A B737-800 CAPT RPTS A LATE; HURRIED DEP. TRYING TO PREVENT FURTHER DELAY; AN ACARS TEMP ERROR ENTRY (30 DEGS F VERSUS 88 DEGS F) ALLOWED AN OVERWT TKOF BECAUSE OF A CELSIUS VERSUS FAHRENHEIT ERROR.

Narrative

WE WERE AT MCO. OUR WT AND BAL SAID WE WERE OVERWT FOR A TKOF TO THE S. WE ADVISED GND. THEY WERE NOT HAPPY; SAYING VERY EXTENSIVE DELAY. MCO WAS LNDG S WITH AN 8 KT TAILWIND. I FELT HURRIED AS WE WERE ALREADY 45 MINS LATE DUE TO A PRESSURE CONTROLLER FAILURE. LCL GND MCO; THREATENING EXTENSIVE DELAYS; I ELECTED TO INPUT NEW DATA THROUGH THE ACARS TO REFLECT CURRENT XWIND VERSUS TAILWINDS; TO SEE IF A S DEP WAS POSSIBLE. MY FO WAS INPUTTING THE DATA INTO THE ACARS. WHEN IT CAME TO TEMP; WE INPUTTED 30 DEGS C. THE ACARS WANTED FAHRENHEIT. SO NOW THE LOAD PLANNING COMPUTER THINKS IT'S 30 DEGS F INSTEAD OF 88 DEGS F. IT SPIT OUT A NEW WT AND BAL; GIVING US S DEP PERFORMANCE. WE LOADED IT IN THE FMS AND OFF WE WENT. OH THAT FEELING THAT DOESN'T GO AWAY WHEN YOU CHK AND RECHK; BUT STILL AIN'T SURE. ABOUT 1/2 WAY TO SLC; I LOOKED AT THE NEW WT AND BAL FROM THE ACARS. THERE IT WAS IN BLACK AND WHITE. 'ATTN AIR CREW; HUGE TEMP CHANGE. VERIFY INPUT IN FAHRENHEIT VERSUS CELSIUS.' I LOOKED AT THAT WT AND BAL AT LEAST 10 TIMES WHILE INPUTTING IT INTO THE FMS. LOOKED BUT DIDN'T SEE. I KNEW SOMETHING WASN'T RIGHT; I CHKED AND CHKED AGAIN; GAVE IT TO THE FO TO CHK. WOW! SO HERE IT IS: BAD. 1) GOT IN A HURRY. 2) LET GND CTL PUSH ME AROUND. 3) FAILED TO PROPERLY SUPERVISE DATA INPUTS. 4) FAILED TO RECOGNIZE THREAT AND ERROR. GOOD -- KNEW SOMETHING REMISS. BAD: DIDN'T ACT ON IT UNTIL 1/2 WAY THROUGH FLT. NOTHING LEFT TO DO. TKOF WAS NORMAL. DIDN'T SEEM EXCESSIVE TKOF ROLL; FOR A HOT DAY -- HVY WT. I'VE BEEN FLYING FOR A LONG TIME NOW AND FROM TIME TO TIME; I RE-LEARN SOME LESSON I LEARNED IN THE VERY BEGINNING -- 1) SLOW DOWN; SMOOTH IS FAST. 2) DON'T LET ATC FLY YOUR ACFT. 3) IT'S OK TO BE LATE; BETTER THAN DEAD. I'M TRULY EMBARRASSED AND DISAPPOINTED WITH LACK OF SITUATIONAL AWARENESS. BUT I DO KNOW THIS ONE WON'T HAPPEN AGAIN.