What is your suggestion?
As you already obtain and use METAR for airports my idea is to improve conditions / parameters when de-icing is requested.Generally instead of using temperature only make it depend on humidity as well. Let’s say temp is below 0 or equal and difference between air temp. and dewpoint is:
0-2 degrees, precipitation, vis < 5000m - high de-icing probability
3-4 degrees, vis < 5000 - medium prob.
5 and higher, good vis - no de-icing despite low temp.
How would it work in the game?
As described above
Why is this a good idea?
Less unnecessary and unrealistic de-icings.