Just take reasonable care not to abuse the headwings. If you're carrying on, you'll be in control of it, and it shouldn't be a problem.
There's little loops of black on the back of the seat. One near each hip, two in the center near the top (I think level with the tether strap), and one on the side at about the same height. One backpack strap came with your seat. You attach the backpack straps to those little black loops. I highly recommend two straps, especially if you'll be wearing baby as well.
I recently traveled by myself with DD. Until I got the bags checked, I had DD (2yo, 24 pounds), Ergo with backpack accessory, Radian XT, and two rolling suitcases. DD chose to walk and "help" push the suitcases. Once we got through security, I put DD on my front, Radian on my back, and walked with two free hands. I put the Ergo on first, and leaned the Radian up against a wall or something. Put DD in the Ergo. Then stand up and put the Radian on. It was heavy. The Radian is 20-some pounds, plus DD, plus a full diaper bag. Probably close to 50 pounds, but at least it was balanced. I did have bruises on my shoulders after, but it was better than trying to hand-carry a carseat or have DD walk through the whole airport. It was also great to have hands free when I stopped on the layover to get food - no running-off kid to worry about, and two hands to deal with money and the food.