Narrative:

I had flown to nashville in the morning. I spent a good part of the day outdoors in the sun and did not drink much water. As I taxied out, I was aware I was hot. I called for my clearance and initially ATC could not find it. Eventually, I was cleared as filed, initial climb to 3000 ft. I set the autoplt for 3000 ft to remind myself of the altitude. On being released, I was told to fly runway heading -- I think -- but it did not sink in. After takeoff, instead of holding runway heading, I turned on course and had climbed to 3600 ft before ATC called and I realized my error. I then had some difficulty understanding the heading ATC wanted. Shortly after that, I was cleared to climb higher where it was cooler. I also opened and drank a soft drink. I rapidly felt better and more on top of things. The remainder of the flight went without incident, so I concluded I was dehydrated. I have read of performance loss when dehydrated and now have a better understanding of it.

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Original NASA ASRS Text

Title: AN SMA PLT, DEPARTING BNA, IN ADDITION TO TURNING ON COURSE, CONTRARY TO HIS ATC CLRNC, OVERSHOT HIS ASSIGNED ALT.

Narrative: I HAD FLOWN TO NASHVILLE IN THE MORNING. I SPENT A GOOD PART OF THE DAY OUTDOORS IN THE SUN AND DID NOT DRINK MUCH WATER. AS I TAXIED OUT, I WAS AWARE I WAS HOT. I CALLED FOR MY CLRNC AND INITIALLY ATC COULD NOT FIND IT. EVENTUALLY, I WAS CLRED AS FILED, INITIAL CLB TO 3000 FT. I SET THE AUTOPLT FOR 3000 FT TO REMIND MYSELF OF THE ALT. ON BEING RELEASED, I WAS TOLD TO FLY RWY HDG -- I THINK -- BUT IT DID NOT SINK IN. AFTER TKOF, INSTEAD OF HOLDING RWY HDG, I TURNED ON COURSE AND HAD CLBED TO 3600 FT BEFORE ATC CALLED AND I REALIZED MY ERROR. I THEN HAD SOME DIFFICULTY UNDERSTANDING THE HDG ATC WANTED. SHORTLY AFTER THAT, I WAS CLRED TO CLB HIGHER WHERE IT WAS COOLER. I ALSO OPENED AND DRANK A SOFT DRINK. I RAPIDLY FELT BETTER AND MORE ON TOP OF THINGS. THE REMAINDER OF THE FLT WENT WITHOUT INCIDENT, SO I CONCLUDED I WAS DEHYDRATED. I HAVE READ OF PERFORMANCE LOSS WHEN DEHYDRATED AND NOW HAVE A BETTER UNDERSTANDING OF IT.

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.