PA28 pilot descended below cleared altitude. Inattn and poor radio technique contributed to the erro...

Attributes
ACN	594472
Time
Date	200309
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : mob.airport
State Reference	AL
Altitude	msl bound lower : 6000 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	PA-28 Cherokee Arrow IV
Operating Under FAR Part	Part 91
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 25 flight time total : 3200 flight time type : 2600
ASRS Report	594472
Person 2
Affiliation	government : faa
Function	controller : approach
Events
Anomaly	altitude deviation : overshoot non adherence : clearance non adherence : far
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance Environmental Factor Airspace Structure
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

ZHU cleared me from 13000-11000 ft and had me call mob approach. I thought, that approach cleared me on down to 6000 ft. Later, a different approach controller said I had only been cleared to 9000 ft. I was busy and apparently heard 6000 ft and wrote that down. If I reported back 6000 ft, no correction was called. If I wrote 6000 ft and called back 9000 ft, that would certainly be my error. I believe I was very busy and perhaps heard 9000 ft, but didn't write it down immediately. What I should have done is check with approach about the altitude before writing down anything. I believe contributing factors may be that I had been cruising for 3+ hours at 13000 ft (with oxygen) and becoming very busy after 3+ hours of very routine cavu cruising.

Original NASA ASRS Text

Title: PA28 PLT DSNDED BELOW CLRED ALT. INATTN AND POOR RADIO TECHNIQUE CONTRIBUTED TO THE ERROR.

Narrative: ZHU CLRED ME FROM 13000-11000 FT AND HAD ME CALL MOB APCH. I THOUGHT, THAT APCH CLRED ME ON DOWN TO 6000 FT. LATER, A DIFFERENT APCH CTLR SAID I HAD ONLY BEEN CLRED TO 9000 FT. I WAS BUSY AND APPARENTLY HEARD 6000 FT AND WROTE THAT DOWN. IF I RPTED BACK 6000 FT, NO CORRECTION WAS CALLED. IF I WROTE 6000 FT AND CALLED BACK 9000 FT, THAT WOULD CERTAINLY BE MY ERROR. I BELIEVE I WAS VERY BUSY AND PERHAPS HEARD 9000 FT, BUT DIDN'T WRITE IT DOWN IMMEDIATELY. WHAT I SHOULD HAVE DONE IS CHK WITH APCH ABOUT THE ALT BEFORE WRITING DOWN ANYTHING. I BELIEVE CONTRIBUTING FACTORS MAY BE THAT I HAD BEEN CRUISING FOR 3+ HRS AT 13000 FT (WITH OXYGEN) AND BECOMING VERY BUSY AFTER 3+ HRS OF VERY ROUTINE CAVU CRUISING.

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.

PA28 pilot descended below cleared altitude. Inattn and poor radio technique contributed to the error.