Pilot deviated from IFR clearance when he departed from assigned altitude in ZOB airspace.

Attributes
ACN	403360
Time
Date	199805
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : eri
State Reference	PA
Altitude	msl bound lower : 10600 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : mie
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise other descent other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 25 flight time total : 650 flight time type : 125
ASRS Report	403360
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
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While talking to ZOB at 12000 ft, I requested lower. Controller asked how much lower. I responded 6000 ft. He acknowledged the request with I believe 'roger.' I took that to mean 6000 ft was approved. At 10600 ft in my descent, the controller asked what my altitude was. I responded '10600 ft descending to 6000 ft.' he said I was not cleared to 6000 ft and remain at 11000 ft. I climbed to 11000 ft and remained there until after handoff to erie approach.

Original NASA ASRS Text

Title: PLT DEVIATED FROM IFR CLRNC WHEN HE DEPARTED FROM ASSIGNED ALT IN ZOB AIRSPACE.

Narrative: WHILE TALKING TO ZOB AT 12000 FT, I REQUESTED LOWER. CTLR ASKED HOW MUCH LOWER. I RESPONDED 6000 FT. HE ACKNOWLEDGED THE REQUEST WITH I BELIEVE 'ROGER.' I TOOK THAT TO MEAN 6000 FT WAS APPROVED. AT 10600 FT IN MY DSCNT, THE CTLR ASKED WHAT MY ALT WAS. I RESPONDED '10600 FT DSNDING TO 6000 FT.' HE SAID I WAS NOT CLRED TO 6000 FT AND REMAIN AT 11000 FT. I CLBED TO 11000 FT AND REMAINED THERE UNTIL AFTER HDOF TO ERIE APCH.

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.