Narrative:

I had been flying at 15000 ft MSL almost all day. As I neared the end of my second 3 1/2 hour leg; someone on the ZHU frequency mentioned that they had needed to get in touch with an aircraft and that they had used 121.5 to do so. Hearing this reminded me that I should monitor 121.5 when able. I promptly tuned #2 to 121.5 and put it on speaker. Center frequency was quiet for 5 mins or so; and I checked my chart to see whose sector I was in. Then I realized I'd missed a handoff because I'd changed the wrong radio. Contacted jax immediately and was greeted normally; so I suppose I wasn't off houston for long. The incident scared me a little and made me think of hypoxia. I'd had a headache and felt fatigued for much of the flight. I checked my oxygen supply -- all looked normal. Still; I turned up the flow. Upon getting more oxygen; my head soon felt better. In fact; I felt much better overall. I'll watch for these symptoms more closely in the future.

Google
 

Original NASA ASRS Text

Title: C210 PLT ATTRIBUTES RADIO TUNING ERROR TO HYPOXIA.

Narrative: I HAD BEEN FLYING AT 15000 FT MSL ALMOST ALL DAY. AS I NEARED THE END OF MY SECOND 3 1/2 HR LEG; SOMEONE ON THE ZHU FREQ MENTIONED THAT THEY HAD NEEDED TO GET IN TOUCH WITH AN ACFT AND THAT THEY HAD USED 121.5 TO DO SO. HEARING THIS REMINDED ME THAT I SHOULD MONITOR 121.5 WHEN ABLE. I PROMPTLY TUNED #2 TO 121.5 AND PUT IT ON SPEAKER. CTR FREQ WAS QUIET FOR 5 MINS OR SO; AND I CHKED MY CHART TO SEE WHOSE SECTOR I WAS IN. THEN I REALIZED I'D MISSED A HDOF BECAUSE I'D CHANGED THE WRONG RADIO. CONTACTED JAX IMMEDIATELY AND WAS GREETED NORMALLY; SO I SUPPOSE I WASN'T OFF HOUSTON FOR LONG. THE INCIDENT SCARED ME A LITTLE AND MADE ME THINK OF HYPOXIA. I'D HAD A HEADACHE AND FELT FATIGUED FOR MUCH OF THE FLT. I CHKED MY OXYGEN SUPPLY -- ALL LOOKED NORMAL. STILL; I TURNED UP THE FLOW. UPON GETTING MORE OXYGEN; MY HEAD SOON FELT BETTER. IN FACT; I FELT MUCH BETTER OVERALL. I'LL WATCH FOR THESE SYMPTOMS MORE CLOSELY IN THE FUTURE.

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.