Narrative:

In retrospect; it is clear to me that I encountered an advanced case of hypoxia in my VFR descent. I had been cruising for about 4 hours with flight following at 12500 ft; and the flight at that altitude had been progressing uneventfully. When I announced to center that I would commence a VFR descent; I was handed off to another sector. This is when things went awry. I think I may have heard wrong or selected a wrong frequency; but my attempts at contact went nowhere; and somehow I was unable to return to my previous controller. This seems incredible for a pilot with my level of experience; but; while flying the airplane was no problem; handling even the most simple mental tasks became almost impossible. As a result; I entered class B airspace without a clearance. I am 73 yrs old; but am in excellent health; have never smoked; and do not drink alcohol. But I realize now that; obviously; prolonged flight; even at the legal altitude of 12500 ft; can have a very detrimental effect on one's mental capacity. Also in retrospect; I remember that it was rather warm at altitude. This would have raised the density altitude even further. I received a real education; and one of the first things I will invest in will be portable oxygen equipment.

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Original NASA ASRS Text

Title: BE35 PLT ATTRIBUTES AIRSPACE VIOLATION AND IMPAIRED MENTAL ABILITY TO HYPOXIA RESULTING FROM FLT AT 12500 FT.

Narrative: IN RETROSPECT; IT IS CLR TO ME THAT I ENCOUNTERED AN ADVANCED CASE OF HYPOXIA IN MY VFR DSCNT. I HAD BEEN CRUISING FOR ABOUT 4 HRS WITH FLT FOLLOWING AT 12500 FT; AND THE FLT AT THAT ALT HAD BEEN PROGRESSING UNEVENTFULLY. WHEN I ANNOUNCED TO CTR THAT I WOULD COMMENCE A VFR DSCNT; I WAS HANDED OFF TO ANOTHER SECTOR. THIS IS WHEN THINGS WENT AWRY. I THINK I MAY HAVE HEARD WRONG OR SELECTED A WRONG FREQ; BUT MY ATTEMPTS AT CONTACT WENT NOWHERE; AND SOMEHOW I WAS UNABLE TO RETURN TO MY PREVIOUS CTLR. THIS SEEMS INCREDIBLE FOR A PLT WITH MY LEVEL OF EXPERIENCE; BUT; WHILE FLYING THE AIRPLANE WAS NO PROB; HANDLING EVEN THE MOST SIMPLE MENTAL TASKS BECAME ALMOST IMPOSSIBLE. AS A RESULT; I ENTERED CLASS B AIRSPACE WITHOUT A CLRNC. I AM 73 YRS OLD; BUT AM IN EXCELLENT HEALTH; HAVE NEVER SMOKED; AND DO NOT DRINK ALCOHOL. BUT I REALIZE NOW THAT; OBVIOUSLY; PROLONGED FLT; EVEN AT THE LEGAL ALT OF 12500 FT; CAN HAVE A VERY DETRIMENTAL EFFECT ON ONE'S MENTAL CAPACITY. ALSO IN RETROSPECT; I REMEMBER THAT IT WAS RATHER WARM AT ALT. THIS WOULD HAVE RAISED THE DENSITY ALT EVEN FURTHER. I RECEIVED A REAL EDUCATION; AND ONE OF THE FIRST THINGS I WILL INVEST IN WILL BE PORTABLE OXYGEN EQUIP.

Data retrieved from NASA's ASRS site as of January 2009 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.