A BE58 pilot misunderstood altitude assigned by hou TRACON.

Attributes
ACN	434910
Time
Date	199904
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : hou.airport
State Reference	TX
Altitude	msl single value : 5500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : i90.tracon
Operator	general aviation : personal
Make Model Name	Baron 58/58TC
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude
Route In Use	departure : on vectors
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : atp pilot : cfi pilot : instrument pilot : multi engine
Experience	flight time last 90 days : 68 flight time total : 11000 flight time type : 1500
ASRS Report	434910
Person 2
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	other controllera
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:

Departing houston hobby IFR, talking to hou departure, the controller asked me to turn to heading of 270 degrees and climb to 5500 ft. I did same. He later called and asked what my altitude was. I said 5500 ft. He said he assigned me 5000 ft.

Original NASA ASRS Text

Title: A BE58 PLT MISUNDERSTOOD ALT ASSIGNED BY HOU TRACON.

Narrative: DEPARTING HOUSTON HOBBY IFR, TALKING TO HOU DEP, THE CTLR ASKED ME TO TURN TO HDG OF 270 DEGS AND CLB TO 5500 FT. I DID SAME. HE LATER CALLED AND ASKED WHAT MY ALT WAS. I SAID 5500 FT. HE SAID HE ASSIGNED ME 5000 FT.

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.