Flight crew of small transport ambiguity misnavigated.

Attributes
ACN	139525
Time
Date	199003
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : riw
State Reference	WY
Altitude	msl bound lower : 24000 msl bound upper : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc
Operator	common carrier : air taxi
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other descent other
Route In Use	enroute other
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp pilot : cfi
Experience	flight time last 90 days : 60 flight time total : 4000 flight time type : 300
ASRS Report	139525
Person 2
Affiliation	company : air taxi
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	non adherence : clearance other spatial deviation
Independent Detector	other other : unspecified cockpit
Resolutory Action	flight crew : became reoriented
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Descending to lander, wy we had been previously cleared RNAV direct lander. Due to poor reception of the riw VOR we were proceeding direct to lander using the laramie VOR. As we neared lander and started to descend I set the coordinates for lander in the RNAV off of riw VOR and we started navigating off of riw. When we got below the clouds I realized we had been navigating directly to riw because although I had set the coordinates in the RNAV I had not switched to RNAV mode. We were in normal VOR mode and had proceeded direct to riverton about 18 NM north of lander. The only way to avoid this type of occurrence is to carefully check the mode you're in when using an RNAV for navigation.

Original NASA ASRS Text

Title: FLT CREW OF SMT AMB MISNAVIGATED.

Narrative: DESCENDING TO LANDER, WY WE HAD BEEN PREVIOUSLY CLRED RNAV DIRECT LANDER. DUE TO POOR RECEPTION OF THE RIW VOR WE WERE PROCEEDING DIRECT TO LANDER USING THE LARAMIE VOR. AS WE NEARED LANDER AND STARTED TO DSND I SET THE COORDINATES FOR LANDER IN THE RNAV OFF OF RIW VOR AND WE STARTED NAVIGATING OFF OF RIW. WHEN WE GOT BELOW THE CLOUDS I REALIZED WE HAD BEEN NAVIGATING DIRECTLY TO RIW BECAUSE ALTHOUGH I HAD SET THE COORDINATES IN THE RNAV I HAD NOT SWITCHED TO RNAV MODE. WE WERE IN NORMAL VOR MODE AND HAD PROCEEDED DIRECT TO RIVERTON ABOUT 18 NM N OF LANDER. THE ONLY WAY TO AVOID THIS TYPE OF OCCURRENCE IS TO CAREFULLY CHECK THE MODE YOU'RE IN WHEN USING AN RNAV FOR NAVIGATION.

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.