CE550 flight crew has a track heading deviation at FL320.

Attributes
ACN	694046
Time
Date	200604
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : llc.vortac
State Reference	NV
Altitude	msl single value : 32000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa.artcc
Operator	general aviation : corporate
Make Model Name	Citation II S2/Bravo
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial pilot : cfi pilot : atp
Experience	flight time last 90 days : 110 flight time total : 6200 flight time type : 100
ASRS Report	694046
Person 2
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Events
Anomaly	non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance controller : issued advisory flight crew : returned to original clearance
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Aircraft had a very unusual EFIS system that I never knew existed. But cruising at FL320 and everything was fine. Had questions about the EFIS; stc's and 1 item on a checklist that disagreed with another checklist in the plane so I grabbed the afm to look it up. Copilot was looking outside so I buried my attention in the book. After about 5-10 mins I looked up and it looked like the attitude indicator was showing a little 3-4 degree bank to the left. Figured I was just tired and seeing things; looked elsewhere and everything was fine so it was back into the book. After an undetermined time; probably around 1 min; ATC called and asked us if we were direct to mcc (our destination). I looked up and figured out what was going wrong; confessed to ATC and began correcting using the heading mode. We were almost 45 degrees off our course (about 240 degrees) and headed for the military airspace east of reno. The controller then mentioned this and gave us a heading of 270 degrees to keep us out. The copilot set the heading bug and we were on our way. The controller asked us for our best turn rate; so I used the turn knob on the autoplt control head; but this did not give more than about a 17 degree bank angle; so I disconnected the autoplt and set up a 30 degree turn. Shortly thereafter we were cleared direct to destination. The navigation mode was coupled to the GNS/xls and had disengaged without our knowledge. When I grabbed the autoplt turn knob it was centered as I recall. So how did we lose our navigation coupling? How did the plane get into that bank if the turn knob wasn't moved? Normally when the navigation coupling is lost; the plane will just fly wings level. I did notice that the EFIS; FMS and autoplt were from 3 different vendors and did not always do a good job of acquiring a GPS track together and required some extra attention when commanding a 'direct to.' once acquired things seemed to go well though.

Original NASA ASRS Text

Title: CE550 FLT CREW HAS A TRACK HDG DEV AT FL320.

Narrative: ACFT HAD A VERY UNUSUAL EFIS SYS THAT I NEVER KNEW EXISTED. BUT CRUISING AT FL320 AND EVERYTHING WAS FINE. HAD QUESTIONS ABOUT THE EFIS; STC'S AND 1 ITEM ON A CHKLIST THAT DISAGREED WITH ANOTHER CHKLIST IN THE PLANE SO I GRABBED THE AFM TO LOOK IT UP. COPLT WAS LOOKING OUTSIDE SO I BURIED MY ATTN IN THE BOOK. AFTER ABOUT 5-10 MINS I LOOKED UP AND IT LOOKED LIKE THE ATTITUDE INDICATOR WAS SHOWING A LITTLE 3-4 DEG BANK TO THE L. FIGURED I WAS JUST TIRED AND SEEING THINGS; LOOKED ELSEWHERE AND EVERYTHING WAS FINE SO IT WAS BACK INTO THE BOOK. AFTER AN UNDETERMINED TIME; PROBABLY AROUND 1 MIN; ATC CALLED AND ASKED US IF WE WERE DIRECT TO MCC (OUR DEST). I LOOKED UP AND FIGURED OUT WHAT WAS GOING WRONG; CONFESSED TO ATC AND BEGAN CORRECTING USING THE HDG MODE. WE WERE ALMOST 45 DEGS OFF OUR COURSE (ABOUT 240 DEGS) AND HEADED FOR THE MIL AIRSPACE E OF RENO. THE CTLR THEN MENTIONED THIS AND GAVE US A HDG OF 270 DEGS TO KEEP US OUT. THE COPLT SET THE HDG BUG AND WE WERE ON OUR WAY. THE CTLR ASKED US FOR OUR BEST TURN RATE; SO I USED THE TURN KNOB ON THE AUTOPLT CTL HEAD; BUT THIS DID NOT GIVE MORE THAN ABOUT A 17 DEG BANK ANGLE; SO I DISCONNECTED THE AUTOPLT AND SET UP A 30 DEG TURN. SHORTLY THEREAFTER WE WERE CLRED DIRECT TO DEST. THE NAV MODE WAS COUPLED TO THE GNS/XLS AND HAD DISENGAGED WITHOUT OUR KNOWLEDGE. WHEN I GRABBED THE AUTOPLT TURN KNOB IT WAS CTRED AS I RECALL. SO HOW DID WE LOSE OUR NAV COUPLING? HOW DID THE PLANE GET INTO THAT BANK IF THE TURN KNOB WASN'T MOVED? NORMALLY WHEN THE NAV COUPLING IS LOST; THE PLANE WILL JUST FLY WINGS LEVEL. I DID NOTICE THAT THE EFIS; FMS AND AUTOPLT WERE FROM 3 DIFFERENT VENDORS AND DID NOT ALWAYS DO A GOOD JOB OF ACQUIRING A GPS TRACK TOGETHER AND REQUIRED SOME EXTRA ATTN WHEN COMMANDING A 'DIRECT TO.' ONCE ACQUIRED THINGS SEEMED TO GO WELL THOUGH.

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.