If the illuminating plane is not a stealth plane, then it'll get shot by the stealth plane long before it can detect the stealth plane.
If the illuminating plane is a stealth plane, then you've just traded on stealth plane for another. Even worse, there's a decent chance that your broadcasting plane gets shot down, the illumination fails, and the enemy stealth plane still gets away leaving you one plane less for no gains at all.
If the illuminating plane is a stealth plane, then you've just traded on stealth plane for another. Even worse, there's a decent chance that your broadcasting plane gets shot down, the illumination fails, and the enemy stealth plane still gets away leaving you one plane less for no gains at all.