Darwin Airline SA is a Swiss regional airline with its head office in Bioggio, Lugano flying under the brand name Adria Airways Switzerland.
 It has been operating scheduled domestic and international services throughout some western European countries using the brand name Etihad Regional from January 2014 until July 2017 when it was sold from Etihad Airways to Adria Airways as well as formerly also on behalf of Alitalia.
 Its bases are Geneva Airport and Lugano Airport.
Sandefjord Airport, Torp (Norwegian: "Sandefjord lufthavn, Torp" ; IATA: TRF, ICAO: ENTO , marketed as TORP Sandefjord lufthavn) is an international airport located 4 NM northeast of Sandefjord, Norway and 110 km south of Oslo.
 The airport features a 2989 m runway aligned 18/36.
 Torp partially serves as a regional airport for Vestfold and in part as a low-cost airport for Eastern Norway and the capital of Oslo.
 Widerøe have a base at Torp, serving both domestic and international destinations.
 It also sees scheduled flights by Norwegian Air Shuttle, Ryanair, Wizzair and KLM Cityhopper.
 The airport served 1,851,181 passengers in 2013.
Achmer Airport (German: "Flugplatz Achmer" ) (ICAO: EDXA) is a regional airport located 4 km southwest of Bramsche, a town in the district of Osnabrück in Lower Saxony, Germany.
 It supports general aviation with no commercial airline service scheduled.
Peninsula Airways, operating as PenAir, is a U.S. based regional airline headquartered in Anchorage, Alaska.
 It is Alaska's second largest commuter airline operating scheduled passenger and cargo service, as well as charter and medevac services throughout the state.
 It also operates scheduled passenger service in several regions of the continental U.S. Its main base is Ted Stevens Anchorage International Airport, with other hubs located at Portland International Airport in Oregon, Boston Logan International Airport in Massachusetts and Denver International Airport in Colorado.
 PenAir currently has a code sharing agreement in place with Alaska Airlines with its flights operated in the state of Alaska as well as all of its flights in the lower 48 states appearing in the Alaska Airlines system timetable.
Cimber Sterling A/S, also known as Cimber Air and styled as Cimber Sterling, was a Danish airline based in Sønderborg, Sønderborg Municipality, Denmark, operating scheduled domestic and international services in co-operation with Scandinavian Airlines (SAS) and Lufthansa.
 Its main bases were Copenhagen Airport and Billund Airport, with a smaller base at Aalborg Airport.
 The airline filed for bankruptcy on 3 May 2012.
Autolinee Regionali Luganesi (ARL) is a public transport operator in the region around the Swiss city of Lugano.
 It operates bus services from Lugano to various outer-suburban communities.
 There is some overlap in terms of places served with the Trasporti Pubblici Luganesi (TPL), the Lugano city bus operator, and Autopostale, the regional post bus operator.
PT Merpati Nusantara Airlines, operating as Merpati Nusantara Airlines, was an airline in Indonesia based in Central Jakarta, Jakarta.
 It was a major domestic airline operating scheduled services to more than 25 destinations in Indonesia, as well as scheduled international services to East Timor and Malaysia.
 Its main base was Soekarno-Hatta International Airport, Jakarta.
 The word "merpati" is Indonesian for "dove", and Nusantara is a Javanese word found in the "Pararaton" ("the Book of Kings", probably written in the 16th century) and meaning "the outer islands" and now referring to the Indonesian archipelago.
 Merpati is also listed in category 1 by Indonesian Civil Aviation Authority for airline safety quality and plans to get IATA Operational Safety Audit (IOSA) from International Air Transport Association.
 It had a maintenance facility based at Juanda International Airport, Surabaya as well as a simulator facility at the Merpati Training Centre in Surabaya which housed a Fokker F-27, AVIC MA60 and CN-235 full motion simulators.
Arkia, legally incorporated as "Arkia Israeli Airlines Ltd" (Hebrew: ארקיע‎ ‎ , "I will soar", Arabic: خطوط أركيا‎ ‎ ), is an Israeli airline.
 Its head office is on the grounds of Sde Dov Airport in Tel Aviv, Israel.
 It is Israel's second-largest airline, operating scheduled domestic and international services, as well as charter flights to destinations in Western Europe and across the Mediterranean.
 Its main base is Sde Dov Airport, with hubs at Eilat Airport and Ovda Airport.
Arad International Airport (IATA: ARW, ICAO: LRAR) is located 4 km west of Arad, in western Romania, in the historical region of Crișana.
 The airport is located only 60 km north of Timişoara Airport.
 Arad International Airport also has a cargo terminal, the largest and most modern in western Romania.
 It is located 250 km from Budapest and 300 km from Belgrad.
 It’s located near the border with Hungary, only 30 km from the closest point for crossing the border - Turnu and 20 km away from the closest railway point for crossing the border - Curtici.
 The airport also serves as the SMURD regional air ambulance base for the 5 western counties that form the region (Arad, Bihor, Timis, Hunedoara & Caras-Severin).
 SMURD Arad operates 1 Eurocopter EC135 converted for the air ambulance role.
 Arad Airport is directly connected to the A1 motorway (part of the Pan-European Corridor IV), one of the most important and heavily used motorways in Romania.
Lugano Airport (IATA: LUG, ICAO: LSZA) is a regional airport located 4 km west of the Swiss city of Lugano, approximately 80 km north of Milan, in the municipalities of Agno, Bioggio and Muzzano.
 It lies closer to the village of Agno than to Lugano itself, and is sometimes known as Lugano-Agno.
 Around 200,000 passengers use the airport each year, using some 2,400 flights.
 There are also limited freight operations, a flying club and flight school.
 The headquarters of Darwin Airline are located at the airport.

Question: Lugano Airport is a regional airport located 4 km west of the Swiss city of Lugano and headquarters of a Swiss regional airline that has been operating scheduled domestic and international services throughout some what?
Answer: western European countries