FLC OF A CPR EXECUTIVE JET DSNDED EARLY ON A GPS APCH RESULTING IN TWR CTLR ALERTING THEM WHEREUPON THEY ALSO RECOGNIZED THEIR MISTAKE AND COMMENCED A MISSED APCH.

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DSCNT INTO CHICAGO AREA A DECISION WAS MADE TO MAKE THE GPS APCH TO RWY 5 INTO WAUKEGAN OUR DEST. THE REASON FOR THIS WAS THE TAILWIND OF ABOUT 8-10 KTS OUT OF THE NE AND ALSO A WET RWY. WAUKEGAN ATIS RPTING CEILING 8 BROKEN 2 1/2 WIND 8-10 KTS FROM 050 DEGS; LIGHT MIST AND FOG; ILS RWY 23 APCH LNDG RWY 20; DEPARTING RWY 5. ZAU WAS INFORMED THAT WE WANTED THE GPS TO RWY 5 AT WAUKEGAN. THIS WAS ACKNOWLEDGED BY THE CTLR. WE TURNED OVER TO MILWAUKEE APCH. MILWAUKEE GAVE US ALT CHANGE AND HEADING FOR ILS RWY 23 AT WAUKEGAN. I INFORMED MILWAUKEE WE WANTED THE GPS. MILWAUKEE THEN TURNED US OVER TO CHICAGO AREA APCH. CHICAGO GAVE US VECTORS FOR THE ILS RWY 23 AT WAUKEGAN. I INFORMED THE CTLR THAT WE WANTED THE GPS. HE GAVE US A HEADING AND TO KEEP OUR SPD TO 200 KTS WE WOULD BE #1. WE WERE ASKED IF WE HAD THE NEW ATIS AT WAUKEGAN. I TUNED TO GET THE ATIS. IT WAS NOT UP YET ON THE TAPE. I INFORMED THE CTLR THAT WE DIDN'T HAVE IT. HE READ IT TO US. IT HAD IMPROVED TO 10 BROKEN VISIBILITY 3 MI. OUR SPD HAD DROPPED TO 180 KTS. THE CTLR ASKED OUR SPD. I TOLD HIM 180 KTS. HE SAID THAT IF WE WANTED TO BE #1 TO KEEP OUR SPD 200 KTS OR BETTER. WE WERE GIVEN A HEADING INTERCEPT INBOUND LEG HOLD 2500 FT TILL ESTABLISHED AND CALL TWR. TWR WAS IN A CONVERSATION WITH AN ACFT THAT HAD BEEN WAITING TO DEPART. THE PLT WAS COMPLAINING ABOUT THE DELAY AND HELD SO LONG ON THE GND. WE FINALLY GOT ACKNOWLEDGMENT FROM THE TWR. DURING THE APCH THE INITIAL FIX WAS MISREAD AND DSCNT WAS STARTED TOO SOON. TWR ASKED US OUR DISTANCE FROM THE ARPT AND WE THEN REALIZED THAT THE APCH WAS WRONG AND INFORMED THEM WE WERE ABANDONING THE APCH. WE WERE TOLD TO CLB TO 2500 FT TURN TO HDG 090 DEGS; CALL CHICAGO APCH. CHICAGO VECTORED US FOR THE ILS APCH. WE LANDED OUT OF THAT APCH. I THINK FACTOR AFFECTING THE QUALITY OF HUMAN PERFORMANCE WAS THE WORKLOAD OF CHANGING FROM MILWAUKEE APCH TO CHICAGO APCH AND NEITHER FACILITY NOT KNOWING WHAT APCH WE WANTED. THE WORKLOAD OF THE CTLR; THE DISTR OF THE TWR FREQ BEING TIED UP.