As of 6th of April 2019, Istanbul has a new airport in operation. It is called Istanbul Airport (In Turkish: Istanbul Havalimani) and is located some 35 km north of the city center on the Black Sea coast in the European side of Istanbul. The old main International airport - Istanbul Ataturk Airport has been shut down for commercial operations. The IATA designator “IST” formerly used by Ataturk airport is transferred to the new airport.
Amsterdam Schiphol Airport (Iata code: AMS) is the third busiest airport in Europe, serving over 70 million passengers a year. Schiphol airport is a hub for KLM airlines (Part of Air France - KLM group), their subsidiary Transavia and easyJet. Schiphol is important for connecting flights linking Europe and USA as the US Delta airlines links Amsterdam with 11 major destinations in USA.
Skopje International Airport (IATA code: SKP) serves the capital of the republic of North Macedonia (formerly FYROM) and is the only major International airport in the country. The other International airport is situated near the lake of Ohrid (IATA code: OHD) and serves only seasonal flights.
Since the republic of North Macedonia lacks a national carrier, the airport of Skopje is being used only by foreign carriers. It is linked with direct flights to most of ex-Yugoslavia capitals, namely Belgrade, Zagreb and Ljubljana. Qatar Airways, Fly Dubai, Turkish Airlines, LOT Polish Airlines, Austrian Airlines, Aegean and a few other carriers also operate to Skopje International Airport.
“Virtual interlining” is a relatively new term in the aviation vocabulary. It derives its meaning from the term “interlining”, which Wikipedia defines as: “Voluntary commercial agreement between individual airlines to handle passengers traveling on itineraries that require multiple flights on multiple airlines. Such agreements allow passengers to change from one flight on one airline to another flight on another airline without having to gather their bags or check-in again.”