BE35 pilot attributes heading and altdevs at 13000 ft to stress and hypoxia.

Attributes
ACN	608034
Time
Date	200312
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zoa.artcc
State Reference	CA
Altitude	msl single value : 13000
Environment
Flight Conditions	VMC
Weather Elements	Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa.artcc tower : zzz.tower
Operator	general aviation : personal
Make Model Name	Bonanza 35
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 1 flight time total : 660 flight time type : 10
ASRS Report	608034
Person 2
Affiliation	government : faa
Function	controller : radar
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather non adherence : far non adherence : clearance other spatial deviation
Resolutory Action	controller : issued new clearance controller : provided flight assist flight crew : exited adverse environment
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Environmental Factor Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I was rather anxious about a previous engine sputtering incident but decided it was better to fly now with good WX than to wait in hopes that my anxiety would subside. I accordingly planned a 1-DAY ski trip to a high altitude airport. On preflight, I noticed that my oxygen bottle was empty but I knew that my destination airport could be reached comfortably with only a 10 min visit to 13000 ft. I took off and 45 mins into my IFR flight plan was directed to climb and maintain 15000 ft. I told ATC that I needed a lower altitude because I did not have oxygen and was vectored to the 13000 ft airway and told to turn to 080 degrees. Believing that the VOR was to my left, I recall thinking, '080 degrees is 10 degrees left of north' and proceeded to steer 350 degrees. When center advised I was well off course, I could not understand how and continued to more carefully maintain my heading of 350 degrees. Center advised that my directional gyro must not be working properly and proceeded to give me relative heading changes to get me in sight of my destination airport and handed me off to the tower. When I landed, there was a message waiting for me to call the center supervisor who advised me how badly I had adhered to assigned headings and altitudes. Under normal circumstances, I know that I can function well at 12000 ft or even 13000 ft without oxygen. I discovered that, when anxious or stressed, the level at which I can function without oxygen is apparently a lot lower.

Original NASA ASRS Text

Title: BE35 PLT ATTRIBUTES HDG AND ALTDEVS AT 13000 FT TO STRESS AND HYPOXIA.

Narrative: I WAS RATHER ANXIOUS ABOUT A PREVIOUS ENG SPUTTERING INCIDENT BUT DECIDED IT WAS BETTER TO FLY NOW WITH GOOD WX THAN TO WAIT IN HOPES THAT MY ANXIETY WOULD SUBSIDE. I ACCORDINGLY PLANNED A 1-DAY SKI TRIP TO A HIGH ALT ARPT. ON PREFLT, I NOTICED THAT MY OXYGEN BOTTLE WAS EMPTY BUT I KNEW THAT MY DEST ARPT COULD BE REACHED COMFORTABLY WITH ONLY A 10 MIN VISIT TO 13000 FT. I TOOK OFF AND 45 MINS INTO MY IFR FLT PLAN WAS DIRECTED TO CLB AND MAINTAIN 15000 FT. I TOLD ATC THAT I NEEDED A LOWER ALT BECAUSE I DID NOT HAVE OXYGEN AND WAS VECTORED TO THE 13000 FT AIRWAY AND TOLD TO TURN TO 080 DEGS. BELIEVING THAT THE VOR WAS TO MY L, I RECALL THINKING, '080 DEGS IS 10 DEGS L OF N' AND PROCEEDED TO STEER 350 DEGS. WHEN CTR ADVISED I WAS WELL OFF COURSE, I COULD NOT UNDERSTAND HOW AND CONTINUED TO MORE CAREFULLY MAINTAIN MY HDG OF 350 DEGS. CTR ADVISED THAT MY DIRECTIONAL GYRO MUST NOT BE WORKING PROPERLY AND PROCEEDED TO GIVE ME RELATIVE HDG CHANGES TO GET ME IN SIGHT OF MY DEST ARPT AND HANDED ME OFF TO THE TWR. WHEN I LANDED, THERE WAS A MESSAGE WAITING FOR ME TO CALL THE CTR SUPVR WHO ADVISED ME HOW BADLY I HAD ADHERED TO ASSIGNED HDGS AND ALTS. UNDER NORMAL CIRCUMSTANCES, I KNOW THAT I CAN FUNCTION WELL AT 12000 FT OR EVEN 13000 FT WITHOUT OXYGEN. I DISCOVERED THAT, WHEN ANXIOUS OR STRESSED, THE LEVEL AT WHICH I CAN FUNCTION WITHOUT OXYGEN IS APPARENTLY A LOT LOWER.

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.