The bulk of remaining commercial flight offerings come from small regional commuter airlines such as Ravn Alaska, PenAir, and Frontier Flying Service. The smallest towns and villages must rely on scheduled or chartered bush flying services using general aviation aircraft such as the Cessna Caravan, the most popular aircraft in use in the state. Much of this service can be attributed to the Alaska bypass mail program which subsidizes bulk mail delivery to Alaskan rural communities. The program requires 70% of that subsidy to go to carriers who offer passenger service to the communities.