MD80 flight crew had a track and heading and altitude deviation while at cruise.

Attributes
ACN	718588
Time
Date	200611
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : cqy.vortac
State Reference	TX
Altitude	msl single value : 34000
Environment
Light	Night
Aircraft 1
Controlling Facilities	artcc : zfw.artcc
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	cruise : level
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	718588
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	718805
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other spatial deviation
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : returned to intended or assigned course flight crew : overcame equipment problem flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance

Narrative:

We were at cruise at FL340 with the #2 autoplt selected with the altitude mode and navigation mode selected. We were holding mach .76. Shortly after getting and entering a clearance of direct to cqy into the FMS; the aircraft began an uncommanded left descending turn. The captain and I were both in the process of setting up the approach. The aircraft descended and the altitude warning sounded. The captain took the controls and turned off the autoplt and recovered back to wings level and climbed back to altitude. We briefed ATC and the flight attendants of the event.

Original NASA ASRS Text

Title: MD80 FLT CREW HAD A TRACK AND HDG AND ALTDEV WHILE AT CRUISE.

Narrative: WE WERE AT CRUISE AT FL340 WITH THE #2 AUTOPLT SELECTED WITH THE ALT MODE AND NAV MODE SELECTED. WE WERE HOLDING MACH .76. SHORTLY AFTER GETTING AND ENTERING A CLRNC OF DIRECT TO CQY INTO THE FMS; THE ACFT BEGAN AN UNCOMMANDED L DSNDING TURN. THE CAPT AND I WERE BOTH IN THE PROCESS OF SETTING UP THE APCH. THE ACFT DSNDED AND THE ALT WARNING SOUNDED. THE CAPT TOOK THE CTLS AND TURNED OFF THE AUTOPLT AND RECOVERED BACK TO WINGS LEVEL AND CLBED BACK TO ALT. WE BRIEFED ATC AND THE FLT ATTENDANTS OF THE EVENT.

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.