B757-200 had a track deviation departing sna.

Attributes
ACN	581274
Time
Date	200305
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sna.airport
State Reference	CA
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sct.tracon
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	climbout : intermediate altitude
Route In Use	departure : other published ifr departure departure : on vectors departure sid : bckby
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	581274
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	non adherence : clearance non adherence : published procedure non adherence : far non adherence : company policies other spatial deviation
Independent Detector	atc equipment other atc equipment : radar other controllera
Resolutory Action	controller : issued new clearance
Consequence	other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance Company FAA Airport
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Heading deviation. Back bay 2 departure was selected and activated. I engaged LNAV at 400 ft and the aircraft was flown properly to the first waypoint departing runway 19L. We also had raw data displayed. Thinking the command bars would fly the 175 degree heading, I followed them, then we realized it was taking us too far left. It was taking us to the next waypoint. The box just draws a straight line instead of having a waypoint at the 5.6 DME for the turn. We realized right away of the error and started to correct back to 175 degree heading when ATC queried. We were just told to fly a 080 degree heading and continue. Nothing else was said. It would be nice to have a waypoint at the 5.6 DME turn as the next waypoint instead of the next coded waypoint. Next time, I will fly the raw data only until the turn to the next coded waypoint. Supplemental information from acn 581738: I believe the coded waypoints were idented incorrectly when ATC issued a new route at the end of the runway just before the curfew.

Original NASA ASRS Text

Title: B757-200 HAD A TRACK DEV DEPARTING SNA.

Narrative: HEADING DEV. BACK BAY 2 DEP WAS SELECTED AND ACTIVATED. I ENGAGED LNAV AT 400 FT AND THE ACFT WAS FLOWN PROPERLY TO THE FIRST WAYPOINT DEPARTING RWY 19L. WE ALSO HAD RAW DATA DISPLAYED. THINKING THE COMMAND BARS WOULD FLY THE 175 DEG HDG, I FOLLOWED THEM, THEN WE REALIZED IT WAS TAKING US TOO FAR L. IT WAS TAKING US TO THE NEXT WAYPOINT. THE BOX JUST DRAWS A STRAIGHT LINE INSTEAD OF HAVING A WAYPOINT AT THE 5.6 DME FOR THE TURN. WE REALIZED RIGHT AWAY OF THE ERROR AND STARTED TO CORRECT BACK TO 175 DEG HDG WHEN ATC QUERIED. WE WERE JUST TOLD TO FLY A 080 DEG HDG AND CONTINUE. NOTHING ELSE WAS SAID. IT WOULD BE NICE TO HAVE A WAYPOINT AT THE 5.6 DME TURN AS THE NEXT WAYPOINT INSTEAD OF THE NEXT CODED WAYPOINT. NEXT TIME, I WILL FLY THE RAW DATA ONLY UNTIL THE TURN TO THE NEXT CODED WAYPOINT. SUPPLEMENTAL INFO FROM ACN 581738: I BELIEVE THE CODED WAYPOINTS WERE IDENTED INCORRECTLY WHEN ATC ISSUED A NEW RTE AT THE END OF THE RWY JUST BEFORE THE CURFEW.

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.