A corporate jet captain reported deviating from the loupe 1 SID track out of sjc when his FMC failed...

Attributes
ACN	875925
Time
Date	201002
Local Time Of Day	0601-1200
Place
Locale Reference	NCT.TRACON
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 91
Flight Phase	Takeoff
Route In Use	SID LOUPE ONE
Component
Aircraft Component	FMS/FMC
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 15 Flight Crew Total 2800 Flight Crew Type 800
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Narrative:

I had just taken off from runway 30L and was at the 1.8 NM sjc fix on the loupe one departure. The airplane's FMS was supposed to commence a right turn to a heading of 120 degrees; instead the FMS went into fail mode with all functions abruptly terminating. The airplane entered a roll mode and began a turn to the left. As I was looking down to reenter the departure I did not notice the turn. Tower then came on stating; 'turn to a heading of 120;' never saying right or left; I assume he saw me deviating to the left; and I was within a sixty degree heading of 120. I began a left turn instead of a right turn. Tower came back on and corrected the direction I was to be turning. At no time did I break an altitude restriction or have conflict with another airplane. I realize the fact I should have flown the airplane and not worried about the FMS failure. I'm sorry for the mistake; it will not happen again.

Original NASA ASRS Text

Title: A corporate jet Captain reported deviating from the Loupe 1 SID track out of SJC when his FMC failed.

Narrative: I had just taken off from Runway 30L and was at the 1.8 NM SJC fix on the LOUPE ONE Departure. The airplane's FMS was supposed to commence a right turn to a heading of 120 degrees; instead the FMS went into fail mode with all functions abruptly terminating. The airplane entered a roll mode and began a turn to the left. As I was looking down to reenter the departure I did not notice the turn. Tower then came on stating; 'turn to a heading of 120;' never saying right or left; I assume he saw me deviating to the left; and I was within a sixty degree heading of 120. I began a left turn instead of a right turn. Tower came back on and corrected the direction I was to be turning. At no time did I break an altitude restriction or have conflict with another airplane. I realize the fact I should have flown the airplane and not worried about the FMS failure. I'm sorry for the mistake; it will NOT happen again.

Data retrieved from NASA's ASRS site as of April 2012 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.