Weapons invulnerability

[Tulkas]

Apparently it is not possible with general mission options to make planes invulnerable to weapons but still able to crash with mother earth or other planes, is that right?  

Is it possible to do through scrips?

Thanks

[razo+r]

Your first assumption is correct.

You can use a script called "Fox" (google DCS Fox script). It will destroy missiles before they hit you, but you are still vulnerable.