For domestic flights, you'll need a current and valid ID. If you don't have an ID, you can travel with a valid passport for both departure and return flights. Accident reports, birth certificates, and driver's licenses are not accepted.  

Unlike many airlines, Andes Airlines allows you to travel with your pet. However, you cannot travel with it on the plane. The pet must be transported in the cargo hold inside its kennel. You can purchase the service for any flight and must request it from official Andes Airlines contacts at least 48 hours before your flight.

Well, in most places you check in both online and at the airport and you'll have to print your boarding pass, but with Andes Airlines you can check in the normal way but instead of printing, you can present your boarding pass from your website and check in seamlessly at the information desk.