B737 crew had track deviation.

Attributes
ACN	442440
Time
Date	199907
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : sjc.airport
State Reference	CA
Altitude	agl single value : 400
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : o90.tracon
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	climbout : initial
Route In Use	departure sid : san jose 8
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 230 flight time total : 9000 flight time type : 1000
ASRS Report	442440
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	other controllera
Resolutory Action	flight crew : returned to original clearance
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flying the new generation B737-700, the sjc 8 moony departure was in the box and show the turn to 110 degrees on the map. Upon reaching 400 ft, called for LNAV instead of heading select. SID calls for runway heading until 1.8 DME and then right turn to 110 degrees. Immediately after LNAV was selected, command bars show the turn to right. Confusion as to DME distance, I began the turn. Either tower or departure (I don't remember which) reminded us to wait until 1.8 DME to begin turn. Lesson learned is don't always believe flight guidance -- make sure you xchk with standard navaids.

Original NASA ASRS Text

Title: B737 CREW HAD TRACK DEV.

Narrative: FLYING THE NEW GENERATION B737-700, THE SJC 8 MOONY DEP WAS IN THE BOX AND SHOW THE TURN TO 110 DEGS ON THE MAP. UPON REACHING 400 FT, CALLED FOR LNAV INSTEAD OF HDG SELECT. SID CALLS FOR RWY HDG UNTIL 1.8 DME AND THEN R TURN TO 110 DEGS. IMMEDIATELY AFTER LNAV WAS SELECTED, COMMAND BARS SHOW THE TURN TO R. CONFUSION AS TO DME DISTANCE, I BEGAN THE TURN. EITHER TWR OR DEP (I DON'T REMEMBER WHICH) REMINDED US TO WAIT UNTIL 1.8 DME TO BEGIN TURN. LESSON LEARNED IS DON'T ALWAYS BELIEVE FLT GUIDANCE -- MAKE SURE YOU XCHK WITH STANDARD NAVAIDS.

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.