THIS LGT CREW WAS EITHER INVOLVED IN AN OPERROR OR THE CREW FLEW THROUGH THEIR ASSIGNED ALT CAUSING LTSS. NO FURTHER CONFLICT OCCURRED. ALL 3 CREW MEN THOUGHT THAT THEY WERE ASSIGNED FL210 VICE THE CTLRS CLAIM OF FL250. TCASII COMMANDED A DSCNT THAT THE AIRCREW FOLLOWED.

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I WAS FLYING AS THE RELIEF PLT ON FLT A; BOMBAY TO FRANKFURT; GERMANY. WE RECEIVED CLRNC TO CROSS ALB VOR AT FL250. THE FO INITIATED THE DSCNT. DURING THE DSCNT A FLT ATTENDANT ENTERED THE COCKPIT TO DELIVER SOME PAPERWORK. JUST AFTER THE FLT ATTENDANT DEPARTED; I HEARD 'TFC; TFC' ON TCASII. I OBSERVED TFC ON THE RADAR SCOPE AT APPROX THE 10:30 POS; 3 MI; AND 1400 FT BELOW OUR ALT. I STATED 'THE TFC IS 1400 FT BELOW US.' SHORTLY THEREAFTER; TCASII WARNED; 'MONITOR VERT SPD; CLB XING CLB.' AT THAT POINT; I BEGAN CALLING OUT THE ALT SEPARATION AT 800 FT. WHEN WE GOT TO 400 FT SEPARATION; WE VISUALLY ACQUIRED THE TFC WHICH PRESENTED A DEFINITE CONFLICT. THE CAPT DIRECTED THE FO TO INCREASE THE DSCNT RATE. WE PASSED BEHIND THE TFC BELOW AND BEHIND APPROX 1/2 MI. I NOTICED THAT WE HAD DSNDED THROUGH FL240 AND THE ALT BUG WAS SET AT FL210. THE CAPT THEN ASKED THE CTLR ABOUT THE TFC. THE CTLR STATED THAT THE TFC WAS AT FL240 AND WE HAD BEEN CLRED TO FL250. THE CAPT ASKED EVERYONE ABOUT OUR ALT CLRNC AND WE ALL AGREED THAT IT WAS FL210. (I BELIEVE WE WERE CLRED TO FL210; BUT DO NOT HAVE A CLR RECOLLECTION OF THIS EVENT). THE CTLR SUBSEQUENTLY CLRED US TO FL210.