MLG FLC INBOUND TO CRP WERE CLRED FOR A VISUAL APCH TO RWY 31. THE FLT PATH FOR THIS APCH CROSSES OVER CABANISS FIELD. THE APCH CTLR DID NOT RESTRICT THE ALT OF THE FLT OVER THE FIELD ADJACENT TO CRP.

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OUR FLT DEPARTED HOUSTON HOBBY ARPT AND ARRIVED AT CORPUS CHRISTI INTL ARPT. ENRTE; ZHU CLRED THE FLT TO DSND TO 11000 FT AND CONTACT CRP APCH CTL. CRP WX WAS RPTED AS CLR SKIES; VISIBILITY 10 MI AND THE WINDS WERE FROM A NE DIRECTION AT 4 KTS. CRP APCH CTL WAS CONTACTED AND AN APCH TO RWY 17 WAS REQUESTED. APCH CTL SAID THAT HE WOULD CHK ON THAT AND CLRED THE FLT TO DSND TO 6000 FT. APCH CTL SUBSEQUENTLY SAID TO EXPECT RADAR VECTORS FOR A VISUAL APCH TO RWY 35 AND GAVE US A HDG OF 210 DEGS. XING THE CORPUS CHRISTI BAY APPROX 7 MI NE OF THE ARPT; APCH CTL GAVE US A HDG OF 180 DEGS AND A DSCNT TO 3000 FT. APCH CTL ASKED IF WE HAD THE FIELD IN SIGHT (OR WE CALLED THE FIELD IN SIGHT) AND ASKED IF WE COULD TAKE A VISUAL APCH TO RWY 31. WE REPLIED AFFIRMATIVELY AND APCH CTL CLRED US FOR A VISUAL APCH TO RWY 31. APCH CTL ASKED IF WE WERE FAMILIAR WITH THE CABANISS OP AND THE CAPT RESPONDED HE KNEW WE WERE NOT TO MISTAKENLY LAND THERE. APCH CTL THEN CLRED US FOR THE VISUAL APCH TO RWY 31 AND TOLD US TO CONTACT CRP TWR. WE WERE DSNDING THROUGH 5000 FT AND BEGAN CONFIGN FOR LNDG; AND PLACED 2000 FT IN THE ALT SET WINDOW. A SLOW DSNDING TURN TO FINAL APCH WAS MADE. WE REQUESTED TWR TURN UP THE RWY LIGHTS; WHICH THEY DID; AND TWR CLRED US TO LAND ON RWY 31. AN ACFT WAS OBSERVED APPARENTLY ON TKOF FROM CABANISS FIELD AND ENTERING A L DOWNWIND HDG S AND TO THE W OF CABANISS FIELD WHILE WE WERE IN THE TURN TO FINAL AT APPROX 2300 FT MSL. IT WAS DECIDED TO LEVEL OFF AS WE WERE NOW ON FINAL APCH TO RWY 31 PASSING OVER THE CABANISS FIELD AREA. AFTER PASSING THE APPARENT CABANISS FIELD RWY ANOTHER ACFT WAS IDENTED TURNING DOWNWIND BELOW AND PASSING AFT OF OUR FLT PATH; AND NO AVOIDANCE MANEUVER WAS NECESSARY BY EITHER ACFT TO MAINTAIN APPROPRIATE SEPARATION. NO TCASII INFO WAS DISPLAYED FOR THE ACFT IN THE CABANISS FIELD PATTERN. AFTER PASSING THIS ACFT; FURTHER DSCNT WAS INITIATED AND IT WAS NOTED THAT WE WERE AT 1800 FT AT 3.5 NM FROM CRP RWY 31 ON THE FINAL APCH. LNDG WAS UNEVENTFUL. AFTER LNDG; WHILE DEPARTING THE RWY; THE CAPT MADE A REMARK TO TWR CONCERNING ACFT IN THE FINAL APCH AREA AND TWR RESPONDED THAT IS WHY THERE IS A 2000 FT RESTR UNTIL 5 MI WHEN LNDG CRP RWY 31. THE CAPT RESPONDED HE WAS UNAWARE OF THAT RESTR AND TWR STATED THAT APCH CTL WAS SUPPOSED TO TELL US. WHILE THERE WAS NO COLLISION AVOIDANCE NECESSARY TO MAINTAIN SEPARATION AND THE FLT STAYED HIGHER THAN A NORMAL APCH TO AVOID CABANISS TFC. RECOMMEND SPECIFIC WRITTEN ALT RESTRS OR A DEPICTED VISUAL APCH TRACK AND ALT BE PLACED ON ARRS TO CRP RWY 31 WHEN CABANISS FIELD IS BEING USED. RECOMMEND IT BE DISSEMINATED TO ALL USERS IN A PERMANENT FASHION SO THAT AIR CREWS WOULD BE AWARE OF POTENTIAL AIR TFC TO THE W OF CABANISS FIELD AND POSSIBLE STEEP DSCNT REQUIRED; AND PLAN ACCORDINGLY. THIS IS AN UNUSUAL SIT AS CRP APCH AND TWR CLR YOU TO FLY THE APCH AND LAND CRP RWY 31 WHILE FLYING THROUGH CLASS D AIRSPACE OF CABANISS FIELD APPROX 5 MI ON FINAL FROM CRP WHILE IN CRP CLASS C AIRSPACE.