Both my daughters are frequent travellers and we have rarely had difficulties with this. But, when it has come up, anythingto suck on works. Bottle, finger, pacifier, sugar free lollipop (when they are alittle older) or pretty much anything.

Also, your child will know they need to suck so don't worry about not taking a bottle unless they are hungry. The sucking will relieve the pressure and they will recognize this.

best of luck.