Is anti ice simulated where I will have problems and how will I tell. What temperature will I realise this is going to happen. With the colder weather coming I was hoping to see this.

 

Rob

On the Boeing 777, Anti-ice is automatically turned on when required unless a system has failed. It will show up as TAI on the ECIAS.

 

Ice formation requires 2 things. Water (Moisture) and Temperature.

 

Moisture comes in various forms including:
Water (rain)

Ice (Hail)
Snow

Clouds

Fog

Mist

Freezing Rain (supercooled pure water which is below 0 degrees but hasn't frozen because it hasn't had anything to 'cling' to and is instead liquid surrounded by surface tension).

 

When Ice gets very very cold, it becomes so solid that it cannot 'stick' to anything, and just bounces off like rocks. This is why ice at -55°C isn't much of a factor. (though if you have ice at -55°C you may be inside a thunderstorm CB at FL370, not the best idea, and turbulence and convection currents in the air may be of concern, along with actual structural damage from the solid ice hitting the aircraft radome/windscreens/wings etc).

 

So "it's cold" isn't enough to cause ice. Oxygen and Nitrogen won't turn to Ice (well it can, but not unless you're in space or some science lab).

 

I think FSX determines "Ice" from the Dewpoint and Temperature and cloud levels. if you are inside an altitude band where FSX has determined "cloud" to be, and the temperature is between about +8°C and -20°C (this is a guess) then the program turns on that little switch called "Ice is present". PMDG 777 responds to this by turning on the Anti-ice, which turns some messages on in the EICAS and results in a slight rise in the Idle thrust N1.