C310 pilot misreads altimeter by 10000 ft arriving las.

Attributes
ACN	446710
Time
Date	199908
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : bld.vortac
State Reference	NV
Altitude	msl bound lower : 11000 msl bound upper : 21000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : l30.tracon
Operator	general aviation : personal
Make Model Name	PA-46 Malibu
Operating Under FAR Part	Part 91
Navigation In Use	other vortac
Flight Phase	descent : intermediate altitude
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 84 flight time total : 4461 flight time type : 1935
ASRS Report	446710
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	non adherence : far non adherence : clearance non adherence : published procedure other anomaly other other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : provided flight assist controller : issued new clearance controller : issued alert none taken : detected after the fact
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Even though conditions were VFR for the entire route, I filed an IFR flight plan from reno to boulder city airport, J92 bty J86 bld direct at FL190. I was cleared to boulder city airport, reno 2 departure, V105 oal as filed. Originally cleared to FL190, I was later cleared to FL230. Subsequently, I was cleared to cross fuzzy intersection west of las vegas at 15000 ft. Later, las approach control cleared me down to 11000 ft. J86 is a straight line between the fuzzy intersection and the boulder city VOR. As I proceeded along this route at 11000 ft, the controller asked me for my heading. When I gave it to him, he asked me why I wasn't following the fuzzy arrival. I told him I was cleared J86 from fuzzy intersection to the boulder city VOR. He ordered a right turn and asked me to identify and for my altitude. I idented and told him I was at FL210. We quickly established that I was at 11000 ft. I do not know why I misread the altimeter. It could have been fatigue as I hadn't gotten much sleep the night before our XA55 departure. It could have been because I had been at the flight levels that day and the day before and that had been in my mind. Whatever the reason, it could have been exacerbated by my being flustered by the controller's accusatory tone about my not following an arrival procedure for which I had not received a clearance. In any event, I clearly made a mistake.

Original NASA ASRS Text

Title: C310 PLT MISREADS ALTIMETER BY 10000 FT ARRIVING LAS.

Narrative: EVEN THOUGH CONDITIONS WERE VFR FOR THE ENTIRE RTE, I FILED AN IFR FLT PLAN FROM RENO TO BOULDER CITY ARPT, J92 BTY J86 BLD DIRECT AT FL190. I WAS CLRED TO BOULDER CITY ARPT, RENO 2 DEP, V105 OAL AS FILED. ORIGINALLY CLRED TO FL190, I WAS LATER CLRED TO FL230. SUBSEQUENTLY, I WAS CLRED TO CROSS FUZZY INTXN W OF LAS VEGAS AT 15000 FT. LATER, LAS APCH CTL CLRED ME DOWN TO 11000 FT. J86 IS A STRAIGHT LINE BTWN THE FUZZY INTXN AND THE BOULDER CITY VOR. AS I PROCEEDED ALONG THIS RTE AT 11000 FT, THE CTLR ASKED ME FOR MY HDG. WHEN I GAVE IT TO HIM, HE ASKED ME WHY I WASN'T FOLLOWING THE FUZZY ARR. I TOLD HIM I WAS CLRED J86 FROM FUZZY INTXN TO THE BOULDER CITY VOR. HE ORDERED A R TURN AND ASKED ME TO IDENT AND FOR MY ALT. I IDENTED AND TOLD HIM I WAS AT FL210. WE QUICKLY ESTABLISHED THAT I WAS AT 11000 FT. I DO NOT KNOW WHY I MISREAD THE ALTIMETER. IT COULD HAVE BEEN FATIGUE AS I HADN'T GOTTEN MUCH SLEEP THE NIGHT BEFORE OUR XA55 DEP. IT COULD HAVE BEEN BECAUSE I HAD BEEN AT THE FLT LEVELS THAT DAY AND THE DAY BEFORE AND THAT HAD BEEN IN MY MIND. WHATEVER THE REASON, IT COULD HAVE BEEN EXACERBATED BY MY BEING FLUSTERED BY THE CTLR'S ACCUSATORY TONE ABOUT MY NOT FOLLOWING AN ARR PROC FOR WHICH I HAD NOT RECEIVED A CLRNC. IN ANY EVENT, I CLRLY MADE A MISTAKE.

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.