BECAUSE OF PAX ILLNESS; ACR FLC MAKES PRECAUTIONARY LNDG AT MSP. FIRST ATTEMPT TO LAND RESULTS IN MISSED APCH ACCOUNT NAVAID MALFUNCTION.

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APPROX 100 MI W OF MSP AT 41000 FT WE HAD THE FIRST WARNING OF POSSIBLE MEDICAL PROB. THE FO STARTED PREPARING IN THE EVENT WE HAD TO DIVERT. CHKING WX AND GETTING OUT APCH PLATES; ADVISING SYS OPS CTL. OVERHEAD MSP THE FLT ATTENDANT ADVISED WE NEEDED TO LAND. I GAVE CTL OF THE ACFT TO THE FO AND TOOK CARE OF ATIS APCH. SET UP COMPANY COM; APCH BRIEFING; ETC. MSP APCH CTL BROUGHT US RIGHT IN. THE WX HAD BEEN GOOD BUT RAIN WAS IN AREA. WE WERE ON APCH AT 4000 FT; WERE CLRED TO INTERCEPT THE LOC; CLRED FOR APCH. WE INTERCEPTED THE LOC AND TRACKING ON AUTOPLT; APU ARMED. SHORTLY THEREAFTER THE ACFT TURNED R; AUTOPLT TRIPPED AND ALARM; ILS FLAG. WE WERE NOW R OF COURSE FOR RWY 12L AND ASKED FOR LNDG CLRNC ON RWY 12R WHICH WE COULD SEE THROUGH THE RAIN -- TWR CLRED US. HOWEVER WE WERE NOW HIGH AND HOT FOR A SHORT WET RWY AND EXECUTED A MISSED APCH. ATC BROUGHT US RIGHT AROUND FOR APCH AND LNDG ON RWY 12L. AFTER LNDG ON THE SECOND ATTEMPT WE NOTICED A LONG LINE OF ACFT AWAITING TKOF FROM RWY 12L. I SUSPECT THE LOC INTERFERENCE MAY HAVE COME FROM A CELLPHONE OR OTHER ELECTRICAL DEVICE ABOARD ONE OF THESE ACFT IN LINE FOR DEP. AN ACFT 3 OR 4 MI BEHIND US RPTED PROBS WITH THE LOC AS WELL. THE TWR HOWEVER RPTED THAT IT WAS MONITORING NORMAL. SUPPLEMENTAL INFO FROM ACN 436290: DIVERTED ENRTE TO MSP FOR MEDICAL EMER. DURING VECTORS FOR ILS RWY 12L APCH CAPT VERIFIED ILS IDENTIFIER AND AUTOPLTS CAPTURED THE APCH COURSE. JUST OUTSIDE OF THE OM COMMAND BARS BEGAN STEERING FOR COURSE CORRECTION TO THE R. SHORTLY THEREAFTER AUTOPLT DISCONNECTED; COMMAND BARS DISAPPEARED AND LOSS OF LOC SIGNAL WAS DISPLAYED. APCH QUERIED US AS WE WERE DRIFTING R OF COURSE AND WE BEGAN CORRECTING BACK TO THE L. WX AT THE TIME WAS APPROX 2 MI VISIBILITY WITH MODERATE RAIN SHOWERS. AT ABOUT THE SAME TIME; A FLT BEHIND US COMMENTED ON LOSS/INTERMITTENT LOC SIGNAL. AT THIS TIME APCH CTLR OFFERED A VISUAL APCH TO RWY 12R AND AS IT CAME INTO VIEW WE WERE OUT OF POS TO LAND. GAR WAS ACCOMPLISHED AND VECTORS FOR ILS RWY 12R AND LNDG WAS COMPLETED UNEVENTFULLY. ATC DID NOT INDICATE ANY CONFLICTS WITH TFC DURING FIRST APCH OR GAR. MSP APCH AND TWR WERE VERY HELPFUL AND PROFESSIONAL THROUGHOUT DIVERT AND LNDG.