PLT OF C172 USING GPS NAV ENTERS CLASS B AIRSPACE WITHOUT CLRNC. USE OF VISUAL CUES CONFLICTS WITH GPS INFO WHICH RPTR DOES NOT BELIEVE.

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I PLANNED THE FLT USING CIRRUS INTERFACE FOR DUATS ON MY HOME COMPUTER. I DID NOT FILE A FLT PLAN BECAUSE I COULD NOT FIND A WAY TO EASILY DESCRIBE MY RTE ON THE FORM. PLAN: USING A FLYING CLUB C172; I WOULD DEPART VFR FROM MIC (WHICH IS 12 MI NE OF MSP) AT 180 DEGS; FLY AT 2100 FT UNDER THE MSP CLASS B 2300 FT FLOOR; AND FOLLOW THE RING COUNTERCLOCKWISE; EVENTUALLY DEPARTING THE CLASS B AT 40 DEGS; DIRECT TO VOYAGER VILLAGE; A PVT STRIP 60 NM AWAY. ALTHOUGH I HEADED OUT OVER GND I'D NEVER BEFORE COVERED; I LEFT WITH THE UNJUSTIFIED CONFIDENCE OF FLYING A VERY FAMILIAR AIRPLANE FROM A VERY FAMILIAR FIELD. FOR THE FIRST LEG I WAS TO HEAD 180 DEGS STAYING W OF HWY 100; A N-S EXPRESSWAY THAT WOULD TAKE ME TO THE INNER EDGE OF THE MSP CLASS B 2300 FT RING. I MISIDENTED THE ROAD AND VERIFIED ITS N-S ORIENTATION FROM MY (PRECESSED) DIRECTIONAL GYRO; THEN FOLLOWED IT ON A HDG ABOUT 130 DEGS; WHICH WAS READING 180 DEGS ON MY DIRECTIONAL GYRO. WITHIN 5 MINS I UNKNOWINGLY FLEW INTO THE MSP CLASS B INNER CIRCLE. I PASSED CLOSER TO THE SKYSCRAPERS OF THE CITY THAN I EXPECTED BUT I JUSTIFIED IT WITH KNOWING I'D NEVER BEEN IN THIS INNER RING BEFORE. AFTER ALL; I WAS STILL W OF I-494. I SUPPRESSED A VAGUE SENSE OF 'THIS DOESN'T QUITE ADD UP.' I TRIED TO GET THE NEW GPS UNIT TO CONFIRM MY POS; BUT COULDN'T GET THE OUTPUT TO MAKE SENSE. I FELT I WAS PAYING ADEQUATE ATTN TO THE AIRPLANE AND THE SIT; BUT MY WIFE TELLS ME I SPENT MOST OF MY TIME 'HEAD DOWN' ON THE GPS. MY FIRST CHKPOINT WAS AT ABOUT 10 MINS; FCM; CLASS D. I SAW AN ARPT AHEAD AND TO THE R; DID NOT REALIZE IT WAS MSP. WHEN GPS TOLD ME I WAS 8 MI OUT; I CALLED FCM TWR TO TRAVERSE THE CLASS D AIRSPACE. THE TWR TOLD ME TO CLB TO 2500 FT AND CALL BACK WHEN I WAS LEAVING THE CLASS D. I ASSUMED I HAD BEEN SPOTTED OR SEEN ON THE RADAR. EVEN THOUGH FCM CTLR NEVER CONFIRMED MY POS; THE ACKNOWLEDGEMENT AND INSTRUCTION SERVED TO CONFIRM MY MISTAKEN POS. AS I PASSED THROUGH THE APCH PATTERN OF THE ACTIVE RWYS ABOUT 2 NM N OF MSP; ITHOUGHT THE ARPT LOOKED BIGGER THAN I'D REMEMBERED; BUT REMINDED MYSELF THAT I'D NEVER BEFORE SEEN FCM FROM THIS DIRECTION AND LOW ALT. I DIDN'T EXAMINE IT MORE CLOSELY; BECAUSE I WAS ALREADY SPLITTING MY TIME BTWN SCANNING FOR ARPT TFC AND WORKING ON THE GPS UNIT. I CALLED FCM WHEN THE ARPT WAS ABOUT 5 NM BEHIND ME AND TOLD THE TWR I WAS EXITING THE AIRSPACE. THE TWR APPROVED A FREQ CHANGE AND I DROPPED TO 2100 FT TO STAY BELOW THE 2300 CLASS B FLOOR. THE CLASS D RADIO CONTACT ONCE AGAIN REASSURED ME THAT I WAS WHERE I WAS SUPPOSED TO BE. SINCE I COULDN'T GET THE GPS TO COOPERATE; I ABANDONED TRYING TO USE IT. I CHANGED MY FLT PLAN. INSTEAD OF USING THE GPS TO KEEP ME IN THE 6 NM TO 8.5 NM 2100 FT CLASS B RING; I CONTINUED 180 DEGS FLYING TOWARD A BODY OF WATER IN THE S WHICH I MISIDENTED AS PRIOR LAKE; ONCE AGAIN CONFIRMING MY INCORRECT POS. THEN 5 THINGS HAPPENED WITHIN 1 VERY LONG MIN. I SIGHTED A REFINERY ABOUT 5 NM AHEAD WHICH SUGGESTED I WAS WAY OFF COURSE. I SAW THAT THE DIRECTIONAL GYRO WAS READING ABOUT 45 DEGS DIFFERENT THAN THE COMPASS. I CONFIRMED MY POS AS I REALIZED THE BODY OF WATER WHICH I WAS FLYING TOWARD WAS PINE BEND IN THE MISSISSIPPI NOT PRIOR LAKE. I LOOKED BACK AT THE ARPT I THOUGHT WAS FCM AND SAW A BIG JET TOUCH DOWN. 'COULD THIS REALLY BE MSP?' I ASKED MYSELF. AND THE GPS READINGS SUDDENLY STARTED TO MAKE SENSE. I TRIED TO CALM MYSELF AS I ASSESSED THE SIT. AS I REALIZED I WAS LIKELY STILL IN THE CLASS B AIRSPACE I QUICKLY SCANNED FOR TFC; ESPECIALLY JET TFC; FINDING NONE. I CONSULTED THE MSP TERMINAL AREA CHART; CONFIRMING MY POS NOW OUTSIDE THE CLASS B. I STILL HADN'T PUT TOGETHER ALL THAT HAD HAPPENED. THE PSYCHOLOGICAL FORCE OF DENIAL WAS GREAT. I COULD NOT HAVE BUZZED MSP BECAUSE THAT WOULD MAKE ME AN INCOMPETENT AND CARELESS PLT; THERE HAD TO BE ANOTHER EXPLANATION. I DIDN'T KNOW WHAT TO DO. I RECALLED A LONG LECTURE BY AN EXPERIENCED PLT ABOUT AVOIDING SELF INCRIMINATION. SHOULD I CALL MSP TWR NOW? I NEEDED TO GET SOME ADVICE. ANDSOON. I HEADED FOR VOYAGER VILLAGE USING THE GPS AND THE VOR. WITHIN A FEW MINS I PASSED NEAR LAKE ELMO ARPT; 21D; AND MONITORED THE FREQ. ZMP CALLED ME BY MY TAIL NUMBER AND POLITELY REQUESTED I CALL THE TWR WHEN I LANDED. WHEN I GOT BACK TO MIC THE CLUB SAFETY OFFICER WAS WAITING FOR ME. WE CONFERRED. I CALLED THE MSP TWR. I STILL HAVE MY PPC AND HAVE ARRANGED FOR SOME INSTRUCTION. IF I GET THROUGH THIS PERSONAL CONFIDENCE CRISIS I'LL START WORKING TOWARD MY INST RATING. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES HIS CONVERSATION WITH CTR WAS FRIENDLY AND RESULTED IN A TOUR OF THE FACILITY WITH BETTER UNDERSTANDING OF THEIR CONCERNS AND PROCS. HE FEELS HE COULD HAVE AVOIDED THIS INCIDENT WITH BETTER USE OF CHKLIST WHICH WOULD HAVE CAUGHT THE PRECESSION ERROR IN THE COMPASS. THE PROB WAS THAT THE VISUAL EXPECTATIONS SEEMED RIGHT SO HE SPENT TOO MUCH TIME SCREWING AROUND WITH THE GPS. RPTR FEELS THE MANUFACTURER WOULD DO WELL TO PRESENT THE TRAINING INFO IN THE FORM OF MOST LIKELY SCENARIOS: TAKE THE USER THROUGH PROCS FROM ONE ARPT TO ANOTHER; THEN FROM ONE ARPT TO ANOTHER FURTHER AWAY WITH NEED FOR WAYPOINT ENTRY; THEN HOW TO CHANGE A WAYPOINT ENRTE. A PLAY BY PLAY WALK THROUGH OF THESE PROCS WOULD BE A BETTER TRAINING TECHNIQUE.