Question: Mehmet Nazif Günal is 100% owner of a cargo airline headquartered where?

Context paragraphs:
North Star Air: North Star Air is a Canadian charter and cargo airline headquartered in Thunder Bay, Ontario, with secondary passenger hub in Sioux Lookout, Ontario, and cargo hubs located in Pickle Lake, and Red Lake, Ontario.  The majority of destinations served are remote First Nations communities, with regular service to 18 airports under "Flex Flight Passenger Service", and other regional destination under an on-demand basis.  Founded in 1997 as a floatplane operator with two DHC-2 Beaver aircraft based in Pickle Lake, ON, the airline has grown over the years and came under new ownership in 2012.  In 2015 Cargo North and North Star Air merged under the North Star banner.

Mehmet Nazif Günal: Mehmet Nazif Günal (born 1948) is a Turkish billionaire property developer, the chairman and 100% owner of MNG Holding, and MNG Airlines.

ULS Airlines Cargo: ULS Airlines Cargo, formerly "Kuzu Airlines Cargo", is a Turkish cargo airline headquartered in Istanbul with its main base is Istanbul Atatürk Airport.  It operates international freight services.

Azal Avia Cargo: Azal Avia Cargo (Cargo Airline of the State Concern Azerbaijan Hava) is a cargo airline based in Baku, Azerbaijan.  It operates scheduled and charter cargo services within Azerbaijan and to other CIS countries.  Its main base is Heydar Aliev International Airport, Baku.

LATAM Cargo Brasil: LATAM Cargo Brasil, formerly "TAM Cargo" and previously "ABSA Cargo Airline", is a cargo airline based in Campinas, Brazil.  It operates scheduled services within Latin America and between Brazil and the United States, as well as charter services.  Its main base is Viracopos International Airport.

Aloha Air Cargo: Aloha Air Cargo is an American cargo airline headquartered in Honolulu, Hawaii, operating from a hub at Honolulu International Airport.  Formerly part of Aloha Airlines, it became an independent cargo operator following the closure of the passenger airline in 2008.

SkyLink Express: SkyLink Express is a cargo airline headquartered in Mississauga, Ontario, Canada.  It operates dedicated air cargo/courier feeder flights throughout Canada and USA and provides on demand air cargo charters from its bases in Vancouver, Winnipeg, Hamilton and Montréal-Mirabel.

Gemini Air Cargo: Gemini Air Cargo was an American ACMI (Aircraft, Crew, Maintenance, & Insurance) cargo airline headquartered in Dulles, Virginia, USA.  It operated worldwide cargo schedules and charters on a wet-lease basis.

MNG Airlines: MNG Airlines is a Turkish cargo airline headquartered in Istanbul with bases at Atatürk International Airport and Cologne Bonn Airport.

Martinair: Martinair, legally "Martinair Holland N.V.", is a Dutch cargo airline headquartered and based at Amsterdam Airport Schiphol and a subsidiary of Air France-KLM.  The airline was founded in 1958 by Martin Schröder.  Since 2011, Martinair has operated entirely as a cargo airline with scheduled services to 20 destinations worldwide and additional charter flights.  Prior to that date, passenger flights were also operated.

Supporting paragraphs: Mehmet Nazif Günal MNG Airlines
Answer: Istanbul