BYO Sippy Cup
While some flights may provide baby equipment like sippy cups on board for younger passengers, you can’t always rely on flight attendants to have them readily available, or there may be other young kids on the plane who get to them first.
To avoid the risk of your kid spilling juice or other sticky liquids on themselves, you, or the plane, keep a sippy cup in your carry-on for easy access. You can always ask the flight attendants to fill them up for you as well.