A private pilot in a mooney M20 failed to maintain altitude as assigned by ATC.

Attributes
ACN	440450
Time
Date	199906
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : lnk.vortac
State Reference	NE
Altitude	msl bound lower : 4000 msl bound upper : 4350
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : lnk.tracon
Operator	general aviation : personal
Make Model Name	M-20 J (201)
Operating Under FAR Part	Part 91
Navigation In Use	other vortac
Flight Phase	cruise : level
Route In Use	enroute airway : v8.airway
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot oversight : pic
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 12 flight time total : 1434 flight time type : 1300
ASRS Report	440450
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : far non adherence : clearance
Resolutory Action	controller : provided flight assist flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Departed mle, omaha IFR and was soon assigned 4000 ft. Went through a few clouds, but mostly VFR WX. I was a bit distraction because my LORAN failed, causing me to change my routing from direct to V8 airway, and failed to notice that altitude hold was not engaged as I thought it was, and we drifted up from 4000 ft to about 4350 ft before approach or center called me on it. Prevention: keep special attention to maintaining assigned course and altitude, especially when eyes are out of cockpit watching WX and looking for reported traffic.

Original NASA ASRS Text

Title: A PVT PLT IN A MOONEY M20 FAILED TO MAINTAIN ALT AS ASSIGNED BY ATC.

Narrative: DEPARTED MLE, OMAHA IFR AND WAS SOON ASSIGNED 4000 FT. WENT THROUGH A FEW CLOUDS, BUT MOSTLY VFR WX. I WAS A BIT DISTR BECAUSE MY LORAN FAILED, CAUSING ME TO CHANGE MY ROUTING FROM DIRECT TO V8 AIRWAY, AND FAILED TO NOTICE THAT ALT HOLD WAS NOT ENGAGED AS I THOUGHT IT WAS, AND WE DRIFTED UP FROM 4000 FT TO ABOUT 4350 FT BEFORE APCH OR CTR CALLED ME ON IT. PREVENTION: KEEP SPECIAL ATTN TO MAINTAINING ASSIGNED COURSE AND ALT, ESPECIALLY WHEN EYES ARE OUT OF COCKPIT WATCHING WX AND LOOKING FOR RPTED TFC.

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.