A CPR CAPT EXPERIENCED A GPS FAILURE AND IS CONCERNED THAT HE MAY HAVE MADE AN ERRONEOUS POS RPT.

Narrative

I WAS RETURNING TO SALT LAKE CITY FROM BIG PINEY; WY. WE WERE PROCEEDING DIRECT TO LHO VOR FOR THE BRIGHAM CITY ARR INTO SLC WHEN APPROX 20 MI NE OF CARTR INTXN; MY GPS BEGAN SHOWING SIGNS OF FAILING. IT BEGAN INDICATING MULTIPLE HDGS TO CARTR. ALMOST IMMEDIATELY; MY XPONDER QUIT WORKING. BY THIS TIME; WE ARE OVER CARTR INTXN. JUST PRIOR (ABOUT 2 MINS) THE CTR CTLR ASKED FOR A POS RPT. I TOLD HIM WE WERE 15 MI N OF CARTR. THE NEXT CTLR (APCH) ASKED MY POS AND ALT OVER CARTR OR JUST PAST CARTR. I WAS TRYING TO MAKE THE ALT READOUT WORK FOR THEM AND TOLD HIM I WAS AT 14500 FT WHEN I WAS ACTUALLY AT 15000 FT ASSIGNED. THE STANDBY POS WAS SELECTED ON THE ALTIMETER. MY POS THAT I GAVE HIM WAS ESTIMATED. AFTER ALL THIS; THE CTLR ASKED ME IF I COULD MAKE MY LNDG AT SALT LAKE FROM A STRAIGHT-IN APCH. I TOLD HIM YES; BUT WAS THEN INSTRUCTED TO MAKE A L 360 DEG TURN; WHICH I DID. APCH AND LNDG WERE UNEVENTFUL FROM THAT POINT. BEING SO CLOSE IN TO THE ARPT; WITH MULTIPLE FAILURES OCCURRING WITH MY EQUIP; MAY HAVE CONTRIBUTED TO A POS RPT THAT WAS LESS THAN ACCURATE.