CL60 HAD AN AIRSPACE INCURSION WITH AN MD80; FLYING PARALLEL SIMULTANEOUS APCHS TO RWY 26 AND RWY 27 AT IAH.

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THE CHALLENGER WAS EQUIPPED WITH TCASII AND DID NOT HAVE A TA. THE MD80 APPARENTLY DID HAVE A TA. DURING A FLT FROM OMA TO IAH; THE CREW MADE A SLIGHT DEV FROM THE RWY 26 APCH; WHICH WITH RWY 27 HAS SIMULTANEOUS ILS APCH AUTH. THERE WAS NEVER A POINT DURING THE APCH THAT THE ACFT EXCEEDED THE PROTECTED DEV AREA OF THE ILS APCH. THE NARROW SEPARATION DISTANCE BTWN THE 2 APCHS OF 1 MI AND THE PROX OF ANOTHER ACFT ON THE RWY 27 APCH PROMPTED A TARGET ALERT ON THE OTHER ACFT. BUT DID NOT CAUSE A TARGET ALERT ON THE CHALLENGER. SEQUENCE OF EVENTS: THE CREW OF THE CHALLENGER WAS GIVEN A R TURN TO 260 DEGS; CLRED FOR APCH AND CONTACT TWR. THE CAPT ACKNOWLEDGED THE CLRNC AS THE COPLT WAS ENGAGED IN OTHER COCKPIT DUTIES. THE ACFT WAS ON AUTOPLT SO THE CAPT TURNED THE HDG BUG TO 260 DEGS AND ENGAGED THE APCH MODE ON THE FLT DIRECTOR. AT THAT POINT THE CAPT WAS CONCERNED BECAUSE THE ASSIGNED HDG APPEARED TO BE TOO SHALLOW TO INTERCEPT THE ILS COURSE BEFORE THE OM. THE CDI INDICATOR WAS SHOWING FULL DEFECTION L. THE HDG WOULD HAVE BEEN FINE IF THE ACFT WAS ON OR ALMOST ON COURSE. AT THIS POINT THE CAPT LOOKED AT THE FMS EXTENDED CTRLINE FROM THE OM ON THE MFD WHICH SHOWED THAT THE ACFT WAS ON COURSE FOR THE ILS RWY 26. THE CAPT AGAIN CHKED THE CDI AND IT WAS STILL FULL DEFLECTION L. AT THIS TIME THE CAPT SAID TO THE COPLT; 'THIS IS NOT RIGHT; THE FMS DOES NOT AGREE WITH THE ILS.' THE COPLT CHKED THE APCH CHART AND SAID; 'I GAVE YOU THE FREQ FOR RWY 27.' HE CHANGED THE CAPT'S ILS FREQ. THE CAPT IMMEDIATELY TURNED THE HDG BUG TO 280 DEGS SO THE ACFT WOULD INTERCEPT THE RWY 26 LOC. AT THE SAME TIME; THE CAPT SAW A WHITE DC9 AT ABOUT 10 O'CLOCK LOW AND NOTED THAT IT APPEARED TO BE STARTING A LEVEL L TURN. THE DISTANCE LOOKED TO BE OVER 1 MI AHEAD AND ABOUT 800-1000 FT LOWER. THE CHALLENGER'S ALT WAS ABOUT 3500 FT AT THE COMPLETION OF THE TURN. THE CAPT ALSO NOTED THAT THE GS INDICATOR WAS CTRED AND THE CDI WAS 1/2 DEFLECTION TO THE R SO HE CONTINUED THE APCH FOR RWY 26. APCH CTL CAME ON THE FREQ AND ASKED IF WE WERE ON FREQ. THE COPLT ACKNOWLEDGED THE CALL. THE CTLR SAID TO LEVEL AT 3000 FT WHICH THE CAPT DID. THE CAPT TOLD THE COPLT TO RPT SEEING THE OTHER ACFT AND THAT THE ARPT WAS IN SIGHT. AT THIS TIME THE ACFT APPEARED TO BE SLIGHTLY L OF RWY 26 CTRLINE AND THE CDI WAS LESS THAN 1/2 DEFLECTION. THE COPLT ACKNOWLEDGED THAT THE ARPT WAS IN SIGHT AND TOLD APCH CTL WHICH TOLD THE CREW TO CONTACT TWR. THE COPLT TOLD THE TWR THE ARPT WAS IN SIGHT; AT WHICH TIME THE TWR CLRED THE ACFT FOR A VISUAL APCH. CONCLUSION: THE CREW OF THE CHALLENGER ERRED IN NOT PUTTING THE CORRECT ILS FREQ IN THE NAV RADIO; BUT WERE ABLE TO CORRECT THE MISTAKE BEFORE THEY EXCEEDED THE LIMITS OF THE ILS. THE SIMULTANEOUS ILS APCH TO IAH FOR RWY 27 AND RWY 26 ARE ONLY 1 MI APART. THE PROTECTED AREA OF BOTH ILS APCHS OUTSIDE THE OM'S CROSS INTO THE OTHER'S PROTECTED BOUNDARY. BECAUSE OF THIS; AUTH FOR SIMULTANEOUS APCH OPS HAVE SPECIAL RULES. BOTH ACFT WILL MONITOR THE SAME FREQ AND IF THE GND CTLR DETECTS A DANGEROUS SIT THE ORDER TO BREAK OR DISCONTINUE THE PLTS OF BOTH ACFT ARE OBLIGATED TO BREAK OFF THEIR APCH AND TURN IN APPROPRIATE DIRECTION. THE L APCH BREAKS L; THE R BREAKS R. THIS MONITORING SHOULD BE ON BOTH APCH FREQ AND TWR. IN THIS CASE THE TWR WAS THE ONLY COMMON FREQ. IT WOULD BE PRUDENT FOR ARPT CTLRS TO MAKE SURE BOTH ACFT ARE ON THE SAME APCH FREQ AS WELL AS THE TWR FREQ. THE CHANCE THAT THE 2 ACFT WILL HAVE PREMATURE TFC ALERTS; AS ONE OF THESE ACFT HAD; IS MORE LIKELY WHEN THE ACFT ARE HDG IN OPPOSITE DIRECTIONS FOR A MOMENT DURING THEIR FINAL TURN INBOUND DURING THE APCH. IT IS MUCH LESS CHANCE OF A FALSE ALERT OR A REAL CONFLICT ONCE BOTH ACFT ARE ON THEIR INBOUND COURSE. ANOTHER CHANGE IN PROC WOULD BE TO HAVE INFORMED BOTH ACFT OF THE OTHER BEFORE THE APCH BEGINS. IN THIS SIT; NEITHER ACFT WAS INFORMED OF THE OTHER. IF A FALSE TFC ALERT ACCRUES AND THE CREW CAN IDENT AND VERIFY THE PRESENCE OF THE OTHER VISUALLY; THE TA CAN BE JUST A WARNING AND NOT A DEV. SUPPLEMENTAL INFO FROM ACN 412031: THE CAPT NOTICED THAT THE LOC NEEDLE DEFLECTION AND THE RWY 26 COURSE CTRLINE THAT WAS PROGRAMMED INTO THE SPERRY FMS DID NOT AGREE. I IMMEDIATELY CHKED ALL THE NAV FREQS AND FMS SET-UP CONFIRMING THE ERROR WAS WITH THE WRONG ILS FREQ SET IN. I HAD BOTH RWY 27 AND RWY 26 ILS FREQS PREPROGRAMMED.