Pilot of A36 deviates from assigned course and altitude when autoplt malfunctions.

Attributes
ACN	592033
Time
Date	200308
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : hbu.vortac
State Reference	CO
Altitude	msl bound lower : 16500 msl bound upper : 17000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv.artcc tower : stl.tower
Operator	general aviation : personal
Make Model Name	Bonanza 36
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Route In Use	enroute airway : v244.airway
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 44 flight time total : 1963 flight time type : 800
ASRS Report	592033
Person 2
Affiliation	government : faa
Function	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : far other anomaly other spatial deviation
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance controller : provided flight assist
Consequence	other
Supplementary
Problem Areas	ATC Human Performance Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

While established on V244, 38 NM east of hbu VOR at 17000 ft, the autoplt malfunctioned and put the aircraft in a diving left turn. I had my head down briefing the approach plate for guc, so I didn't immediately catch the deviation from course and altitude. When I did catch it, I turned off the autoplt and initiated a recovery. During that recovery, ATC called and asked if I was proceeding direct hbu. I asked him to 'stand by' as I had my hands full. When I recovered the aircraft to a level flight attitude it was at about 16500 ft and headed south rather than west along the airway V244 to hbu. As I was turning to the northwest to reintercept the airway, and climbing back to 17000 ft, ATC called with 'proceed direct hbu, descend and maintain 16000 ft and expect holding instructions for hbu.' I proceeded as instructed, held with other aircraft at hbu, and shot a successful approach when my turn came. All of this occurred in IMC. I plan to have the autoplt checked out by an avionics shop when we return to oklahoma.

Original NASA ASRS Text

Title: PLT OF A36 DEVIATES FROM ASSIGNED COURSE AND ALT WHEN AUTOPLT MALFUNCTIONS.

Narrative: WHILE ESTABLISHED ON V244, 38 NM E OF HBU VOR AT 17000 FT, THE AUTOPLT MALFUNCTIONED AND PUT THE ACFT IN A DIVING L TURN. I HAD MY HEAD DOWN BRIEFING THE APCH PLATE FOR GUC, SO I DIDN'T IMMEDIATELY CATCH THE DEV FROM COURSE AND ALT. WHEN I DID CATCH IT, I TURNED OFF THE AUTOPLT AND INITIATED A RECOVERY. DURING THAT RECOVERY, ATC CALLED AND ASKED IF I WAS PROCEEDING DIRECT HBU. I ASKED HIM TO 'STAND BY' AS I HAD MY HANDS FULL. WHEN I RECOVERED THE ACFT TO A LEVEL FLT ATTITUDE IT WAS AT ABOUT 16500 FT AND HEADED S RATHER THAN W ALONG THE AIRWAY V244 TO HBU. AS I WAS TURNING TO THE NW TO REINTERCEPT THE AIRWAY, AND CLBING BACK TO 17000 FT, ATC CALLED WITH 'PROCEED DIRECT HBU, DSND AND MAINTAIN 16000 FT AND EXPECT HOLDING INSTRUCTIONS FOR HBU.' I PROCEEDED AS INSTRUCTED, HELD WITH OTHER ACFT AT HBU, AND SHOT A SUCCESSFUL APCH WHEN MY TURN CAME. ALL OF THIS OCCURRED IN IMC. I PLAN TO HAVE THE AUTOPLT CHKED OUT BY AN AVIONICS SHOP WHEN WE RETURN TO OKLAHOMA.

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.