EMB170 WAS CLEARED FOR A VISUAL APCH; BUT INITIATED APCH INTO NEARBY ARPT WITH SIMILAR RWY CONFIGURATION. THE ERROR WAS DISCOVERED; AND AN APCH WAS CONDUCTED TO THE DEST ARPT.

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HOUSTON APCH CTL CLRED US FOR A VISUAL APCH TO RWY 4 IN HOU AS WE WERE ON DOWNWIND. WE WERE HANDED OFF TO HOU TWR AND WERE CLRED TO LAND ON RWY 4. WE TURNED BASE LEG ABOUT 6 MI AND SAW ELLINGTON ARPT WHICH ALSO HAS A RWY 4. AT 1700 FT MSL WE REALIZED WE WERE LOOKING AT ELLINGTON AND COMPARED WHAT WE SAW VISUALLY TO THE MFD AND THE EXTENDED COURSE FROM HOU RWY 4; AND ALSO THE LOC COURSE; AND REALIZED IT WASN'T LINING UP CORRECTLY. AT APPROX 1600 FT MSL THE TWR INSTRUCTED US TO TURN TO A HDG OF 270 DEGS AND CLB TO 2000 FT AND THAT THE FIELD WOULD BE AT OUR 2 O'CLOCK POS. WE WERE ASKED TO RPT THE FIELD IN SIGHT. WE COMPLIED WITH THE INSTRUCTION; OBTAINED VISUAL ON THE FIELD; WERE CLRED TO LAND AND LANDED ON RWY 4 AT HOU; WITHOUT INCIDENT. THANKS TO GOOD CRM; BACKING UP THE APCH WITH THE LOC; AND LOADING THE APCH IN THE FMS FOR SITUATIONAL AWARENESS; AN INCIDENT WAS AVOIDED. WE THINK A POSSIBLE SAFETY RISK EXISTS AND CREWS SHOULD BE EXTREMELY VIGILANT; ESPECIALLY AT NIGHT; WHEN COMMENCING VISUAL APCHS AT HOU TO RWY 4; BECAUSE ELLINGTON ARPT IS APPROX 4 MI FROM HOU WITH THE SAME RWY CONFIGN.