DC8-63 ACFT ON APCH HAD NMAC WITH A C172 WHO WAS HAVING COM DIFFICULTY. TWR HAD TRIED TO CONTACT THE CESSNA; BUT UNABLE. AS A RESULT; IT FLEW ACROSS THE PATH OF THE DC8. RPTR CAPT PUSHED OVER TO FLY UNDER THE CESSNA.

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ON APR/XA/98 DURING THE APCH PHASE TO RWY 30 AT LGB; A NEAR MISS OCCURRED BTWN MY DC8 AND A C172. THE CESSNA CROSSED FROM E TO W ACROSS MY DIRECTION OF FLT AT THE SAME ALT OF 1600 FT MSL NEAR THE BECCA NDB. MY ACFT WAS ON LOC AND INTERCEPTING THE GS AND CLRED FOR THE APCH BY SOCAL APCH. APCH WARNED OF TFC AT 12-1 O'CLOCK; SAME ALT. UPON SEEING THE TFC; I INCREASED THE DSCNT TO PASS BELOW THE CESSNA. I ESTIMATED THE VERT SEPARATION TO BE 200-300 FT. UPON LNDG; I CALLED THE TWR TO GET ANY INFO AVAILABLE ON THE CESSNA AND WAS ADVISED (VIA PHONE) BY THE TWR OPERATOR THAT THE OTHER ACFT WAS UTILIZING RWY 25L; HAD PARTIAL RADIO; AND WHEN THE TWR HEARD THE CESSNA PLT; ADVISED HE WAS GOING TO TURN S AND THEN RE-ENTER THE PATTERN FOR RWY 25L. THERE WAS A CONFLICT POSSIBILITY SINCE WE HAD JUST COME UP ON THE TWR'S SCREEN. HE IMMEDIATELY CALLED APCH TO WARN OF THE PROB. THE HEADS UP REACTION BY TWR CALLING APCH HELPED IN THIS SIT ONLY BEING A NEAR MISS. THE TWR OPERATOR ALSO TOLD ME THAT HE SAW THE NEAR MISS FROM HIS POS AND VERIFIED THE VERT SEPARATION OF 200-300 FT.