Bonanza 35
Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 40; Flight Crew Total 2100; Flight Crew Type 1600
Physiological - Other
Aircraft Equipment Problem Critical; Airspace Violation All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance
Human Factors
I was flying VFR using oxygen through a cannula and GPS navigation and became confused and unable to restore my GPS receiver to the flight track page. During this time; the aircraft apparently climbed to 18;400 feet although I did not realize it at the time. I was using radar flight following and the controller asked me to descend. Once at an altitude under 10;000 feet; he told me that he as well as other pilots listening on the frequency believed that I had become hypoxic. I acknowledged that it was possible; but was regularly checking my oxygen flow which indicated sufficient for 18;000 feet.I received a call today from FAA notifying me that I had a Class Alfa incursion which surprised me because I have no recollection whatsoever of being told that by the radar controller. That pretty much convinces me that I was indeed hypoxic without realizing it; since the FAA representatives heard me notified on the taped conversation. At this point I don't really understand how it could have happened with the flow meter indicating as much as it did. I will inspect the cannula to see if there might be a leak somewhere downstream of the flow meter. I routinely inspect the cannula and hoses; but realize that I must inspect them much more carefully in the future. I always carry a spare cannula for just such a situation; but it never occurred to me that I needed it when I actually needed it; if it turns out to be the problem.
BE35 pilot reported he experienced a Class A airspace incursion possibly because of the effects of hypoxia.