Just open any .gsc that has a onplayerspawned thread in it. (_rank.gsc is commonly used)
and add this under onplayerspawned:
Every time someone spawns, they will get an emergency airdrop.
self maps\mp\killstreaks\_killstreaks::giveKillstreak( "airdrop_mega", false );
If you want to give more than one, just add wait 0.1; and paste the line again, as many times as you want. (altho one each spawn seems sufficient)