TKOF ABORTED TWICE IN A ROW AFTER TKOF THRUST WAS MISCALCULATED BY FO. RPTRS CITE PUB DEFICIENCY DESIGN THAT CAUSED THEM TO MISCALCULATE REQUIRED TKOF THRUST.

Narrative

TSTMS AND LLWS ADVISORY ON ATIS CALLED FOR US TO USE A RATED THRUST TKOF INSTEAD OF A NORMAL (REDUCED THRUST) TKOF. I INCORRECTLY COMPUTED THE THRUST INDEX (A MEASURE OF PWR) USING DEGS FAHRENHEIT INSTEAD OF DEGS CELSIUS AS I SHOULD HAVE. THE INCORRECT SETTING CAUSED US TO DO 2 ABORTED TKOFS BECAUSE OF INDICATIONS OF INSUFFICIENT PWR. THE PROB WAS DISCOVERED WHEN MAINT DID A RUN-UP OF THE ENG; WHICH OF COURSE CHKED OUT FINE. I BELIEVE THERE ARE 2 THINGS WHICH MAY PREVENT THIS SORT OF INCIDENT. THE FIRST IS TO TRAIN NEW PLTS TO COMPUTE THRUST INDEX USING DEGS CELSIUS INSTEAD OF FAHRENHEIT. WHEN I COMPLETED TRAINING THE METAR/TAF (METEOROLOGICAL CODES/TERMINAL AREA FORECAST) FORMAT WAS INTRODUCED BY THE FAA BTWN TRAINING AND IOE. THE SECOND SOLUTION WOULD BE TO ELIMINATE REFS TO FAHRENHEIT ON OUR CHARTS SINCE ALL RPTS ARE NOW IN DEGS CELSIUS ANYWAY. SUPPLEMENTAL INFO FROM ACN 346300: WE DID NOT HAVE THE PROPER INDICATIONS SO I ABORTED. I ASKED THE FO TO RECHK HIS NUMBERS AND HE DID. HE STATED THEY WERE CORRECT. WE ATTEMPTED ANOTHER TKOF WHICH WAS ALSO UNSUCCESSFUL AND RETURNED TO THE GATE. AFTER MAINT TOOK THE ACFT THE ERROR WAS CAUGHT AND CORRECTED. WE DEPARTED TO OUR DEST 1 HR LATE. OUR COMPANY THRUST INDEX CHARTS HAVE FAHRENHEIT ON THE L SIDE OF THE CHART AND CELSIUS ON THE FAR R SIDE OF THE CHART. THESE CHARTS HAVE NOT BEEN CHANGED SINCE METAR AND TAF CAME INTO EFFECT. I HAVE RECOMMENDED THE COMPANY CHANGE THE CHARTS BY REVERSING THE TEMPS OR DO AWAY WITH FAHRENHEIT ALTOGETHER. OTHER FACTORS INVOLVED. A SHORT TURN IN BOISE. A 120 HR IN TYPE FO. MASSIVE TSTMS OFF THE DEP END OF THE RWY AND IN OUR DEP CORRIDOR. A 2000 ACRE FIRE 5 MI FROM THE ARPT THAT WAS LIMITING VISIBILITY. WITH EVERYTHING THAT WAS GOING ON I BELIEVE THE FO REVERTED BACK TO HIS INITIAL TRAINING AND USED THE FAHRENHEIT SCALE WHICH GAVE US THE WRONG THRUST SETTINGS. THIS WAS HIS FIRST ABORT ON LINE AND BEING PUMPED FROM THAT HE REPEATED HIS MISTAKE A SECOND TIME.