AFTER THE PLT ARRIVED AT THE ARPT, A PERSON (WHO LATER WITNESSED THE ACCIDENT) DROVE THE PLT DOWN THE STRIP TO EXAMINE THE RWY. THE WITNESS ASKED THE PLT NOT TO TAKE OFF BECAUSE THE STRIP WAS TOO WET. THE PLT, WHO WAS A SURGEON, TOLD THE WITNESS THAT HE HAD 3 OPERATIONS THE FOLLOWING MORNING & HAD TO RETURN. ACCORDING TO THE WITNESS, THE PLT WENT FROM NORTH TO SOUTH ON THE RWY TO CHECK THE WATER, THEN HE MADE A 2ND RUN TOWARD THE NORTH TO TAKEOFF. HE SAID THAT THE ACFT LEFT THE GROUND & WAS APRX 20 FT AGL WHEN IT HEADED OFF THE NORTHWEST CORNER OF THE RWY TOWARD TALL PINES. HE STATED THE 'PLT PULL BACK & STALLED OUT & FELL FLAT' AT THE NORTH END OF THE RWY. ALSO, HE REPORTED THAT THE WIND SWITCHED TO THE SOUTH-SOUTHWEST AS THE ACFT TOOK OFF. THE ACFT IMPACTED NEAR THE END OF THE RWY & SUBSEQUENTLY HIT A DITCH. REPORTEDLY, THERE WAS STANDING WATER & GRASS, 6 TO 10 INCHES TALL, ON THE RWY. WITNESSES REPORTED LARGE 'ROOSTER TAILS' OF WATER BEHIND THE ACFT AS IT WAS ON THE TAKEOFF ROLL.