Autoplt on heading hold on climb commences uncommanded right turn 15 degrees before stopped.

Attributes
ACN	302628
Time
Date	199504
Day	Sat
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : mem
State Reference	TN
Altitude	agl bound lower : 1000 agl bound upper : 1000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tower : mem
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	climbout : initial climbout : takeoff
Route In Use	departure other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 80 flight time total : 8500 flight time type : 80
ASRS Report	302628
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe non adherence : clearance non adherence : published procedure other anomaly other other spatial deviation
Independent Detector	other flight crewa other other : unspecified cockpit
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

On takeoff from runway 36L at mem, with clearance of runway heading to 5000 ft and flight director FMS system programmed to fly in heading select, the aircraft made an uncommanded right turn at 1000 ft AGL when the autoplt was engaged. By the time autoplt was disengaged and correction back on course was beginning we were approximately 15 degrees off runway heading. The flight director and autoplts were reengaged at 1500 ft AGL and everything worked fine. I believe the aircraft sensed that it was a couple of degrees off course at autoplt engagement and, instead of turning left to runway heading, it was going to turn right 360 degrees to runway heading.

Original NASA ASRS Text

Title: AUTOPLT ON HDG HOLD ON CLB COMMENCES UNCOMMANDED R TURN 15 DEGS BEFORE STOPPED.

Narrative: ON TKOF FROM RWY 36L AT MEM, WITH CLRNC OF RWY HDG TO 5000 FT AND FLT DIRECTOR FMS SYS PROGRAMMED TO FLY IN HDG SELECT, THE ACFT MADE AN UNCOMMANDED R TURN AT 1000 FT AGL WHEN THE AUTOPLT WAS ENGAGED. BY THE TIME AUTOPLT WAS DISENGAGED AND CORRECTION BACK ON COURSE WAS BEGINNING WE WERE APPROX 15 DEGS OFF RWY HDG. THE FLT DIRECTOR AND AUTOPLTS WERE REENGAGED AT 1500 FT AGL AND EVERYTHING WORKED FINE. I BELIEVE THE ACFT SENSED THAT IT WAS A COUPLE OF DEGS OFF COURSE AT AUTOPLT ENGAGEMENT AND, INSTEAD OF TURNING L TO RWY HDG, IT WAS GOING TO TURN R 360 DEGS TO RWY HDG.

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.