Kingair C90 flight crew has an altitude deviation during cruise.

Attributes
ACN	699402
Time
Date	200606
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : dbn.vortac
State Reference	GA
Altitude	msl bound lower : 16000 msl bound upper : 16500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl.artcc
Operator	general aviation : corporate
Make Model Name	King Air C90 E90
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : atp pilot : cfi
Experience	flight time last 90 days : 100 flight time total : 10200 flight time type : 500
ASRS Report	699402
Person 2
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : returned to assigned altitude flight crew : overcame equipment problem
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

This aircraft is an old airplane (30 yrs old). We have constant; small; annoying problems with various system and avionics. One of the biggest; most recurring problems is with a new avidyne/nexrad installation. During the incident flight; the nexrad had again quit working. Even though the WX was clear; we started fidgeting with the nexrad receiver; out of boredom mostly. About the time the PIC and I were both occupied with troubleshooting menus; the flight director decided to teach us a lesson; and started a slow climb. At 16500 ft (while flying an assigned altitude of 16000 ft); the PIC suddenly noticed that we were off our altitude. He quickly brought us back to 16000 ft. We never received an altitude alert; nor did the autoplt disengage to cause the climb it was as if the flight director had decided that we needed to be at another altitude. This isn't the only time the flight director has given bad commands.

Original NASA ASRS Text

Title: KINGAIR C90 FLT CREW HAS AN ALTDEV DURING CRUISE.

Narrative: THIS ACFT IS AN OLD AIRPLANE (30 YRS OLD). WE HAVE CONSTANT; SMALL; ANNOYING PROBS WITH VARIOUS SYS AND AVIONICS. ONE OF THE BIGGEST; MOST RECURRING PROBS IS WITH A NEW AVIDYNE/NEXRAD INSTALLATION. DURING THE INCIDENT FLT; THE NEXRAD HAD AGAIN QUIT WORKING. EVEN THOUGH THE WX WAS CLR; WE STARTED FIDGETING WITH THE NEXRAD RECEIVER; OUT OF BOREDOM MOSTLY. ABOUT THE TIME THE PIC AND I WERE BOTH OCCUPIED WITH TROUBLESHOOTING MENUS; THE FLT DIRECTOR DECIDED TO TEACH US A LESSON; AND STARTED A SLOW CLB. AT 16500 FT (WHILE FLYING AN ASSIGNED ALT OF 16000 FT); THE PIC SUDDENLY NOTICED THAT WE WERE OFF OUR ALT. HE QUICKLY BROUGHT US BACK TO 16000 FT. WE NEVER RECEIVED AN ALT ALERT; NOR DID THE AUTOPLT DISENGAGE TO CAUSE THE CLB IT WAS AS IF THE FLT DIRECTOR HAD DECIDED THAT WE NEEDED TO BE AT ANOTHER ALT. THIS ISN'T THE ONLY TIME THE FLT DIRECTOR HAS GIVEN BAD COMMANDS.

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.