ALTDEV ALT OVERSHOT IN CLB PRODUCES AN NMAC.

Narrative

BASED ON CURRENT WX CONDITIONS AND ATIS INFO; A KIR2F SID RWY 25 (5000 FT LEVEL OFF ALT) WAS FILED OUT OF THE FRANKFURT ARPT. AN AIRBORNE SLOT TIME OF PM20 TO PM35 WAS ASSIGNED. LATE ARR OF THE PUSH BACK EQUIP WAS DELAYING OUR PUSH TIME. THE EXPECTED AND FILED SID WAS BRIEFED PRIOR TO RECEIVING ATC CLRNC BECAUSE ONCE THE EQUIP ARRIVED; I KNEW THAT WE WOULD BE RUSHED. THE FLT GUIDANCE WAS PROGRAMMED ACCORDINGLY. GND CTL WAS ASKED IF A NEW SLOT TIME WAS NEEDED; AND WE WERE INFORMED THAT WE 'SHOULD' BE ABLE TO MAKE OUR DEP WINDOW. ATC CLRNC WAS RECEIVED; A KIR2L SID; INDICATING OUR DEP RWY WAS NOW 18 (4000 FT LEVEL OFF ALT). WE STARTED OUR PUSH START AT PM20. AT PM30; RAMP CTL CLRED US TO RWY 18 AND IMMEDIATELY SWITCHED US TO TWR WHO CLRED US TO 'LINE UP AND WAIT; AND BE READY TO TKOF AS SOON AS THE ACFT LNDG ON A XING RWY HAD LANDED.' DURING THE SHORT TAXI AND LINE UP; 3 CHKLISTS WERE COMPLETED AND THE NEW SID WAS DISCUSSED. THE HDG BUGS; COURSE SELECTORS; AND RADIOS WERE RESET; BUT IN THE RUSH; NO ONE RESET THE ALT ARM/ALERTER TO 4000 FT. THE ACFT WAS EXTREMELY LIGHT AND FULL PWR WAS USED DUE TO WX CONDITIONS (10 OVCST 3 S-). ACFT CLBED QUICKLY AND BY THE TIME THE ACFT WAS CLEANED UP AND FRANKFURT DEP WAS CALLED; THE FLT GUIDANCE WAS ALREADY IN THE ALT CAPTURE MODE FOR 5000 FT AND I BEGAN TO LEVEL OFF. THE CTLR TOLD US THAT WE SHOULD BE AT 4000 PER THE SID AND THAT WE CAME VERY CLOSE TO ANOTHER ACFT. ANTICIPATED AND FILED DEP BEING CHANGED; EQUIP DELAY AND RAPIDLY APCHING SLOT TIME; ALONG WITH SHORT TAXI; AND EXCEPTIONAL ACFT PERFORMANCE WERE ALL CONTRIBUTING CAUSES. FRANKFURT HAS MANY SIDS WITH DIFFERENT INITIAL ALTS; ADDING TO THE CONFUSION. TCASII WOULD HAVE BEEN INVALUABLE IN THIS SITUATION!