AN MD80 CREW SUSPECTS A LIGHTNING STRIKE CAUSED A RADIO ALT FAULT AND ILS GS ERRORS CAUSING THEM TO GAR FOR ANOTHER APCH WITH DIFFERENT RADIOS.

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ON ILS RWY 4 APCH INTO ZZZ THE CAPT'S RADIO ALTIMETER SHOWED A YELLOW 'RADIO ALTIMETER COMPARATOR' LIGHT FLASHING. THE FO HAD A RED RADIO ALTIMETER FLASHING LIGHT. I'M NOT SURE WHAT TYPE OF RED RADIO ALTIMETER LIGHT IT WAS. THE QRH INSTRUCTS THE PLT WITH WORKING INSTS TO FLY. I CONTINUED AS PF. WE HAD RECEIVED A GOOD ILS IDENT ON BOTH SIDES PRIOR TO THE APCH. AS WE WERE CLRED FOR THE APCH; THE LOC CAPTURED. WE WERE ABOVE THE GS DSNDING BUT THE GS SHOWED US HIGH BY FULL SCALE TO THE BOTTOM; INDICATING TO US; THE ACFT WAS HIGH. (IN RETROSPECT; I AM NOT SURE THAT WAS A CORRECT READING.) AT THAT POINT; TWR CLRED US TO LAND. WE TRIED TO DSND ASAP TO CATCH THE GS. THE GS STARTED TO MOVE OFF THE BOTTOM OF THE SCALE. AT ABOUT DOT FROM CAPTURING; THE GS JUST SHOT TO THE TOP OF THE SCALE AND THEN BACK TO THE BOTTOM SEVERAL TIMES. I ASKED THE FO TO SWITCH HIS SIDE TO VOR TO GET THE DME. I THINK THAT WAS AROUND 5-7 MI. I GOT INTERMITTENT GS FAIL FLAGS. AT APPROX 3 MI WE WENT AROUND. AGAIN; THE GS WAS ALL OVER THE PLACE WITH SAME FAIL FLAGS. ADDITIONALLY; IN THE GAR AND LEVEL OFF; WE WERE BOTH GETTING INTERMITTENT NAV FAIL LIGHTS. BOTH THE VOR AND ILS WERE GETTING GOOD IDENTS ALL THE TIME. I DECIDED TO EXERCISE THE CAPT'S EMER AUTH AND RETURN TO ZZZ. WE SWITCHED TO AUTOPLT #2 AND THE FO FLEW ILS WITH GS INTO ZZZ WHILE I WAS ON VOR WITH DME. JUST PRIOR TO INITIAL APCH INTO ZZZ; WE WENT THROUGH WHAT OTHER ACFT AND ATC CALLED MODERATE TO HVY RAIN AND SOME MODERATE TURB. AFTER SPEAKING WITH MAINT; WE SUSPECTED A LIGHTNING STRIKE OR STATIC DISCHARGE. WE HAD 9000 LBS OF FUEL.