Narrative:

Flying the channel 1 departure; ventura transition from sna. The route was entered correctly. I also checked the first 3 legs but don't remember looking at the following ones. After takeoff on the 175 degree heading and in a clean confign; I engaged the autoplt with LNAV engaged. We were climbing to only about 6000 ft. After awhile the autoplt turned the aircraft. The map and flight directors were centered. Shortly thereafter we noticed and ATC asked where we were going. We were going directly towards sxc on a 230 degree heading. We had not done the 200 degree heading to the 084 degree radial. ATC told us to go directly to sxc. No further comments from ATC. We checked the FMC and it showed we had channel 1 departure and the ventura transition as active. We checked and the departure in the FMC had the 200 degree heading and 084 degree radial in the legs page. The first officer said he had seen all of the legs present before the takeoff. We had not gone directly to a fix; nor closed any discontinuities. I should always compare the aircraft's actual flight path to the 10-3A page. Safety should verify that the departure will be flown correctly with the current database loaded in the aircraft fleet. Callback conversation with reporter revealed the following information: the reporter still does not know why the FMC went direct to sxc instead of following the CHANL1. Upon arrival at destination the crew loaded the route they had just flown; and all the points loaded correctly. The reporter has not been back to sna since the incident.

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Original NASA ASRS Text

Title: B737 HAS HDG DEV ON CHANL1 DEP OUT OF SNA.

Narrative: FLYING THE CHANNEL 1 DEP; VENTURA TRANSITION FROM SNA. THE RTE WAS ENTERED CORRECTLY. I ALSO CHKED THE FIRST 3 LEGS BUT DON'T REMEMBER LOOKING AT THE FOLLOWING ONES. AFTER TKOF ON THE 175 DEG HDG AND IN A CLEAN CONFIGN; I ENGAGED THE AUTOPLT WITH LNAV ENGAGED. WE WERE CLBING TO ONLY ABOUT 6000 FT. AFTER AWHILE THE AUTOPLT TURNED THE ACFT. THE MAP AND FLT DIRECTORS WERE CTRED. SHORTLY THEREAFTER WE NOTICED AND ATC ASKED WHERE WE WERE GOING. WE WERE GOING DIRECTLY TOWARDS SXC ON A 230 DEG HDG. WE HAD NOT DONE THE 200 DEG HDG TO THE 084 DEG RADIAL. ATC TOLD US TO GO DIRECTLY TO SXC. NO FURTHER COMMENTS FROM ATC. WE CHKED THE FMC AND IT SHOWED WE HAD CHANNEL 1 DEP AND THE VENTURA TRANSITION AS ACTIVE. WE CHKED AND THE DEP IN THE FMC HAD THE 200 DEG HDG AND 084 DEG RADIAL IN THE LEGS PAGE. THE FO SAID HE HAD SEEN ALL OF THE LEGS PRESENT BEFORE THE TKOF. WE HAD NOT GONE DIRECTLY TO A FIX; NOR CLOSED ANY DISCONTINUITIES. I SHOULD ALWAYS COMPARE THE ACFT'S ACTUAL FLT PATH TO THE 10-3A PAGE. SAFETY SHOULD VERIFY THAT THE DEP WILL BE FLOWN CORRECTLY WITH THE CURRENT DATABASE LOADED IN THE ACFT FLEET. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STILL DOES NOT KNOW WHY THE FMC WENT DIRECT TO SXC INSTEAD OF FOLLOWING THE CHANL1. UPON ARR AT DEST THE CREW LOADED THE RTE THEY HAD JUST FLOWN; AND ALL THE POINTS LOADED CORRECTLY. THE RPTR HAS NOT BEEN BACK TO SNA SINCE THE INCIDENT.

Data retrieved from NASA's ASRS site as of January 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.