An RV7 pilot had trouble maintaining his assigned altitude in tol airspace due to thermal activity.

Attributes
ACN	582972
Time
Date	200305
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : tol.airport
State Reference	OH
Altitude	msl single value : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : tol.tracon
Operator	general aviation : personal
Make Model Name	Experimental
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : tol.tracon
Operator	general aviation : corporate
Make Model Name	Cessna Citation Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 50 flight time total : 2000 flight time type : 50
ASRS Report	582972
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : turbulence inflight encounter other non adherence : clearance non adherence : far
Independent Detector	other controllera
Resolutory Action	controller : issued alert
Supplementary
Problem Areas	Weather Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I was entering poofe intersection into my GPS when I gained 300 ft. You would think the plane would loose altitude but I gained altitude (possible thermal). The controller had me call the tower and I was informed I made a citation take evasive action and I would be contacted by the local FSDO. A few mins after this occurred, I was advised to descend from 7000 ft to 5000 ft. I descended a couple 100 ft when the plane moved right back to 7050 ft. It was necessary to greatly reduce power in order to descend. I mentioned this because there was thermal activity in the area, and that is most likely what caused the first deviation as well.

Original NASA ASRS Text

Title: AN RV7 PLT HAD TROUBLE MAINTAINING HIS ASSIGNED ALT IN TOL AIRSPACE DUE TO THERMAL ACTIVITY.

Narrative: I WAS ENTERING POOFE INTXN INTO MY GPS WHEN I GAINED 300 FT. YOU WOULD THINK THE PLANE WOULD LOOSE ALT BUT I GAINED ALT (POSSIBLE THERMAL). THE CTLR HAD ME CALL THE TWR AND I WAS INFORMED I MADE A CITATION TAKE EVASIVE ACTION AND I WOULD BE CONTACTED BY THE LCL FSDO. A FEW MINS AFTER THIS OCCURRED, I WAS ADVISED TO DSND FROM 7000 FT TO 5000 FT. I DSNDED A COUPLE 100 FT WHEN THE PLANE MOVED RIGHT BACK TO 7050 FT. IT WAS NECESSARY TO GREATLY REDUCE PWR IN ORDER TO DSND. I MENTIONED THIS BECAUSE THERE WAS THERMAL ACTIVITY IN THE AREA, AND THAT IS MOST LIKELY WHAT CAUSED THE FIRST DEV AS WELL.

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.