Narrative:

Just after takeoff the captain (PF) deviated from the departure SID. The RNAV SID starts with a runway heading to the first fix at 7 DME where the first l-hand turn is. Part of the trouble the captain experienced was the dramatic aircraft differences in the 'P10' from our other aircraft. Apparently the captain had inadvertently turned the flight director off on his side and was following a full left needle bias. Normally the flight director is biased out of view when off; but apparently not in this aircraft. I was the first officer (PNF) and did not notice the early turn as we had just taken off and was busy changing the VHF radio frequency; raising the gear and selecting a snapshot of the engine display. Once I noticed we were in a turn; we were already 35 degrees off track and diverging. I immediately began to turn us back towards the SID and requested radar vectors back to the proper fix while we evaluated the captain's navigation trouble and I found his flight director switched off. The old classic instruments were a contributing factor as any FMS or moving map or GPS display would have prevented the early turn.

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Original NASA ASRS Text

Title: CONFUSED BY NONSTANDARD AVIONICS DISPLAY AND OP; CAPT OF B747-200 FAILS TO COMPLY WITH RNAV SID FROM RKSI.

Narrative: JUST AFTER TKOF THE CAPT (PF) DEVIATED FROM THE DEP SID. THE RNAV SID STARTS WITH A RWY HDG TO THE FIRST FIX AT 7 DME WHERE THE FIRST L-HAND TURN IS. PART OF THE TROUBLE THE CAPT EXPERIENCED WAS THE DRAMATIC ACFT DIFFERENCES IN THE 'P10' FROM OUR OTHER ACFT. APPARENTLY THE CAPT HAD INADVERTENTLY TURNED THE FLT DIRECTOR OFF ON HIS SIDE AND WAS FOLLOWING A FULL L NEEDLE BIAS. NORMALLY THE FLT DIRECTOR IS BIASED OUT OF VIEW WHEN OFF; BUT APPARENTLY NOT IN THIS ACFT. I WAS THE FO (PNF) AND DID NOT NOTICE THE EARLY TURN AS WE HAD JUST TAKEN OFF AND WAS BUSY CHANGING THE VHF RADIO FREQ; RAISING THE GEAR AND SELECTING A SNAPSHOT OF THE ENG DISPLAY. ONCE I NOTICED WE WERE IN A TURN; WE WERE ALREADY 35 DEGS OFF TRACK AND DIVERGING. I IMMEDIATELY BEGAN TO TURN US BACK TOWARDS THE SID AND REQUESTED RADAR VECTORS BACK TO THE PROPER FIX WHILE WE EVALUATED THE CAPT'S NAV TROUBLE AND I FOUND HIS FLT DIRECTOR SWITCHED OFF. THE OLD CLASSIC INSTS WERE A CONTRIBUTING FACTOR AS ANY FMS OR MOVING MAP OR GPS DISPLAY WOULD HAVE PREVENTED THE EARLY TURN.

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.