M209P pilot descended to the MDA outside the LOM on the NDB runway 3 approach at sat.

Attributes
ACN	594195
Time
Date	200309
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : sat.vortac
State Reference	TX
Altitude	agl bound lower : 594 agl bound upper : 1414
Environment
Flight Conditions	Marginal
Weather Elements	Rain Fog
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sat.tracon
Operator	general aviation : personal
Make Model Name	M-20 B/C Ranger
Operating Under FAR Part	Part 91
Navigation In Use	other ndb
Flight Phase	descent : approach descent : intermediate altitude
Route In Use	approach : instrument non precision
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial pilot : cfi pilot : multi engine
Experience	flight time last 90 days : 40 flight time total : 1630 flight time type : 800
ASRS Report	594195
Person 2
Affiliation	other
Function	observation : observer observation : passenger other personnel other
Events
Anomaly	altitude deviation : excursion from assigned altitude altitude deviation : overshoot inflight encounter : weather non adherence : clearance non adherence : far non adherence : published procedure other anomaly other
Independent Detector	atc equipment : msaw other controllera
Resolutory Action	controller : issued alert flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance Navigational Facility
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

About the time that we departed ssf field on the second missed, sat, ATC announced that the ILS to runway 3 was inoperative and the approach in use would be the NDB to runway 3. I received vectors to the approach course, cleared for the approach, and began a descent from 2500 ft. Here is where I screwed up royal: continued a descent right on down to 1380 ft, which is authorized only after passing the sa (bluie) NDB. Was notified by ATC of the minimum altitude up to the NDB (2200 ft). Climbed, up to this altitude and continued the approach, final to a low pass runway 3, and a left turn out to T94. I think this excursion from altitude occurred due to: lack of familiarity with this approach, coupled with a dose of surprise that we would be doing it for real at this airport (sat). Marginal VFR WX (which along with the presence of the safety pilot seduced me into forgetting that I was on a 'local IFR' flight plan). Thorough familiarity with the terrain along this segment of the approach, which I have flown VFR many times. In the light rain, slight haze, and 2000 ft ceiling, and attending mostly to the instruments, the ground did not seem overly close. I was cleared for the approach, and all seemed well. This speaks to a phenomenon with which I have had some similar experience before, but can only be expressed thusly: when your friendly home field experiences a major outage of navigation facilities, you are dealing with a whole new and now unfamiliar airport. Wow.

Original NASA ASRS Text

Title: M209P PLT DSNDED TO THE MDA OUTSIDE THE LOM ON THE NDB RWY 3 APCH AT SAT.

Narrative: ABOUT THE TIME THAT WE DEPARTED SSF FIELD ON THE SECOND MISSED, SAT, ATC ANNOUNCED THAT THE ILS TO RWY 3 WAS INOP AND THE APCH IN USE WOULD BE THE NDB TO RWY 3. I RECEIVED VECTORS TO THE APCH COURSE, CLRED FOR THE APCH, AND BEGAN A DSCNT FROM 2500 FT. HERE IS WHERE I SCREWED UP ROYAL: CONTINUED A DSCNT RIGHT ON DOWN TO 1380 FT, WHICH IS AUTHORIZED ONLY AFTER PASSING THE SA (BLUIE) NDB. WAS NOTIFIED BY ATC OF THE MINIMUM ALT UP TO THE NDB (2200 FT). CLBED, UP TO THIS ALT AND CONTINUED THE APCH, FINAL TO A LOW PASS RWY 3, AND A L TURN OUT TO T94. I THINK THIS EXCURSION FROM ALT OCCURRED DUE TO: LACK OF FAMILIARITY WITH THIS APCH, COUPLED WITH A DOSE OF SURPRISE THAT WE WOULD BE DOING IT FOR REAL AT THIS ARPT (SAT). MARGINAL VFR WX (WHICH ALONG WITH THE PRESENCE OF THE SAFETY PLT SEDUCED ME INTO FORGETTING THAT I WAS ON A 'LCL IFR' FLT PLAN). THOROUGH FAMILIARITY WITH THE TERRAIN ALONG THIS SEGMENT OF THE APCH, WHICH I HAVE FLOWN VFR MANY TIMES. IN THE LIGHT RAIN, SLIGHT HAZE, AND 2000 FT CEILING, AND ATTENDING MOSTLY TO THE INSTS, THE GND DID NOT SEEM OVERLY CLOSE. I WAS CLRED FOR THE APCH, AND ALL SEEMED WELL. THIS SPEAKS TO A PHENOMENON WITH WHICH I HAVE HAD SOME SIMILAR EXPERIENCE BEFORE, BUT CAN ONLY BE EXPRESSED THUSLY: WHEN YOUR FRIENDLY HOME FIELD EXPERIENCES A MAJOR OUTAGE OF NAV FACILITIES, YOU ARE DEALING WITH A WHOLE NEW AND NOW UNFAMILIAR ARPT. WOW.

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.