B737-700 flight crew has a GS deviation during coupled approach to oak.

Attributes
ACN	726935
Time
Date	200702
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : oak.airport
State Reference	CA
Altitude	agl bound lower : 500 agl bound upper : 800
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : oak.tower
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 11
Flight Phase	descent : approach
Route In Use	approach : instrument precision
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 196
ASRS Report	726935
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	other anomaly
Independent Detector	aircraft equipment other aircraft equipment : glide slope indication other flight crewa other flight crewb
Resolutory Action	controller : issued advisory flight crew : overrode automation
Supplementary
Problem Areas	Navigational Facility
Primary Problem	Navigational Facility

Narrative:

On GS at approximately 800 ft AGL doing a coupled ILS; the aircraft pitched up approximately 5 degrees; autoplt disengaged; and flight director commands became unusable. GS indications stabilized in a few seconds; so we reengaged autoplt; and coupled up. At about 500 ft the tower controller stated that we can expect some ILS deviations as an aircraft departs; and sure enough we got it again. We ended up hand flying the ILS to a landing. These ILS GS deviations on runway 11 at oak are a known problem which needs to be fixed. The magnitude of the deviations is not just little 'bumps;' they are unacceptable.

Original NASA ASRS Text

Title: B737-700 FLT CREW HAS A GS DEV DURING COUPLED APCH TO OAK.

Narrative: ON GS AT APPROX 800 FT AGL DOING A COUPLED ILS; THE ACFT PITCHED UP APPROX 5 DEGS; AUTOPLT DISENGAGED; AND FLT DIRECTOR COMMANDS BECAME UNUSABLE. GS INDICATIONS STABILIZED IN A FEW SECONDS; SO WE REENGAGED AUTOPLT; AND COUPLED UP. AT ABOUT 500 FT THE TWR CTLR STATED THAT WE CAN EXPECT SOME ILS DEVS AS AN ACFT DEPARTS; AND SURE ENOUGH WE GOT IT AGAIN. WE ENDED UP HAND FLYING THE ILS TO A LNDG. THESE ILS GS DEVS ON RWY 11 AT OAK ARE A KNOWN PROB WHICH NEEDS TO BE FIXED. THE MAGNITUDE OF THE DEVS IS NOT JUST LITTLE 'BUMPS;' THEY ARE UNACCEPTABLE.

Data retrieved from NASA's ASRS site as of January 2009 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.