Takeoff aborted twice in a row after takeoff thrust was miscalculated by first officer. Rptrs cite p...

Attributes
ACN	346301
Time
Date	199608
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : boi
State Reference	ID
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	climbout : takeoff other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 120 flight time total : 2800 flight time type : 120
ASRS Report	346301
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : atp pilot : instrument
Experience	flight time last 90 days : 125 flight time total : 6100 flight time type : 1000
ASRS Report	346300
Events
Anomaly	non adherence : published procedure other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : rejected takeoff other
Consequence	Other
Supplementary
Primary Problem	Chart Or Publication
Air Traffic Incident	Pilot Deviation other
Situations
Publication	Unspecified

Narrative:

Thunderstorms and LLWS advisory on ATIS called for us to use a rated thrust takeoff instead of a normal (reduced thrust) takeoff. I incorrectly computed the thrust index (a measure of power) using degrees fahrenheit instead of degrees celsius as I should have. The incorrect setting caused us to do 2 aborted takeoffs because of indications of insufficient power. The problem was discovered when maintenance did a run-up of the engine, which of course checked out fine. I believe there are 2 things which may prevent this sort of incident. The first is to train new pilots to compute thrust index using degrees celsius instead of fahrenheit. When I completed training the metar/taf (meteorological codes/terminal area forecast) format was introduced by the FAA between training and IOE. The second solution would be to eliminate references to fahrenheit on our charts since all reports are now in degrees celsius anyway. Supplemental information from acn 346300: we did not have the proper indications so I aborted. I asked the first officer to rechk his numbers and he did. He stated they were correct. We attempted another takeoff which was also unsuccessful and returned to the gate. After maintenance took the aircraft the error was caught and corrected. We departed to our destination 1 hour late. Our company thrust index charts have fahrenheit on the left side of the chart and celsius on the far right 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 temperatures or do away with fahrenheit altogether. Other factors involved. A short turn in boise. A 120 hour in type first officer. Massive thunderstorms off the departure end of the runway and in our departure corridor. A 2000 acre fire 5 mi from the airport that was limiting visibility. With everything that was going on I believe the first officer 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.

Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Takeoff aborted twice in a row after takeoff thrust was miscalculated by first officer. Rptrs cite publication deficiency design that caused them to miscalculate required takeoff thrust.