A BE1900 captain followed a flight plan as filed, rather than as what was received.

Attributes
ACN	466320
Time
Date	200003
Day	Tue
Local Time Of Day	1201 To 1800
Place
State Reference	WY
Altitude	msl single value : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv.artcc tower : ewr.tower
Operator	common carrier : air carrier
Make Model Name	Beech 1900
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 270 flight time total : 1950 flight time type : 290
ASRS Report	466320
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : commercial pilot : instrument
Events
Anomaly	non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued advisory flight crew : returned to original clearance
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

The problem arose while on an IFR flight from den to rks. We were filed from lar to ckw to ocs. We were then cleared lar direct ocs but proceeded to fly lar-ckw-ocs, as filed. Contributing factors were a lack of diligence on the captain's part in checking the clearance and a different route than we usually take to rks. We should have been more alert to possible local preferences in route selection/clearance. The problem was discovered when we were queried by ZDV as to how we were cleared when leaving den. We discovered the problem and turned approximately 10 degrees left and proceeded direct to ocs VOR. Center did not indicate that there was any problem with conflicting traffic, only that he wanted to make sure aircraft were being cleared as desired when in den. I don't think we were more than a couple mi off course at the most. To prevent a recurrence I, as captain, have begun questioning the actual wording of the clearance, before every flight, of my first officer's, who usually takes down the clearance. I make sure to do this before every flight to keep from getting complacent when receiving the same routing almost every time.

Original NASA ASRS Text

Title: A BE1900 CAPT FOLLOWED A FLT PLAN AS FILED, RATHER THAN AS WHAT WAS RECEIVED.

Narrative: THE PROB AROSE WHILE ON AN IFR FLT FROM DEN TO RKS. WE WERE FILED FROM LAR TO CKW TO OCS. WE WERE THEN CLRED LAR DIRECT OCS BUT PROCEEDED TO FLY LAR-CKW-OCS, AS FILED. CONTRIBUTING FACTORS WERE A LACK OF DILIGENCE ON THE CAPT'S PART IN CHKING THE CLRNC AND A DIFFERENT RTE THAN WE USUALLY TAKE TO RKS. WE SHOULD HAVE BEEN MORE ALERT TO POSSIBLE LCL PREFERENCES IN RTE SELECTION/CLRNC. THE PROB WAS DISCOVERED WHEN WE WERE QUERIED BY ZDV AS TO HOW WE WERE CLRED WHEN LEAVING DEN. WE DISCOVERED THE PROB AND TURNED APPROX 10 DEGS L AND PROCEEDED DIRECT TO OCS VOR. CTR DID NOT INDICATE THAT THERE WAS ANY PROB WITH CONFLICTING TFC, ONLY THAT HE WANTED TO MAKE SURE ACFT WERE BEING CLRED AS DESIRED WHEN IN DEN. I DON'T THINK WE WERE MORE THAN A COUPLE MI OFF COURSE AT THE MOST. TO PREVENT A RECURRENCE I, AS CAPT, HAVE BEGUN QUESTIONING THE ACTUAL WORDING OF THE CLRNC, BEFORE EVERY FLT, OF MY FO'S, WHO USUALLY TAKES DOWN THE CLRNC. I MAKE SURE TO DO THIS BEFORE EVERY FLT TO KEEP FROM GETTING COMPLACENT WHEN RECEIVING THE SAME ROUTING ALMOST EVERY TIME.

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.