C172 pilot conducts published approach and later discovers MDA had been revised.

Attributes
ACN	737456
Time
Date	200704
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : cma.airport
State Reference	CA
Altitude	msl single value : 680
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ntd.tracon
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Navigation In Use	other vortac
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : atp
Experience	flight time last 90 days : 11 flight time total : 18020 flight time type : 930
ASRS Report	737450
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Supplementary
Problem Areas	FAA
Primary Problem	FAA

Narrative:

I filed an IFR flight plan and received a standard briefing from hawthorne FSS. I specifically asked about NOTAMS at my destination (cma); alternate (dxr) and wjf (VFR airport). My FSS briefer reported only a tethered balloon at cma (052 degree radial -- 4 mi). Approaching cma; I obtained ASOS (no ATIS as tower was late opening this date). No mention on ASOS of revised minimums for the VOR runway 26 approach. Mugu approach cleared me for the cma VOR runway 26 approach and asked me to call them on the ground on their frequency (124.7). Published MDA (with 2.1 DME) is 680 ft MSL. I completed the approach; breaking out of the clouds at 700 ft MSL and landed uneventfully. I departed cma. The tower was now open and the ATIS was reporting a revised MDA for the VOR runway 26 approach of 1100 ft MSL. If the 1100 ft MDA was in effect at the time of my approach then I obviously went well below it to the published figure of 680 ft. This is a potential violation and a serious safety issue for me. I do not know what additional steps I could have taken to get the revised MDA information.

Original NASA ASRS Text

Title: C172 PLT CONDUCTS PUBLISHED APPROACH AND LATER DISCOVERS MDA HAD BEEN REVISED.

Narrative: I FILED AN IFR FLT PLAN AND RECEIVED A STANDARD BRIEFING FROM HAWTHORNE FSS. I SPECIFICALLY ASKED ABOUT NOTAMS AT MY DEST (CMA); ALTERNATE (DXR) AND WJF (VFR ARPT). MY FSS BRIEFER RPTED ONLY A TETHERED BALLOON AT CMA (052 DEG RADIAL -- 4 MI). APCHING CMA; I OBTAINED ASOS (NO ATIS AS TWR WAS LATE OPENING THIS DATE). NO MENTION ON ASOS OF REVISED MINIMUMS FOR THE VOR RWY 26 APCH. MUGU APCH CLRED ME FOR THE CMA VOR RWY 26 APCH AND ASKED ME TO CALL THEM ON THE GND ON THEIR FREQ (124.7). PUBLISHED MDA (WITH 2.1 DME) IS 680 FT MSL. I COMPLETED THE APCH; BREAKING OUT OF THE CLOUDS AT 700 FT MSL AND LANDED UNEVENTFULLY. I DEPARTED CMA. THE TWR WAS NOW OPEN AND THE ATIS WAS RPTING A REVISED MDA FOR THE VOR RWY 26 APCH OF 1100 FT MSL. IF THE 1100 FT MDA WAS IN EFFECT AT THE TIME OF MY APCH THEN I OBVIOUSLY WENT WELL BELOW IT TO THE PUBLISHED FIGURE OF 680 FT. THIS IS A POTENTIAL VIOLATION AND A SERIOUS SAFETY ISSUE FOR ME. I DO NOT KNOW WHAT ADDITIONAL STEPS I COULD HAVE TAKEN TO GET THE REVISED MDA INFO.

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.