Small aircraft dropped below glide slope during ILS approach. Got low altitude alert.

Attributes
ACN	143781
Time
Date	199004
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : vny
State Reference	CA
Altitude	agl bound lower : 800 agl bound upper : 800
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : vny tower : apa
Operator	general aviation : personal
Make Model Name	Small Aircraft
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 130 flight time total : 8000 flight time type : 10
ASRS Report	143781
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical non adherence : published procedure non adherence : clearance other spatial deviation
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

During ILS approach to vny 16R tower advised of a low altitude alert, just as I was breaking out of the clouds. I scanned everything only to find an off flag on the glide slope. I leveled off and only began descent when the runway and VASI became visible. There was much turbulence and rain and I never noticed the problem. I landed uneventfully. The next time it appears I am flying a perfect ILS glide slope in rain and turbulence, I will start looking around.

Original NASA ASRS Text

Title: SMA DROPPED BELOW GLIDE SLOPE DURING ILS APCH. GOT LOW ALT ALERT.

Narrative: DURING ILS APCH TO VNY 16R TWR ADVISED OF A LOW ALT ALERT, JUST AS I WAS BREAKING OUT OF THE CLOUDS. I SCANNED EVERYTHING ONLY TO FIND AN OFF FLAG ON THE GLIDE SLOPE. I LEVELED OFF AND ONLY BEGAN DSNT WHEN THE RWY AND VASI BECAME VISIBLE. THERE WAS MUCH TURBULENCE AND RAIN AND I NEVER NOTICED THE PROBLEM. I LANDED UNEVENTFULLY. THE NEXT TIME IT APPEARS I AM FLYING A PERFECT ILS GLIDE SLOPE IN RAIN AND TURBULENCE, I WILL START LOOKING AROUND.

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.