SINGLE PLT OF SMT OVERSHOOTS ASSIGNED ALT IN CLB.

Narrative

DURING CLBOUT TO 11000 FT; I BECAME DISTRACTED BY ONE OF MY PAX AROUND 10500 FT. I HAD THE FLT DIRECTOR COUPLED TO THE AUTOPLT AND THE AUTO LEVEL FUNCTION SET FOR 11000 FT. I NOTICED AT 11300 FT THAT THE ACFT DID NOT LEVEL. I DISCONNECTED THE AUTOPLT AND STARTED A PUSHOVER. BY THE TIME THIS WAS ACCOMPLISHED THE PLANE WENT THROUGH 11400 FT BEFORE STARTING DOWN. ATC THEN TOLD ME TO CLB TO 14000 FT; SO I REVERSED AND CONTINUED THE CLB. ATC CLAIMS I WENT THROUGH 11800 FT. I DID NOT. ACCORDING TO THE ALTIMETER IN MY ACFT; THE HIGHEST THAT I WENT WAS BTWN 11400 FT AND 11500 FT. I STARTED DOWN; THEN CTR SAID TO CLB TO 14000 FT AND MAINTAIN VISUAL SEPARATION. I SHOULD NOT HAVE LET THE PAX DISTRACT ME SO CLOSE TO LEVELOFF; NOR SHOULD I HAVE RELIED ON THE AUTOPLT SYS SO MUCH EVEN THOUGH IT IS AUTH IN LIEU OF A SIC. AS I RECALL; THERE WAS SOME HESITATION ON CTR'S PART AS TO WHAT THEY WANTED ME TO DO ONCE IT WAS IDENTED THAT I WAS HIGH. I STARTED DOWN; THEN HE CALLED MY CALL SIGN; HESITATED AND THEN TOLD ME TO CLB. I MADE THE MISTAKE OF MISSING MY LEVELOFF ALT; BUT IT WAS NOT BY 800 FT; 450-500 FT AT THE MOST.