Aircraft failed to maintain assigned altitude.

Attributes
ACN	429074
Time
Date	199902
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : eca.vortac
State Reference	CA
Altitude	msl bound lower : 11200
Environment
Flight Conditions	Mixed
Weather Elements	Ice
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zoa.artcc
Operator	general aviation : personal
Make Model Name	PA-34-220T Turbo Seneca III
Operating Under FAR Part	Part 91
Navigation In Use	other vortac
Flight Phase	cruise : enroute altitude change
Route In Use	enroute : on vectors
Flight Plan	IFR Combined VFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : atp pilot : instrument pilot : multi engine pilot : private
Experience	flight time last 90 days : 60 flight time total : 1950 flight time type : 1400
ASRS Report	429074
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	altitude deviation : overshoot inflight encounter : weather non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to assigned airspace
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I was cleared from 14500 ft (VFR on top) to 12000 ft (IFR) with vectors to eca VOR. As I descended to 12000 ft in IMC, I started to pick up ice. I was focused on the ice buildup on the wings for the proper time to inflate the boots. I missed 12000 ft and descended to about 11200 ft. The week before, the boots didn't knock the ice off as much as I had expected and this time I wanted to hit the boots as early as appropriate, but not too early. I concentrated on the ice problem, ignoring my altitude.

Original NASA ASRS Text

Title: ACFT FAILED TO MAINTAIN ASSIGNED ALT.

Narrative: I WAS CLRED FROM 14500 FT (VFR ON TOP) TO 12000 FT (IFR) WITH VECTORS TO ECA VOR. AS I DSNDED TO 12000 FT IN IMC, I STARTED TO PICK UP ICE. I WAS FOCUSED ON THE ICE BUILDUP ON THE WINGS FOR THE PROPER TIME TO INFLATE THE BOOTS. I MISSED 12000 FT AND DSNDED TO ABOUT 11200 FT. THE WK BEFORE, THE BOOTS DIDN'T KNOCK THE ICE OFF AS MUCH AS I HAD EXPECTED AND THIS TIME I WANTED TO HIT THE BOOTS AS EARLY AS APPROPRIATE, BUT NOT TOO EARLY. I CONCENTRATED ON THE ICE PROB, IGNORING MY ALT.

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.