
Events
Anomaly	Aircraft Equipment Problem Critical

A320 captain experiences an GPWS terrain warning during visual approach to runway 28L at sfo and continues the approach to landing. The ILS 28R had been hard tuned previously and had to be changed when cleared for runway 28L. Both altimeters read 450 feet low at the gate.