MD80 FLT CREW REPORTS GPWS WARNING DURING ILS TO 9R AT ORD IN ICING CONDITIONS AND SUBSEQUENT MISSED APPROACH. SECOND APPROACH WITH FO FLYING USING NUMBER TWO AUTO PILOT IS SUCCESSFUL.

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I WAS FLYING INTO ORD. THE WX WAS THICK OVCST LAYER OF CLOUDS; CLR ABOVE AND LIMITED VISIBILITY BELOW. THERE WAS RIME ICING IN THE CLOUDS. THE FLT WAS NORMAL ALL THE WAY AND WE WERE GIVEN RWY 9R ILS BY ORD APCH. WE WERE GIVEN A HDG TO INTERCEPT OUTSIDE OF DEVON AND TOLD TO MONITOR TWR WHEN WE WERE ESTABLISHED ON THE LOC AND CONTACT TWR AT LANSE. WE WERE ALSO GIVEN A MINIMUM SPD TO LANSE. THE LOC WAS ARMED AND THEN CAPTURED. INSTEAD OF DSNDING AT DEVON I ELECTED TO CAPTURE THE GS AND FOLLOW IT DOWN. ALL ICE PROTECTION WAS ON. AFTER DEVON; ON AUTOPLT; WITH BOTH LOC AND GS CAPTURED; I SWITCHED FROM ROSE TO MAP TO SEE HOW FAR FROM LANSE I WAS SO I COULD ADJUST MY SPD ACCORDINGLY. SHORTLY AFTER THAT; JUST OUTSIDE LANSE; WE GOT THE RED LIGHT AND 'TERRAIN; TERRAIN; PULL UP.' THIS CONFUSED BOTH OF US BECAUSE ALTIMETERS; LOC AND GS APPEARED TO READ NORMAL. IN FACT; THE FO SAID 'THIS MUST BE JUST AN INDICATION PROB BECAUSE ALL IS NORMAL.' AFTER A SHORT TIME WE THEN GOT 'GS; LNDG GEAR.' I SAID 'LET'S GO AROUND.' AT THIS TIME THE RADIO ALTIMETER WAS READING 500 FT. I PRESSED TOGA AND FOLLOWED THE V-BARS IN CLB. MY HDG WAS ALWAYS INDICATING BTWN 080-090 DEGS. WHAT WAS CONFUSING WAS THE CTLR DIDN'T SEEM TO BE ACKNOWLEDGING OR EVEN REGISTERING THE FO'S STATEMENT THAT WE WERE GOING AROUND BECAUSE OF A GPWS WARNING. WE WERE TOLD TO CLB TO 4000 FT WHICH I WAS ALREADY THROUGH BUT EASILY GOT BACK TO. THE CTLR SAID TO TURN TO A HDG AND INTERCEPT THE LOC. HE SAID THIS ABOUT 3 TIMES. THIS INSTRUCTION CONFUSED ME MORE BECAUSE I SHOWED US ALREADY ON COURSE AND ON ALT. HE THEN SAID THAT IF WE COULDN'T INTERCEPT; TO TURN L TO 320 DEGS; WHICH I DID. THINGS SEEMED TO SETTLE DOWN THEN AND WE WERE VECTORED AROUND FOR THE ILS RWY 9R APCH AGAIN. I ELECTED TO HAVE THE FO FLY THE APCH THIS TIME AND PUT THE AUTOPLT TO #2. ALL WAS NORMAL EXCEPT FOR MY RA BOUNCING UP AND DOWN FULL SCALE. LOC AND GS WERE CAPTURED AND ON THE DSCNT THE FO'S RA STARTED BOUNCING UP AND DOWN. AUTOPLT CLICKED OFF AND LOC TRACK; GS TRACK WENT AWAY. ALTHOUGH THE HDG LIGHT HAD COME AND GONE EARLIER IN THE FLT ON THE FMA; I DON'T REMEMBER SEEING IT ON DURING THIS APCH BUT I DO REMEMBER SEEING THE 'NO AUTOLAND' LIGHT. I TOLD THE FO TO FLY RAW DATA AND WE COMPLETED THE APCH. I RECALL THAT AFTER LNDG THERE WAS A GREAT DEAL OF ICE ON THE ACFT IF THAT IS OF IMPORTANCE. ON POSTFLT INSPECTION; THE FO RPTED ICE ON THE ANTENNAE. ALSO (AND I DIDN'T THINK OF THIS UNTIL LATER SO I DIDN'T PUT THIS IN THE LOGBOOK) BUT IT SEEMED THAT ALL INDICATIONS STAYED NORMAL UNTIL THERE WAS A PITCH CHANGE FOR GS. BECAUSE OF RADIO ALTIMETER FAILURE AND PREVIOUS COMPASS PROBS; MAINT TOOK THE AIRPLANE OTS.