These are a staple everywhere! I recommend Neutrogena's because they come in a fantastic, small travel size. These are great for:
Preparing for your sheet mask and cleaning off any residue from your sheet mask.
Wiping your fingers if you apply tinted moisturizer, or cleaning up any smeared makeup if you sleep on the flight.
Cleaning up any potential stains.
And keeping on the nightstand in case you have too much fun and feel tempted to sleep in your makeup!