CLOSE PROX ACR-MLG GA-UNK ABOVE N90 TCA.

Narrative

WHILE ON DSCNT FROM 11000' WITH CLRNC TO 7000'; WAS ISSUED 'VFR TFC AT 12 O'CLOCK.' ALT 8500'; UNVERIFIED; WBOUND. PNF (CAPT) SPOTTED TFC AND WAS FORCED; AT TFC ACQUISITION; TO TAKE CTL OF ACFT AND DIVE BELOW CONFLICTING TFC. OTHER ACFT; WITH LNDG LIGHT ON; WAS NOT PARTICIPATING IN VFR ADVISORY. WE WERE ABLE TO LEVEL AT 7000' BUT VERT SPD APCHED 6000 FPM RATE OF DSCNT. THE CONFLICTING TFC WAS MASKED INITIALLY BY THE BACKGROUND CITY LIGHTS OF NY DUE TO THE DSCNT ANGLE. ALSO WE TRIED TO ADVISE APCH CTL OF THE ACFT'S ALT POS; BUT UNACKNOWLEDGED FOR APPROX 6-8 FLYING MI. THE EVASIVE MANEUVER CAUSED NUMEROUS DISTURBANCES IN PAX MEAL SVC AND CAUSED THE F/A'S (IN THE AISLE COLLECTING THE MEALS) TO LOSE BALANCE. ATTEMPTS TO ADVISE ATC OF NEAR MISS WAS VERY DIFFICULT BECAUSE OF ATC TFC LOAD. THIS SITUATION EVOLVED DUE TO SEVERAL FACTORS: DSCNT ANGLE OF ACFT LOOKING DOWN AT CONFLICTING TFC WHICH BLENDED INTO BACKGROUND LIGHTS; AND IN CREW'S OPINION LGA/NY TCA CEILING IS TOO LOW (IE; 7000'). A CHANGE IN COURSE HDG AND LEVEL OFF MIGHT HAVE PREVENTED SUCH A CLOSE ENCOUNTER.