Take a look at http://www.airliners.net/open.file/294127/L/ TAT of 51*C! :-eek Or am I mistaken? Sure Turkey is warm, but this hot? Can the residual heat of a flight be this effective?

Keep in mind that TAT usually runs ~20 degrees warmer than SAT. That would place your outside air temperature around 32C or so, which is not unreasonable.

Not when you're sitting still!Wade

Whoops! I didn't look at the picture the first time ;-) Heh.Anyway. 52C is hot, however if you've ever spent a summer in Phoenix, 45C (~113F) at 10pm has happened on more than one occasion. I've gone swimming in Phoenix at 1 am before while it was still around 40C (~100F). I imagine it could happen in Turkey too ;-)

Ian is going to have to help me out here, but isn't the TAT probe heated/cooled using bleed air?Maybe if there was no bleed air on the ground then the temperature could read higher than actual?

That has to be a mistake... The picture was dated October 29th, 2002... According to the Weather Channel, the average high on that day in Istanbul is 17C, or 63F. A temp even in the upper 20s (centigrade) would have been very unusual.http://www.weather.com/outlook/travel/clim...4?climoMonth=10Later,Neil

Hi Stratus_Fractus,The thing with TAT probes is that they are internally heated for deicing purposes and are not reliable on the ground. They need airflow through them to be accurate. Here is an excerpt from the 727 maint. manual and the 737 is basically the same."The total air temperature probe is provided with an internal heating element for deicing when in flight which is controlled by the left pitot static heater switch on the overhead panel (Ref Chapter 30.) NOTE: FedEx operations call for the pitot static heater switches to be turned ON after engine start. Depending on the length of time from engine start to the takeoff roll, the TAT indicator may show an OFF flag and/or an off scale indication. This condition is normal and is due to the TAT probe temperature exceeding the operational limits of the indicator. The indicator should return to normal during takeoff roll or shortly after takeoff."Hope this clears things up.Cheers,JohnBoeing 727/737 mechanic

Thanks for the replies, makes sense.

That's the sanest answer yet. Thanks for the info.

"Ian is going to have to help me out here, but isn't the TAT probe heated/cooled using bleed air?"Don't think I can explain this one, HP. I have seen high readings as a result of probe heat tests using maintenance test switches (on the 767, a Probe Heat test switch is located on the P61 panel at the 1st Obs position), but I was under the impression that the crew don't use these switches. However, if you do use them, it's important not to run them for longer than 30 seconds... and to allow 5 minutes for them to cool down before repeating the test.On some aircraft, direct sunlight on the nose of the aircraft also produces higher than normal temperature readings, but as you can see from the photograph, it's nighttime.The temp sensor is located deep inside the probe and will only work properly if air is flowing through the probe. Parked at the gate or at slow speeds, the airflow may be insufficient, so engine/apu bleed air is used to _suck_ air across the sensor (using a venturi effect). I'm sure you've heard that sucking sound on your walkarounds as you pass the left hand side of the nose. A few weeks ago, I was inspecting one of the TAT probes on a 747-400 and found the bleed air coming out of the probe to be cool. Perhaps by the time the hot bleed air has reached the nose (via metal tubing), it has cooled. It may be the same for the 767.(Electric) TAT Probe heat is only active in the air on a 767, so I don't think you'd see these sort of temperatures on a 767 on the ground. The 737-700 may have a completely different setup however.Curious.Cheers.Ian.

Another clue might be that the photographer mentions that two aircraft rushed by his aircraft.... Perhaps hot air from their engines was affecting the TAT readings?Cheers.Ian.