The TAT has warmed from -42°C to -38.8°C over a very short time. They must have just entered the warm rising air of a CB.
OK. But this is at odds with Cllandestino
Originally Posted by rudderrudderrat It's a clue that you've just entered a region of much warmer air suddenly.
No trace of it on FDR concurrent with the comments. Blockade of TAT probe did rise the apparent temperature 40 seconds after the comments were made
So did the outside temp really increase as the crew believed (and turned on anti-ice)? Or was this increase due to a blocked TAT probe?
OK. Assuming they are talking about increasing cockpit temp rather than outside, I guess the possibilities include:
1. Increased heat production within cockpit. Unlikely.
2. Increased transfer of heat into cockpit. Increased outside temp and lag in climate control adjusting for this would be one cause, but there are others..
3. Decreased transfer of heat out of cockpit.
4. Loss of (or decreased ) air flow around the pilots leading to decreased evaporative cooling. This would only cause an perception of increased temperature rather than a true increase in temperature.
Many of these explanations involve altered internal air flow. So what exactly is the "change in background noise" noted twice at 02.08.17 and 02:09:40. During this 83 second period, the PF questioned whether the PNF had adjusted the A/C, both pilots noted a smell of ozone, and both pilots noted increased cockpit temp.
I can accept increased TAT due to rising air from Cb, and this explains the ozone. However Clandestino states TAT did not rise during this period, and further that the FDR did not record a change in vertical acceleration.
If Clandestino is correct, there must be another explanation for the increased temperature. The changed background noise and the smell of ozone (or whatever) may be relevant to this explanation.