I wouldn't do the tylenol thing. It's not always the best idea. At 11 weeks she is still probably sleeping a bunch. And the flight probably wont disturb that too much at that age. Make sure you can either have a bottle or your breast
ready for landing as it can upset her little ears. Also try a pacifier if she takes one. Besides that, just plan on making some trips up and down the aisle walking her around. Bring a few little toys to entertain her. Flight attendants are usually able to get you some warm water if you need to make bottles. The one pain in the butt can be changing diapers. Most airplane bathrooms don't have changing tables. Change her right before you board the plane and if she isn't poopy, maybe you can last the flight without having to do that.
Good luck, and remember, most people on that plane, at one time or another, had a crying baby on a plane
It will probably be better than you think! It's when they get older it gets trickier!