As far as I know, a manpacked portable missile system has no sharp edges or points, so it should be able to be brought through security and loaded on to the aircraft.
I'm not sure if it will fit under the seat or in the overhead compartment.
p.s. I don't work for Airport Security.
I'll bet it is too long to fit in the little test bins. The gate attendants would spot them in a heartbeat and make them go back to the ticket counter and check it in with the rest of their bags.
You simply can't sneak ANYTHING past them.