M20P pilot started descent to traffic pattern altitude without ATC approval.

Attributes
ACN	500409
Time
Date	200102
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : cdw.airport
State Reference	NJ
Altitude	msl bound lower : 2600 msl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : n90.tracon
Operator	general aviation : personal
Make Model Name	M-20 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Route In Use	approach : traffic pattern approach : visual
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : multi engine pilot : instrument pilot : cfi
Experience	flight time last 90 days : 45 flight time total : 640 flight time type : 75
ASRS Report	500409
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : published procedure other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : anomaly accepted
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 was at 3000 ft, 2 NM east of mmu, and was told to enter a downwind for runway 22 at cdw (my destination). I believed that since new york TRACON told me to 'enter the right downwind for runway 22' I was cleared to descend to pattern altitude, as the 'downwind' only exists in the pattern, not 3000 ft. As I was descending through 2600 ft, approach controller got upset and insisted he did not clear me for the visual approach. While I agree the standard phraseology is 'cleared for the visual approach runway 22,' an instruction to enter part of the traffic pattern to an airport implied you have to descend to pattern altitude. I feel to avoid confusion, the controller should have stated 'enter the downwind for runway 22, maintain 3000 ft.' by issuing the nonstandard 'enter the downwind,' I mistakenly thought he wanted me to descend, as I was 3 NM from the runway when he issued the instruction.

Original NASA ASRS Text

Title: M20P PLT STARTED DSCNT TO TFC PATTERN ALT WITHOUT ATC APPROVAL.

Narrative: I WAS AT 3000 FT, 2 NM E OF MMU, AND WAS TOLD TO ENTER A DOWNWIND FOR RWY 22 AT CDW (MY DEST). I BELIEVED THAT SINCE NEW YORK TRACON TOLD ME TO 'ENTER THE R DOWNWIND FOR RWY 22' I WAS CLRED TO DSND TO PATTERN ALT, AS THE 'DOWNWIND' ONLY EXISTS IN THE PATTERN, NOT 3000 FT. AS I WAS DSNDING THROUGH 2600 FT, APCH CTLR GOT UPSET AND INSISTED HE DID NOT CLR ME FOR THE VISUAL APCH. WHILE I AGREE THE STANDARD PHRASEOLOGY IS 'CLRED FOR THE VISUAL APCH RWY 22,' AN INSTRUCTION TO ENTER PART OF THE TFC PATTERN TO AN ARPT IMPLIED YOU HAVE TO DSND TO PATTERN ALT. I FEEL TO AVOID CONFUSION, THE CTLR SHOULD HAVE STATED 'ENTER THE DOWNWIND FOR RWY 22, MAINTAIN 3000 FT.' BY ISSUING THE NONSTANDARD 'ENTER THE DOWNWIND,' I MISTAKENLY THOUGHT HE WANTED ME TO DSND, AS I WAS 3 NM FROM THE RWY WHEN HE ISSUED THE INSTRUCTION.

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.