temperature

[Guest]

Hello,is there anybody able to explain the different type of mesuring the outside temperature?Why the temperature shown on the eicas is about at -5/ -15; we know that the outside temperature at fl 350 is about -50c, thus what is this temperature shown there?Thank you.Gauthier.

[michal 44]

The temperature you are referring to is TAT (total air tmperature) and it includes the warming part due to air friction at high speed (temperature on the surface of the wings). This temperature is important to pilots since it relates to potential freezing of the fuel.Your Progress page on the FMC shows correctly the true (SAT) Static air temperature - your "normal" air temperature.Michael J.

[Guest]

Thank you.How is the SAT calculated?Gauthier.

[Guest]

....and then there is the fuel temp on the overhead.Timothy

[michal 44]

Yes, and this temperature seems to me unusually high (comparing with TAT). However having no experince flying jets I can't tell if this is right or wrong.Michael J.

[Guest Ian_Riddell]

SAT, on the 767 at least, is calculated by the Air Data Computers using a combination of Mach and TAT. Mach, by the way, is calculated by the ADC's using a combination of calibrated and temperature compensated pitot-static data.Don't worry, I don't understand what I said either ;-)Cheers.Ian.

[Guest Ian_Riddell]

"Yes, and this temperature seems to me unusually high (comparing with TAT). However having no experince flying jets I can't tell if this is right or wrong."Don't worry about your flying experience, Michael, we wouldn't know either .... at least not without knowing your fuel distribution, what your aircraft was doing (in 3 dimensional space), what it was doing before, how long it had been doing it and where on the earth it had being doing it* :-lolCheers.Ian.* and.... what type of fuel you were using, what was the specific gravity of the fuel at the time of takeoff, what time of the day was it and was the sun shining on the fuel panel at the time.... the (real) fuel panel is notoriously difficult to read at times. It's an LCD display, the little windows in the control panel are always fogging up and it's positioned in an awkward spot on the overhead panel.

[Guest]

What Ian, you thought Boeing was going to make it easy or something?.....then we get into pounds vs gallons, vs liters, vs Imp Gallons.Its only awkward if you are wearing a tight tie, expensive starched uniform shirt, shoulder harness that locks up on its own accord, bi-focals, Ray Bans, hot humid environment cooling rapidly, headset chord tangled in arm rest and the lights dim....other than that....Timothy