Flight crew experiences reduced power takeoff due incorrect temperature setting in thrust management...

Attributes
ACN	114535
Time
Date	198906
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ccr
State Reference	CA
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	Medium Large Transport
Flight Phase	climbout : takeoff ground : preflight
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 160 flight time total : 7400 flight time type : 1500
ASRS Report	114535
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence other other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

Airfield temperature in centigrade was set on the thrust management system control unit for the computation of takeoff power. The data was obtained from the outside air temperature indicator and was about 8 degree higher than ambient. The temperature probe probably heated by sun while the aircraft sat on ramp all morning. The tms therefore set takeoff power that was less than maximum for the ambient conditions. I can preclude setting erroneous temperature in the future by always converting the ATIS temperature to centigrade and asking for a current temperature when the rate of change seems significant. It would benefit some if ATIS temperature were degree centigrade and fahrenheit.

Original NASA ASRS Text

Title: FLT CREW EXPERIENCES REDUCED POWER TKOF DUE INCORRECT TEMPERATURE SETTING IN THRUST MANAGEMENT SYSTEM CONTROL UNIT.

Narrative: AIRFIELD TEMP IN CENTIGRADE WAS SET ON THE THRUST MGMNT SYSTEM CONTROL UNIT FOR THE COMPUTATION OF TKOF POWER. THE DATA WAS OBTAINED FROM THE OUTSIDE AIR TEMP INDICATOR AND WAS ABOUT 8 DEG HIGHER THAN AMBIENT. THE TEMP PROBE PROBABLY HEATED BY SUN WHILE THE ACFT SAT ON RAMP ALL MORNING. THE TMS THEREFORE SET TKOF POWER THAT WAS LESS THAN MAX FOR THE AMBIENT CONDITIONS. I CAN PRECLUDE SETTING ERRONEOUS TEMP IN THE FUTURE BY ALWAYS CONVERTING THE ATIS TEMP TO CENTIGRADE AND ASKING FOR A CURRENT TEMP WHEN THE RATE OF CHANGE SEEMS SIGNIFICANT. IT WOULD BENEFIT SOME IF ATIS TEMP WERE DEG CENTIGRADE AND FAHRENHEIT.

Data retrieved from NASA's ASRS site as of August 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.

Flight crew experiences reduced power takeoff due incorrect temperature setting in thrust management system control unit.