Pilot fails to maintain assigned altitude in thunderstorm activity.

Attributes
ACN	317115
Time
Date	199510
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : uim
State Reference	TX
Altitude	msl bound lower : 7000 msl bound upper : 8600
Environment
Flight Conditions	IMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zfw
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Route In Use	enroute other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial pilot : cfi
Experience	flight time last 90 days : 50 flight time total : 2200 flight time type : 500
ASRS Report	317115
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather non adherence : far non adherence : clearance other anomaly other anomaly other
Independent Detector	other other : unspecified cockpit
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : exited adverse environment flight crew : regained aircraft control
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation

Narrative:

IFR near vim VOR, assigned altitude 7000 ft MSL. Entered edge of thunderstorm cell, heavy rain then vertical air current caused altitude deviation to 8600 ft MSL. Did not want to make drastic control inputs so reduced power, maintained level altitude and accepted change in airspeed and altitude. ATC inquired regarding assigned altitude and I returned to 7000 ft MSL promptly after exiting the cell. Should not have come so close to thunderstorm, even back side of a diminishing cell.

Original NASA ASRS Text

Title: PLT FAILS TO MAINTAIN ASSIGNED ALT IN TSTM ACTIVITY.

Narrative: IFR NEAR VIM VOR, ASSIGNED ALT 7000 FT MSL. ENTERED EDGE OF TSTM CELL, HVY RAIN THEN VERT AIR CURRENT CAUSED ALTDEV TO 8600 FT MSL. DID NOT WANT TO MAKE DRASTIC CTL INPUTS SO REDUCED PWR, MAINTAINED LEVEL ALT AND ACCEPTED CHANGE IN AIRSPD AND ALT. ATC INQUIRED REGARDING ASSIGNED ALT AND I RETURNED TO 7000 FT MSL PROMPTLY AFTER EXITING THE CELL. SHOULD NOT HAVE COME SO CLOSE TO TSTM, EVEN BACK SIDE OF A DIMINISHING CELL.

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.