An small aircraft private pilot flew an NDB approach improperly.

Attributes
ACN	314940
Time
Date	199509
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : plv airport : 3s2
State Reference	OR
Altitude	msl bound lower : 2500 msl bound upper : 2500
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : pdx tower : sat
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Route In Use	approach : straight in
Flight Plan	VFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 20 flight time total : 950 flight time type : 500
ASRS Report	314940
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	altitude deviation : crossing restriction not met altitude deviation : excursion from assigned altitude non adherence : published procedure non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On vectors for NDB runway 17 approach to aurdra state airport I received vector 'turn left to 280 degrees, vector to tuala, cross tuala at or above 2500 ft, cleared for the NDB approach' (tuala is a radar fix from which the approach begins). I acknowledged these instructions, turned and intercepted the 157 degree (inbound) heading to prahl. I mistakenly viewed this intercept as meaning I was over tuala (a previous approach some yrs earlier had a result of being vectored directly to tuala). I therefore started my descent immediately. A couple of mins later, approach called my position as 'over tuala.' needless to say, I had already descended below the limit of 2500 ft. I was in marginal VFR and was in no danger of colliding with terrain, but realized I had busted the limit. I had been vectored to intercept the 157 degree inbound several mi north of tuala and, due to my understanding of the vector instruction and my prior experience with vectors for this approach, I mistakenly understood my intercept to be over the fix. Identify of the radar fix using newberg VOR 70 degree radial is not very precise and is not a good substitute for radar identify.

Original NASA ASRS Text

Title: AN SMA PVT PLT FLEW AN NDB APCH IMPROPERLY.

Narrative: ON VECTORS FOR NDB RWY 17 APCH TO AURDRA STATE ARPT I RECEIVED VECTOR 'TURN L TO 280 DEGS, VECTOR TO TUALA, CROSS TUALA AT OR ABOVE 2500 FT, CLRED FOR THE NDB APCH' (TUALA IS A RADAR FIX FROM WHICH THE APCH BEGINS). I ACKNOWLEDGED THESE INSTRUCTIONS, TURNED AND INTERCEPTED THE 157 DEG (INBOUND) HDG TO PRAHL. I MISTAKENLY VIEWED THIS INTERCEPT AS MEANING I WAS OVER TUALA (A PREVIOUS APCH SOME YRS EARLIER HAD A RESULT OF BEING VECTORED DIRECTLY TO TUALA). I THEREFORE STARTED MY DSCNT IMMEDIATELY. A COUPLE OF MINS LATER, APCH CALLED MY POS AS 'OVER TUALA.' NEEDLESS TO SAY, I HAD ALREADY DSNDED BELOW THE LIMIT OF 2500 FT. I WAS IN MARGINAL VFR AND WAS IN NO DANGER OF COLLIDING WITH TERRAIN, BUT REALIZED I HAD BUSTED THE LIMIT. I HAD BEEN VECTORED TO INTERCEPT THE 157 DEG INBOUND SEVERAL MI N OF TUALA AND, DUE TO MY UNDERSTANDING OF THE VECTOR INSTRUCTION AND MY PRIOR EXPERIENCE WITH VECTORS FOR THIS APCH, I MISTAKENLY UNDERSTOOD MY INTERCEPT TO BE OVER THE FIX. IDENT OF THE RADAR FIX USING NEWBERG VOR 70 DEG RADIAL IS NOT VERY PRECISE AND IS NOT A GOOD SUBSTITUTE FOR RADAR IDENT.

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.