I asked long time about that and Crazy Ivan said: it's not possible.
BTW every object in game can be in EMCON status - even if haven't EMCON option to check.
All you have to do is open scenario in txt editor and add EMCON 1 string under "prob" or lower
...or you can wait for RA 1.48 - this feature will be added to all objects in game (land objects, airctafrs etc)
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