A heavy jet on the sfo FMS bridge visual encountered severe turbulence; a 30 KT speed decrease and a...

Attributes
ACN	968865
Time
Date	201109
Local Time Of Day	1801-2400
Place
Locale Reference	NCT.TRACON
State Reference	CA
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Make Model Name	Widebody Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	Other FMS Bridge Visual
Flight Plan	IFR
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 65 Flight Crew Total 19000 Flight Crew Type 1200
Person 2
Function	Pilot Not Flying First Officer
Experience	Flight Crew Last 90 Days 150 Flight Crew Total 7000 Flight Crew Type 2000
Events
Anomaly	Deviation - Speed All Types Inflight Event / Encounter Loss Of Aircraft Control Inflight Event / Encounter Weather / Turbulence

Narrative:

We were on the FMS bridge visual to 28R in sfo. We had just passed archi at 8;000 when we were cleared for the approach. We were assigned speed 210. I had the aircraft configured flaps 5. As we were high; I elected to flch to try to catch the path. Approaching trdow I witnessed a lightning strike about a mile ahead. Weather conditions were VFR below a cloud base of about 10;000 ft. I could see the airport and the radar only indicated light rain. All of a sudden we lost 30 KTS of airspeed (180) and the vsi went 4;000 FPM down. I was hand flying so the aircraft became very heavy (out of trim) and the autothrottles responded with max power. Then the aircraft accelerated to 250 KTS while the throttles retarded to idle. My first officer retracted the flaps quickly to prevent an over speed. We lost about 2;000 ft almost instantly (which put me back on profile) we reported the windshear to ATC and continued the approach to an uneventful landing. This was the worst shear I have ever experienced in 22 years (70 KTS) and in sfo to boot. Thank god for a light aircraft with surplus power.

Original NASA ASRS Text

Title: A heavy jet on the SFO FMS Bridge Visual encountered severe turbulence; a 30 KT speed decrease and a 2;000 FT altitude loss passing the ARCHI waypoint at 8;000 FT.

Narrative: We were on the FMS bridge visual to 28R in SFO. We had just passed ARCHI at 8;000 when we were cleared for the approach. We were assigned speed 210. I had the aircraft configured flaps 5. As we were high; I elected to FLCH to try to catch the path. Approaching TRDOW I witnessed a lightning strike about a mile ahead. Weather conditions were VFR below a cloud base of about 10;000 FT. I could see the airport and the radar only indicated light rain. All of a sudden we lost 30 KTS of airspeed (180) and the VSI went 4;000 FPM down. I was hand flying so the aircraft became very heavy (out of trim) and the autothrottles responded with max power. Then the aircraft accelerated to 250 KTS while the throttles retarded to idle. My First Officer retracted the flaps quickly to prevent an over speed. We lost about 2;000 FT almost instantly (which put me back on profile) we reported the windshear to ATC and continued the approach to an uneventful landing. This was the worst shear I have ever experienced in 22 years (70 KTS) and in SFO to boot. Thank God for a light aircraft with surplus power.

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.

A heavy jet on the sfo FMS bridge visual encountered severe turbulence; a 30 KT speed decrease and a 2;000 ft altitude loss passing the archi waypoint at 8;000 ft.