A be-35 pilot on an IFR flight plan descended below his cleared altitude inbound to hln.

Attributes
ACN	1070110
Time
Date	201302
Local Time Of Day	1201-1800
Place
Locale Reference	HLN.Airport
State Reference	MT
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Bonanza 35
Operating Under FAR Part	Part 91
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Single Pilot
Qualification	Flight Crew Private Flight Crew Instrument
Experience	Flight Crew Last 90 Days 17 Flight Crew Total 585 Flight Crew Type 395
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance

Narrative:

I was coming into hln from the east on V2 at 11;000 feet MSL on an IFR flight plan. The conditions were IMC. At about 7 miles I broke out and had the airport in sight. The airport field elevation is 3;873 feet. I thought that I had clearance to descend to 9;000 feet; but that was not so.

Original NASA ASRS Text

Title: A BE-35 pilot on an IFR flight plan descended below his cleared altitude inbound to HLN.

Narrative: I was coming into HLN from the East on V2 at 11;000 feet MSL on an IFR flight plan. The conditions were IMC. At about 7 miles I broke out and had the airport in sight. The airport field elevation is 3;873 feet. I thought that I had clearance to descend to 9;000 feet; but that was not so.

Data retrieved from NASA's ASRS site as of July 2013 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.