B737-300 flies direct to a manually entered waypoint vice the waypoint to which cleared.

Attributes
ACN	795907
Time
Date	200807
Local Time Of Day	1201 To 1800
Place
Locale Reference	intersection : bearz
State Reference	IL
Altitude	msl bound lower : 11000 msl bound upper : 12000
Environment
Flight Conditions	VMC
Aircraft 1
Controlling Facilities	tracon : c90.tracon
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival star : n/s
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 150 flight time total : 5000 flight time type : 1100
ASRS Report	795907
Events
Anomaly	non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued advisory
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We anticipated being cleared to cross 5 mi south of bearz at 11000 ft. We built that into our routing as a waypoint between bearz and the fix prior which is boone. Before we crossed over boone; we were cleared direct bearz and cross 5 mi south at 11000 ft. We selected the 5 mi south waypoint as the point to fly to directly and the small radial difference did not become apparent until the approach controller asked us if we were proceeding direct bearz. It was then clear that we should have selected bearz as the direct point to fly to and then rebuilt the 5 mi south waypoint. It was a good lesson for us in precise navigation.

Original NASA ASRS Text

Title: B737-300 FLIES DIRECT TO A MANUALLY ENTERED WAYPOINT VICE THE WAYPOINT TO WHICH CLRED.

Narrative: WE ANTICIPATED BEING CLRED TO CROSS 5 MI S OF BEARZ AT 11000 FT. WE BUILT THAT INTO OUR ROUTING AS A WAYPOINT BTWN BEARZ AND THE FIX PRIOR WHICH IS BOONE. BEFORE WE CROSSED OVER BOONE; WE WERE CLRED DIRECT BEARZ AND CROSS 5 MI S AT 11000 FT. WE SELECTED THE 5 MI S WAYPOINT AS THE POINT TO FLY TO DIRECTLY AND THE SMALL RADIAL DIFFERENCE DID NOT BECOME APPARENT UNTIL THE APCH CTLR ASKED US IF WE WERE PROCEEDING DIRECT BEARZ. IT WAS THEN CLR THAT WE SHOULD HAVE SELECTED BEARZ AS THE DIRECT POINT TO FLY TO AND THEN REBUILT THE 5 MI S WAYPOINT. IT WAS A GOOD LESSON FOR US IN PRECISE NAV.

Data retrieved from NASA's ASRS site as of May 2009 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.