Small aircraft made premature descent on VOR approach due misset RNAV.

Attributes
ACN	136268
Time
Date	199002
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : rap
State Reference	SD
Altitude	msl bound lower : 3640 msl bound upper : 4300
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : rca tower : ord
Make Model Name	Small Aircraft, High Wing, 1 Eng, Retractable Gear
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Experience	flight time total : 2500
ASRS Report	136268
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	other
Consequence	faa : investigated
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While on an INS flight to rap, from minneapolis flying cloud, I experienced difficulty in completing the VOR approach. After the second missed approach the approach controller informed me I was a position nearly 5 mi further away from the VOR than my DME readout. Suddenly the lights went on! I had moved the VOR 4.6 mi up the approach radial on my RNAV for the en route segment of the flight and had not disconnected the RNAV mode for the approach. Both navigation heads showed me on course, but at MDA and the proper distance from the VOR I did not have the field in sight. I'm unfamiliar with the area and didn't recognize the obvious landmarks that would tell me I wasn't yet at the airport. I switched the RNAV mode off and completed an uneventful landing. I was greeted at the FBO's office the minute I walked in by an FAA aviation safety inspector. Someplace in my landing checklist a 'disconnect RNAV mode if appropriate' should eliminate this oversight. The RNAV light is not adequate in the daylight to trigger a response.

Original NASA ASRS Text

Title: SMA MADE PREMATURE DESCENT ON VOR APCH DUE MISSET RNAV.

Narrative: WHILE ON AN INS FLT TO RAP, FROM MINNEAPOLIS FLYING CLOUD, I EXPERIENCED DIFFICULTY IN COMPLETING THE VOR APCH. AFTER THE SECOND MISSED APCH THE APCH CTLR INFORMED ME I WAS A POS NEARLY 5 MI FURTHER AWAY FROM THE VOR THAN MY DME READOUT. SUDDENLY THE LIGHTS WENT ON! I HAD MOVED THE VOR 4.6 MI UP THE APCH RADIAL ON MY RNAV FOR THE ENRTE SEGMENT OF THE FLT AND HAD NOT DISCONNECTED THE RNAV MODE FOR THE APCH. BOTH NAV HEADS SHOWED ME ON COURSE, BUT AT MDA AND THE PROPER DISTANCE FROM THE VOR I DID NOT HAVE THE FIELD IN SIGHT. I'M UNFAMILIAR WITH THE AREA AND DIDN'T RECOGNIZE THE OBVIOUS LANDMARKS THAT WOULD TELL ME I WASN'T YET AT THE ARPT. I SWITCHED THE RNAV MODE OFF AND COMPLETED AN UNEVENTFUL LNDG. I WAS GREETED AT THE FBO'S OFFICE THE MINUTE I WALKED IN BY AN FAA AVIATION SAFETY INSPECTOR. SOMEPLACE IN MY LNDG CHKLIST A 'DISCONNECT RNAV MODE IF APPROPRIATE' SHOULD ELIMINATE THIS OVERSIGHT. THE RNAV LIGHT IS NOT ADEQUATE IN THE DAYLIGHT TO TRIGGER A RESPONSE.

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.