Cengiz Topel Airport — Kartepe, Turkey

Cengiz Topel Airport (KCO) is located in Kartepe within Kocaeli Province in northwestern Turkey, historically operated as a Turkish Naval Air Station alongside limited civilian service. Named after a Turkish naval aviator, the airport has periodically hosted scheduled domestic flights connecting the industrial Kocaeli region, near Izmit, to other Turkish cities, though civilian passenger operations have not always been continuous. Kocaeli itself is one of Turkey's major industrial centers, home to significant automotive and petrochemical manufacturing, meaning KCO's potential civilian role is tied closely to business travel demand in the region. Given its dual military-civilian status, KCO's availability for commercial flights has varied over time, and its role remains secondary to Istanbul's larger airports for most travelers heading to the broader Marmara region.