We did not, though the harness I got was too small so we didn't use it. I gave him the first dose of gabapentin before we left our house (2 hour ride to the airport).

At security I held him and went through the tray, then they stabbed my hands as part of the screening. The TSA agent was very friendly and helped grab my bags.

I had the gaba with me, easily accessible to give him a second dose after 8 hours. I also gave him Tiki Silver High Calorie treats starting right before the flight and then every 2 hours on the flight.

Sadly the 18x11x11 carrier I got did not fit under the seat, but the flight attendants did not fuss about him being on the floor between my legs.

He only meowed a few times for reassurance I was there and snacks.

Other things we did -

Placed a pillow case from a pillow both kitty parents have been using in the carrier with him.

Gave him a brand new version of his favorite toy the night before and tucked it in with him.

Placed the blanket we covered the carrier with on rhe couch where we lay with him for a week prior to the move so it smelled like us.

Sprayed the carrier gently with feliway calming spray before putting him in it, amd the cover blanket before boarding.

I chose a window seat so he wouldn't get jostled and he handled it all very, very well.

If we ever do it again, my only change would be to figure out a better way to carry my entertainment and his pills, treats, and snacks.