C172 pilot enters downwind instead of base leg as instructed by hgr tower.

Attributes
ACN	596943
Time
Date	200310
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : hgr.airport
State Reference	MD
Altitude	msl single value : 1700
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : hgr.tower
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Route In Use	approach : traffic pattern
Flight Plan	None
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 31 flight time total : 959 flight time type : 656
ASRS Report	596943
Person 2
Affiliation	other
Function	controller : local
Events
Anomaly	non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I contacted hagerstown, md, tower outside of class D airspace, told tower I was landing at hgr. Tower said they told me to 'enter a left base for runway 27.' when I got near the runway, I entered a 45 degree left downwind for runway 27. Tower asked why I did that. I thought tower said to 'report left base runway 27.' initially I was surprised at the confusion and told the tower I didn't know why I did that. Later, I explained how I understood their instructions. Prior to setting up for the landing, I should have asked the tower to clarify their instruction since a fair amount of time had passed between the time they issued the instructions and the time I was ready to enter the traffic pattern.

Original NASA ASRS Text

Title: C172 PLT ENTERS DOWNWIND INSTEAD OF BASE LEG AS INSTRUCTED BY HGR TWR.

Narrative: I CONTACTED HAGERSTOWN, MD, TWR OUTSIDE OF CLASS D AIRSPACE, TOLD TWR I WAS LNDG AT HGR. TWR SAID THEY TOLD ME TO 'ENTER A L BASE FOR RWY 27.' WHEN I GOT NEAR THE RWY, I ENTERED A 45 DEG L DOWNWIND FOR RWY 27. TWR ASKED WHY I DID THAT. I THOUGHT TWR SAID TO 'RPT L BASE RWY 27.' INITIALLY I WAS SURPRISED AT THE CONFUSION AND TOLD THE TWR I DIDN'T KNOW WHY I DID THAT. LATER, I EXPLAINED HOW I UNDERSTOOD THEIR INSTRUCTIONS. PRIOR TO SETTING UP FOR THE LNDG, I SHOULD HAVE ASKED THE TWR TO CLARIFY THEIR INSTRUCTION SINCE A FAIR AMOUNT OF TIME HAD PASSED BTWN THE TIME THEY ISSUED THE INSTRUCTIONS AND THE TIME I WAS READY TO ENTER THE TFC PATTERN.

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.