LATE MODIFICATIONS TO FMC PERFORMANCE DATA WHILE HOLDING IN POSITION FOR TKOF MAY HAVE RESULTED IN ERRONEOUS THRUST SETTINGS FOR DEP FROM ORD FOR B777 FLT CREW. MAY NOT HAVE MET CROSSING RESTRICTION AT EIGHT DME.

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ON INITIAL CLB ACFT PWR SETTING OF TO2 WAS NOT SUFFICIENT TO MAKE ORD 4000 FT MSL BY 8 DME RESTR. ATC COMMENTED ON SLOW CLB AT APPROX 6.5 DME. HIGHER CLB PWR WAS SELECTED AND WE BELIEVE THAT WE CLRED THE 5 BY 8 DME RESTR. DEP WAS PLANNED AND BRIEFED FOR ORD; RWY 32R. 10005 FT AVAILABLE RWY. RWY WAS DRY. DAY VFR FLT CONDITIONS. TKOF WAS PLANNED AND BRIEFED AS STANDARD PWR; TO2 WITH AN ASSUMED TEMP OF 26 DEGS C. START AND TAXI WERE NORMAL. DURING TAXI; CREW REQUESTED AND RECEIVED NEW PERFORMANCE NUMBERS VIA ACARS. DATA WAS BASICALLY UNCHANGED; EXCEPT FOR A 1 DEG CHANGE (TO 30 DEGS) IN ASSUMED TEMP (AT). BUGS AND PWR WERE INSERTED AND VERIFIED AGAIN. APCHING THE #1 POS FOR RWY 32R WE INFORMED THE TWR CTLR THAT WE WERE NOT YET READY FOR TKOF; SINCE WE HAD NOT RECEIVED OUR LOAD CLOSEOUT. THE CTLR REPLIED; 'THAT'S OK; I STILL NEED YOU TO HOLD IN POS ON RWY 32R.' WE ACCEPTED THAT CLRNC TO HOLD IN POS; BASED ON INFO THE RELIEF PLT (WHO HAD BEEN COMMUNICATING WITH THE LOAD ROOM) THAT LOAD CLOSEOUT WOULD BE READY SHORTLY. RWY 32R WAS NOT BEING USED FOR APCHS. AFTER A SHORT WAIT; THE LOAD CLOSEOUT WAS RECEIVED ALONG WITH A NEW FMC UPLINK OF TKOF DATA. SINCE OUR NUMBERS WERE BASICALLY UNCHANGED; WE ACCEPTED THE NEW UPLINKED TKOF DATA. SHORTLY THEREAFTER WE RECEIVED TKOF CLRNC. DURING TKOF ROLL THE CAPT; WHO WAS FLYING; DECIDED HE DID NOT LIKE THE THRUST SETTING AND INCREASED THRUST TO TKOF (FULL PWR). TKOF WAS CONTINUED UNEVENTFULLY. AFTER TKOF WE DISCUSSED THE EVENT AND CONCLUDED THAT OUR THRUST WAS LOWER THAN IT SHOULD HAVE BEEN. WE SURMISED THAT THE ASSUMED TEMP HAD CHANGED; AND WE DID NOT CATCH IT. UNFORTUNATELY; THE FMS DELETES THE TKOF THRUST SETTINGS USED IMMEDIATELY AFTER TKOF; AND WE WERE UNABLE TO REVIEW THE DATA WE USED AFTER THE EVENT. THIS WAS A VERY EXPERIENCED CREW. NONETHELESS; WE MISSED AN IMPORTANT CHK. ALTHOUGH OUR DATA WAS VIRTUALLY UNCHANGED; THE LAST FMC UPLINK OF THE TKOF REF DATA APPARENTLY INTRODUCED A CHANGE AND AN ERROR. THIS IS WHAT WE MISSED. IN OUR COCKPIT DEBRIEF THE RELIEF PLT MENTIONED THAT HE HAD NOT RECEIVED A TKOF DATA UPLINK DURING THE PREFLT LOADING OF THE FMS. KNOWING THIS; WE SUSPECT THAT THE DATA THAT WAS UPLINKED MAY HAVE BEEN FROM THE PREVIOUS (DOMESTIC) LEG. THIS PROB WAS ADDRESSED LAST YEAR IN A BULLETIN AS A CAUTION. ALTHOUGH THE PREVIOUSLY MENTIONED CAUTION REFERS TO PARTIAL UPLINKS; WE ALL CONCUR THAT THE UPLINK WE RECEIVED DID NOT APPEAR TO BE INCOMPLETE AND THEREFORE THE CAUTION WOULD NOT HAVE APPLIED.