Small aircraft pilot mishears clearance, descends below assigned.

Attributes
ACN	239742
Time
Date	199304
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : srq
State Reference	FL
Altitude	msl bound lower : 1700 msl bound upper : 2100
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : tpa
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 16 flight time total : 1300 flight time type : 1100
ASRS Report	239742
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other spatial deviation
Independent Detector	other controllera other other : unspecified cockpit
Resolutory Action	controller : issued new clearance flight crew : became reoriented
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I called tampa approach and told them I was about 20 mi southeast of sarasota at 2500 ft, landing with ATIS. After giving me a code to squawk and identing me, tampa told me to turn 10 degrees right to 340 degrees and remain at or above 1200 ft. I thought this was unusual since there is an 1800 ft tower in the area and it seemed I was being vectored toward it. I fudged a little on the heading (330 degrees) to stay away from the tower and started a descent to 1200 ft. Tampa instructed me to turn to 340 degrees and a short while later asked my altitude. I replied that I was at 1700 ft whereupon tampa told me the assigned altitude was 2100 ft, not 1200 ft. I asked tampa what they wanted me to do, but their answer was unclr. They were quite busy. I started a climb to 2100 ft, at 1800 ft tampa told me to climb to 2100 ft immediately and I complied. The remainder of the flight was normal and I made an uneventful landing at sarasota. Perhaps I heard wrong, perhaps tampa made a mistake, only the tape can tell. Human error persists however I would have known what the controller had wanted me to do, climb to 2100 ft, if he had said so instead of just informing me that the assigned altitude was 2100 ft.

Original NASA ASRS Text

Title: SMA PLT MISHEARS CLRNC, DSNDS BELOW ASSIGNED.

Narrative: I CALLED TAMPA APCH AND TOLD THEM I WAS ABOUT 20 MI SE OF SARASOTA AT 2500 FT, LNDG WITH ATIS. AFTER GIVING ME A CODE TO SQUAWK AND IDENTING ME, TAMPA TOLD ME TO TURN 10 DEGS R TO 340 DEGS AND REMAIN AT OR ABOVE 1200 FT. I THOUGHT THIS WAS UNUSUAL SINCE THERE IS AN 1800 FT TWR IN THE AREA AND IT SEEMED I WAS BEING VECTORED TOWARD IT. I FUDGED A LITTLE ON THE HDG (330 DEGS) TO STAY AWAY FROM THE TWR AND STARTED A DSCNT TO 1200 FT. TAMPA INSTRUCTED ME TO TURN TO 340 DEGS AND A SHORT WHILE LATER ASKED MY ALT. I REPLIED THAT I WAS AT 1700 FT WHEREUPON TAMPA TOLD ME THE ASSIGNED ALT WAS 2100 FT, NOT 1200 FT. I ASKED TAMPA WHAT THEY WANTED ME TO DO, BUT THEIR ANSWER WAS UNCLR. THEY WERE QUITE BUSY. I STARTED A CLB TO 2100 FT, AT 1800 FT TAMPA TOLD ME TO CLB TO 2100 FT IMMEDIATELY AND I COMPLIED. THE REMAINDER OF THE FLT WAS NORMAL AND I MADE AN UNEVENTFUL LNDG AT SARASOTA. PERHAPS I HEARD WRONG, PERHAPS TAMPA MADE A MISTAKE, ONLY THE TAPE CAN TELL. HUMAN ERROR PERSISTS HOWEVER I WOULD HAVE KNOWN WHAT THE CTLR HAD WANTED ME TO DO, CLB TO 2100 FT, IF HE HAD SAID SO INSTEAD OF JUST INFORMING ME THAT THE ASSIGNED ALT WAS 2100 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.