There are many benefits to checking in early for your Alaska Airlines flight. Check in anytime from 1 to 24 hours before your flight. You can check in online on your computer or mobile device. If you have any questions, contact Alaska customer service at 800-252-7522 or 1-844-902-4930 (OTA Skip-Waiting). Alaska Airlines Check In allows you to select your preferred seat in advance. Pay your checked baggage charges online with a credit or debit card, then bring them to the baggage-check location. Check in early and relax before your flight takes off. For more information, visit Airlines Pet Policy.