Question: Both the Appleton International Airport and the Pellston Regional Airport are categorized as what by the Federal Aviation Administration (FAA) National Plan of Integrated Airport Systems for 2017–2021?
Sentence (from "Bishop International Airport"): The airport is currently served by several passenger airlines: Allegiant Air, Southwest Airlines and Delta Air Lines operate mainline service out of the airport, as well as affiliates of Delta Connection, United Express and American Eagle.
Relevant evidence: No