I agree, if we could add pelicans and phantoms, Invasion would be so much better, I mean think about it, when you get tier three, a pelican spawns and then you can pick up someone to go get the objective. And instead of bringing it to another pelican which would be useless since you're already in one, bring it to like a dawn in halo 3 or an autumn in halo 1 to escape with it sort of like in the ending of halo reach where you deliver cortana to the autumn. Also if pelicans are added, they shouldn't be indestructible because then invasion would be useless and the Spartans would always win (assuming the players aren't noobs).
That's what I think. Post to comment or add new ideas, because I want to know what you think.