sp - "the probe indicated the ice temperature"- thus you are saying that ice that forms at -39C will be at a significantly higher temperture?
BOAC, I think that the theory is that the probe is heated, but not enough to handle the conditions. As the ice forms (at the atmospheric temperature, plus a bit of latent heat from the state change), that ice is then heated by the heating element of the probe.... or something like that.
Can someone remind me how/where SAT is derived on a/c?
The Rosemount SAT/TAS probe.
(The lower sensor is the Rosemount probe housing - the other is an ozone detector, for the MOZAIC programme.)