Question: Which airport is located on an island, Wilmington International Airport or Ketchikan International Airport?
Context: Northern California TRACON (NCT) (Terminal Radar Approach Control), or NorCal TRACON for short, is an air traffic control facility that provides safety alerts, separation, and sequencing of air traffic arriving, departing, and transiting the airspace and airports in Northern California.  Located in Rancho Cordova near Sacramento, NCT controls airspace over 19000 square miles, and serves Reno International Airport, Sacramento International Airport, San Jose International Airport, Oakland International Airport, and San Francisco International Airport, plus 19 other smaller airports with air traffic control towers.  NCT is the 3rd busiest TRACON in America.  NorCal TRACON is the step between local control (in an airport's control tower) and Air Route Traffic Control Center (ARTCC), in this case, Oakland Center (ICAO code: ZOA).  San Francisco International Airport is the 2nd largest airport in California and the largest airport serving Northern California. The Gravina Island Highway is a 3.2 mi gravel highway located on Gravina Island, in the Ketchikan Gateway Borough of the U.S. state of Alaska.  The highway was part of a project that would connect Gravina Island, specifically, the Ketchikan International Airport, to the city of Ketchikan.  The Gravina Island Bridge, which would have connected the highway to Ketchikan was cancelled, but the highway was built.  Because the highway does not pass by or connect to any village or other place of importance, it has been nicknamed the "Highway to Nowhere". Grantley Adams International Airport (GAIA) (IATA: BGI, ICAO: TBPB) is the international airport of Barbados, located in Seawell, Christ Church.  It is the only designated port of entry for persons arriving and departing by air in Barbados and operates as a major gateway to the Eastern Caribbean.  The airport has direct service to destinations in the United States, Canada, Central America and Europe and serves as the second hub for LIAT.  In 2016, the airport was the 8th busiest airport in the Caribbean region; and the third busiest airport in the Lesser Antilles; after Queen Beatrix International Airport located in Aruba, and Pointe-à-Pitre International Airport located in the Republic of France within the island of Guadeloupe.  GAIA, also remains an important air-link for cruise ship passengers departing and arriving at the Port of Bridgetown, and a base of operations for the Regional Security System (RSS), and the Regional (Caribbean) Police Training Centre. Ketchikan International Airport (IATA: KTN, ICAO: PAKT, FAA LID: KTN) is a state-owned, public-use airport located one nautical mile (2 km) west of the central business district of Ketchikan, a city in Ketchikan Gateway Borough in the U.S. state of Alaska which has no direct road access to the outside world nor to the airport.  The airport is located on Gravina Island, just west of Ketchikan on the other side of the Tongass Narrows.  Passengers must take a seven-minute ferry ride across the water to get to the airport from the town. Ketchikan Harbor Seaplane Base (IATA: WFB, FAA LID: 5KE) is a privately owned, public use seaplane base located at the harbor of Ketchikan, a city in the Ketchikan Gateway Borough of the U.S. state of Alaska.  It is located near the Ketchikan International Airport, which also has its own seaplane landing area.  Prior to the opening of the Ketchikan International Airport in 1973, scheduled passenger seaplane service was operated with amphibian aircraft between the seaplane base and the Annette Island Airport located approximately 20 miles south as this land plane airfield previously served as the primary airport for Ketchikan with scheduled airline flights being operated by Pan American World Airways, Pacific Northern Airlines and Western Airlines into Annette Island over the years. Wilmington International Airport (IATA: ILM, ICAO: KILM, FAA LID: ILM) is a public airport located just north of Wilmington, North Carolina, in unincorporated Wrightsboro, Cape Fear Township, New Hanover County. Taquan Air is the operating name for Venture Travel, LLC, an American regional airline headquartered in Ketchikan, a city in the southeastern portion of the U.S. state of Alaska.  It operates domestic scheduled passenger and charter services.  Its base is Ketchikan Harbor Seaplane Base, which shares the same harbor and airspace as Ketchikan International Airport.  As per the United States Department of Transportation in a report dated August 2, 2010, Taquan Air is a "U.S. Certificated Air Carrier", and is 1 of 125 such carriers in the US. Piarco International Airport (IATA: POS, ICAO: TTPP) , and frequently shortened to Piarco International, Piarco Airport, or simply Piarco; is an international airport serving the island of Trinidad and is one of two international airports in Trinidad and Tobago.  The airport is located 30 km east of Downtown Port of Spain, located in the adjacent town of Piarco.  It is the seventh busiest airport in the Caribbean in terms of passengers served and third busiest in the English-speaking Caribbean, after Sangster International Airport and Lynden Pindling International Airport.  The airport is also the primary hub and operating base for the country's national airline, as well as the Caribbean's largest airline, Caribbean Airlines. Mae Fah Luang - Chiang Rai International Airport (Thai: ท่าอากาศยานแม่ฟ้าหลวง เชียงราย ) (old name: Chiang Rai International Airport (Thai: ท่าอากาศยานเชียงราย)) (IATA: CEI, ICAO: VTCT) is located in the city of Chiang Rai in northern Thailand.  The airport is about 8 km from the city center.  Since 1998 it has been managed by the Airports of Thailand Public Company Limited (AOT).  In 2013 the airport handled over 1,000,000 passengers and 7,000 passenger flights.  The airport has international flight facilities and serves 3 international routes to Hong Kong International Airport , Kunming Changshui International Airport and Haikou Meilan International airport.  In 2014, Airports of Thailand said that they would expand Chiang Rai airport.The plans include to build an additional taxiway, more shops and maybe extend the runaway.This should be completed in 2030. The Gravina Island Bridge, commonly referred to as the "Bridge to Nowhere", was a proposed bridge to replace the ferry that currently connects the town of Ketchikan, Alaska, United States, with Gravina Island, an island that contains the Ketchikan International Airport as well as 50 residents.  The bridge was projected to cost $398 million.  Members of the Alaskan congressional delegation, particularly Representative Don Young and Senator Ted Stevens, were the bridge's biggest advocates in Congress, and helped push for federal funding.  The project encountered fierce opposition outside Alaska as a symbol of pork barrel spending and is labeled as one of the more prominent "bridges to nowhere".  As a result, Congress removed the federal earmark for the bridge in 2005.
Answer: Ketchikan International Airport