The aircraft dispatcher is considered to be an additional crew member. The only difference is they don't sit in the cockpit put instead behind a computer screen sitting at a desk. The dispatcher's job is to work with the captain of that flight and plan all the routing, fuel planing, provide forecast weather, & load manifest. Once the captain & dispatcher agree that a flight can be made safely, then it is release. The captain finalize that release by signing a dispatch release certifying that they agree to the terms of the release, flight planning, fuel, and are healthy to fly. Even after the flight is release the dispatcher is continuously checking up on the flight looking for any potential problems such as severe thunderstorms along the route. The dispatcher could plan ahead by checking for conflicts with weather & call the captain to change the route mid-flight to create a better and smooth flight path for the passengers. The dispatcher is a valuable crew member behind the scenes.