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 "Pellston Regional Airport"): Pellston Regional Airport (IATA: PLN, ICAO: KPLN, FAA LID: PLN) , also known as Pellston Regional Airport of Emmet County, is a public airport located one mile (2 km) northwest of the central business district of Pellston, a village in Emmet County, Michigan, United States.
Relevant evidence: No