PLT OF A BEECH T34; MENTOR; DURING A NIGHT CURRENCY FLT; INADVERTENTLY CLBED INTO CLASS C AIRSPACE WHILE LOOKING FOR HIS DEST ARPT. THE ARPT (NON TWR) WAS LOCATED BENEATH THE CLASS C AIRSPACE.

Narrative

I WAS ENRTE FROM OFF TO CBF FOR NIGHT LNDG CURRENCY. DEPARTING OFF; I WAS IN CONTACT WITH OMA APCH ON 120.1. WHEN I ESTIMATED I WAS APPROX 5 MI SW OF CBF; APCH CLRED ME TO CHANGE RADIO FREQ AND TO SQUAWK 1200. I SWITCHED TO CBF; 122.8; AND STARTED A DSCNT OUT OF 3000 FT MSL. THE BASE OF THE CLASS C OUTER RING AIRSPACE IS 2500 FT MSL. I HAD LET DOWN BELOW 2500 FT MSL AND WAS LOOKING FOR THE CBF ARPT. THE PROB STARTED WHEN I INADVERTENTLY OVERFLEW THE CBF ARPT WITHOUT SEEING THE ARPT. I WAS NOW 3-4 MI NE OF CBF AND STARTED DOING TURNS TO LOCATE CBF. WHILE LOOKING FOR CBF; I DID NOT NOTICE MY ALT SLOWLY INCREASING. I RE-ENTERED THE OUTER RING OF THE CLASS C AIRSPACE FROM THE BOTTOM. THE CONTRIBUTING FACTOR WAS MY INATTN TO MY ALT INCREASE WHILE LOOKING FOR CBF. I DID NOT REALIZE I HAD VIOLATED THE CLASS C AIRSPACE UNTIL OMA CONTACTED ME ON THE CBF CTAF AND ADVISED ME OF WHAT I HAD DONE. IN HINDSIGHT; I SHOULD HAVE RECONTACTED OMA APCH TO REQUEST ASSISTANCE IN LOCATING CBF. AFTER I LANDED AT OFF; I TELEPHONED OMA APCH TO FURTHER CLARIFY ANY QUESTIONS WHICH THEY MAY HAVE HAD.