MLG TAXIING TO GATE WITH MARSHALLER HAS WING TIP OF ACFT ON PUSHBACK AT NEXT GATE.

Narrative

AFTER LNDG AT STL; WE WERE TAXIING INTO GATE A. EVERYTHING WAS UNEVENTFUL UNTIL AFTER BEING LINED UP ON THE LEAD-IN LINE. AT THAT TIME I NOTICED THAT THE ACFT AT GATE B WAS BEGINNING ITS PUSH BACK. NO CONFLICT EXISTED AT THAT TIME AND I SURVEYED GATE A'S SAFETY ZONE (FROM R TO L). THE SAFETY ZONE WAS COMPLETELY CLR. I THEN BEGAN TO SURVEY THE AREA FROM L TO R AND AS I LEANED UP IN MY SEAT AND TURNED TO THE R TO LOOK AT THE WING TIP AREA; I SAW A CONFLICT WITH THE OTHER WING-TIP; AND SIMULTANEOUSLY TO MY STARTING TO CALL FOR STOP; THE WING TIPS COLLIDED AND THE CAPT STOPPED IMMEDIATELY. AS FAR AS I KNOW; THE ACFT WAS STILL PUSHING BACK. AS I TURNED BACK TOWARD THE FRONT OF THE ACFT; I SAW THE MARSHALLER GIVING THE SIGN FOR HOLD. I INFORMED THE CAPT THE WING TIPS HAD COLLIDED. AFTER THAT; I ASSISTED THE CAPT IN GETTING THE ACFT TOWED TO THE GATE AND THE PAX ON THEIR WAY. THE REASON THIS PROB PROBABLY OCCURRED WAS BECAUSE THESE 2 SAFETY ZONES HAD BEEN RE-ALIGNED WITH XING SAFETY ZONES. THIS CHANGE WAS NOT KNOWN BY MYSELF OR THE CAPT. PRIOR KNOWLEDGE PROBABLY WOULD HAVE KEYED US TO AN IMPENDING CONFLICT ON TAXIING IN AND DEFINITELY WHEN THE OTHER ACFT BEGAN TO PUSH BACK.