Flight crew of B737-300 erroneously deviates from published track on arrival to phx.

Attributes
ACN	423340
Time
Date	199812
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : iwa
State Reference	AZ
Altitude	msl bound lower : 11000 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-300
Flight Phase	descent other
Route In Use	arrival other arrival star : star
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 170 flight time total : 6500 flight time type : 2000
ASRS Report	423340
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	non adherence : published procedure non adherence : clearance other anomaly other other spatial deviation
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Air Traffic Incident	Pilot Deviation

Narrative:

I was the PNF on the last leg of a 2-DAY pairing. The captain was flying. We were cleared to cross arlin at or below 13000 ft to descend to 11000 ft and continue on the arlin one arrival to phx. So we've flown this arrival hundreds of times. We were in a B737-300 and I had verified our route in the FMC before we had left san. As we crossed arlin I wrongly assumed that the 256 degree radial off of iwa VOR was programmed in the FMC to continue the arrival. At about YC56 local time the phx approach controller asked us what our heading was. I looked at the directional gyroscope and read back 'heading 060 degrees.' I then realized that this was not the heading we were supposed to be on. The phx approach controller then asked us why we were on a 060 degree heading. The captain told him the arrival was not plugged into the box. The controller then gave us a new heading and we were on radar vectors until being cleared for a visual approach. I was wrong for not verifying our position at all times. Also, I should have had my instruments on raw data with the 256 degree radial off iwa VOR tuned in instead of 'navigation' or RNAV data. With greater vigilance I could have avoided this deviation.

Original NASA ASRS Text

Title: FLC OF B737-300 ERRONEOUSLY DEVIATES FROM PUBLISHED TRACK ON ARR TO PHX.

Narrative: I WAS THE PNF ON THE LAST LEG OF A 2-DAY PAIRING. THE CAPT WAS FLYING. WE WERE CLRED TO CROSS ARLIN AT OR BELOW 13000 FT TO DSND TO 11000 FT AND CONTINUE ON THE ARLIN ONE ARR TO PHX. SO WE'VE FLOWN THIS ARR HUNDREDS OF TIMES. WE WERE IN A B737-300 AND I HAD VERIFIED OUR RTE IN THE FMC BEFORE WE HAD LEFT SAN. AS WE CROSSED ARLIN I WRONGLY ASSUMED THAT THE 256 DEG RADIAL OFF OF IWA VOR WAS PROGRAMMED IN THE FMC TO CONTINUE THE ARR. AT ABOUT YC56 LCL TIME THE PHX APCH CTLR ASKED US WHAT OUR HEADING WAS. I LOOKED AT THE DIRECTIONAL GYROSCOPE AND READ BACK 'HDG 060 DEGS.' I THEN REALIZED THAT THIS WAS NOT THE HEADING WE WERE SUPPOSED TO BE ON. THE PHX APCH CTLR THEN ASKED US WHY WE WERE ON A 060 DEG HDG. THE CAPT TOLD HIM THE ARR WAS NOT PLUGGED INTO THE BOX. THE CTLR THEN GAVE US A NEW HEADING AND WE WERE ON RADAR VECTORS UNTIL BEING CLRED FOR A VISUAL APCH. I WAS WRONG FOR NOT VERIFYING OUR POS AT ALL TIMES. ALSO, I SHOULD HAVE HAD MY INSTS ON RAW DATA WITH THE 256 DEG RADIAL OFF IWA VOR TUNED IN INSTEAD OF 'NAV' OR RNAV DATA. WITH GREATER VIGILANCE I COULD HAVE AVOIDED THIS DEV.

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.