PA31 PLT DEPARTS MSN WITHOUT TKOF CLRNC.

Narrative

I TAXIED FROM THE RAMP AT MSN TO RWY 31. WHILE HOLDING SHORT OF RWY 31; I DID OBSERVE A SINGLE ENG CESSNA ON FINAL. THE CESSNA DID A TOUCH-AND-GO AND WHEN I CONTACTED TWR I WAS INSTRUCTED TO POS AND HOLD ON RWY 31. I TOOK RWY 31; STABILIZED THE ENGS AT TKOF PWR AND RELEASED THE BRAKES. ONCE AIRBORNE AND AT APPROX 300 FT AGL; TWR CONTACTED ME TO LET ME KNOW THAT I HAD DEPARTED WITHOUT A TKOF CLRNC. THE SINGLE ENG CESSNA THAT HAD DONE THE TOUCH-AND-GO WAS IN A R TURN AND PASSED OFF OF MY R WING AT APPROX 1/2 MI AND AT MY ALT. I FEEL THAT THERE WERE 3 CONTRIBUTING FACTORS INVOLVED WITH THIS OCCURRENCE. 1) AN ACFT (CITATION) BELONGING TO ANOTHER OPERATOR TAXIED ONTO THE RAMP AND I WAS THINKING ABOUT WHAT IT WOULD BE LIKE TO FLY FOR THEM. 2) NON STERILE COCKPIT DUE TO FRONT SEAT PAX AND OUR DISCUSSION OF THE OTHER OPERATOR. 3) MOST IMPORTANT; MY COMPLACENCY AND NOT PERFORMING THE TASK AT HAND. THIS SERVED AS A WAKE-UP CALL FOR ME. THE REALIZATION OF THE POSSIBLE CONSEQUENCES OF MY ACTIONS HIT ME A FEW MINS LATER. DURING THAT TKOF; I CROSSED 2 OTHER RWYS THAT HAD BEEN USED THAT DAY. QUINCY; IL; COMES TO MIND. 6 SOULS COULD HAVE BEEN KILLED THAT DAY ON MY ACFT. THAT'S ALL THE REASON I NEED TO DUTIFULLY PERFORM THE TASK AT HAND.