When my daughter was small we used to fly frequesntly from here to Denver. The thing that my doctor suggested and I found to have worked was to have something ready for them to suck on during departure. When the cabin pressure changes and your ears start to pop it helps to swallow. So, Im not sure if you breast feed or bottle but that is an option. Hold off to feed until departure or if your daughter will suck on a pacifier that is another option. That is mostly the worst part is when the cabin pressure changes. One time my daughter got motion sickness but she was well over a year by then. Encouraging the swallowing is what I found best.