C172 PLT PROGRAMMING GPS UNIT STRAYS INTO CLASS C AIRSPACE WITHOUT CLRNC.

Narrative

TRAINING FLT IN NEW CESSNA 172R WITH GPS. AFTER DEPARTING MMU VFR TO MBJ; I WAS ATTEMPTING TO PROGRAM GPS. WHILST PROGRAMMING; I CLBED INTO CLASS B WITHOUT AUTH. WHEN GPS WAS PROGRAMMED; I NOTICED DME FROM LGA WAS ONLY 18.5 MI (CLASS B EXTENDS 20 MI; FLOOR OF CLASS B IS 3000 FT). I IMMEDIATELY DSNDED TO 2500 FT UNTIL BEYOND 20 MI OF LGA. I WAS IN CLASS B FOR ABOUT 5 MINS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT WHILE THE TRAINING MANUAL WAS 'EXCELLENT' IT WAS VERY COMPLEX. HE FEELS IT WOULD BE HELPFUL TO START WITH SIMPLE SCENARIOS AND WORK UP TO MORE DIFFICULT SCENARIOS SUCH AS AN INST APCH. IN THIS INCIDENT; HE WAS SPENDING A LOT OF TIME PROGRAMMING THE GPS AND NOT MONITORING THE ACFT ENOUGH. ANOTHER PROB IN THIS ACFT WAS THE CONNECTION OF THE DME IN SUCH A WAY THAT IT NEEDED TO BE SWITCHED FROM GPS TO VOR SEPARATELY AND HE DID NOT HAVE IT CONSISTENTLY SET ON LGA WHILE PROGRAMMING. HAVING USED A HAND-HELD GPS PREVIOUSLY; HE DID NOT HAVE THAT PROB. HIS CONSENSUS IS THAT IF YOU ARE GOING TO USE THE GPS AS A PRIMARY NAV INST; YOU HAD BETTER KNOW WHAT YOU ARE DOING BEFORE YOU GET IN THE AIR. IN FACT; HE SUGGESTS AT LEAST 3-5 HRS OF FLT INSTRUCTION IN THE USE OF GPS FOR IFR FLT.