A B727 FLC MADE AN AGGRESSIVE EVASIVE MANEUVER AFTER MISJUDGING THE PROX OF TFC NEAR CEW.

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I OBSERVED WHAT I BELIEVED TO BE AN IMMINENT TFC CONFLICT. I MANUALLY OVERRODE THE AUTOPLT AND STARTED AN IMMEDIATE L TURN. THE PERCEIVED CONFLICT WAS A RESULT OF PARALLAX OF GREEN AND RED WINGTIP LIGHTS OF ANOTHER ACFT. A BRIGHT WHITE STAR ALSO APPEARED AS ONE OF THE RUNNING LIGHTS ON THE PERCEIVED CONFLICT. THE MANEUVER WAS A GUT REACTION ON MY PART AS I PERCEIVED THE ACFT TO BE WITHIN A FEW THOUSAND FT FROM US. PAX AND FLT ATTENDANTS WHO WERE NOT SEATED WITH THEIR BELTS FASTENED WERE UPENDED IN THE CABIN. 1 PAX RECEIVED AN ABRASION TO A KNEE AND ONE COMPLAINED OF A NECK INJURY. BOTH PAX WERE EXTENSIVELY DEBRIEFED AFTER LNDG BY GND PERSONNEL AND NONE REQUIRED MEDICAL ATTN. THE EVENT DID NOT CAUSE AN ALTDEV AND WAS NOT A FACTOR IN OUR ATC CLRNC. THE ACFT WAS INSPECTED FOR OVERSTRESS AND NO DISCREPANCIES WERE FOUND. SUPPLEMENTAL INFO FROM ACN 451439: HIGHLY EXPERIENCED FO OBSERVED WHAT HE BELIEVED TO BE AN IMMINENT TFC CONFLICT. HE MANUALLY OVERRODE THE AUTOPLT TO TURN L. PAX AND CREW WERE STARTLED AS THIS WAS AN AGGRESSIVE MANEUVER. THE PERCEIVED CONFLICT WAS A RESULT OF MISINTERP OF THE ACTUAL DISTANCE BTWN US AND ANOTHER ACFT. THE FO REACTED BECAUSE HE THOUGHT THERE WAS A GENUINE SAFETY CONCERN AND COLLISION POTENTIAL. A PA WAS MADE EXPLAINING THE REASON FOR THE MANEUVER. THE FO NEVER DEVIATED FROM ASSIGNED ALT -- IMMEDIATELY REALIZED HIS MISJUDGEMENT AND WORKED WITH ME TO RETURN THE ACFT ON COURSE. NO RPT WAS MADE TO ATC BECAUSE NO CONFLICT EXISTED.