Analyzing air cargo flows of Turkish domestic routes: A comparative analysis of gravity models*

This study examines the domestic air cargo traffic within Turkey utilizing the basic gravity model and focuses on comparing the ordinary least squares (OLS) and Poisson pseudo-maximum likelihood (PPML) methods using Turkish domestic air cargo data based on city pairs between the years 2012 and 2020. This study also highlights that estimating the same coefficients for the explanatory variables causes bias when the departure and arrival cities have different effects on the dependent variable. The results reveal that variables such as GDP per capita, population, and distance have positive and statistically significant effects on the amount of air cargo carried. It is concluded that while the GDP per capita of the departure city has a greater impact on the amount of air cargo between the two cities compared to the GDP per capita of the arrival city; the population of the arrival city affects the amount of air cargo to a greater extent in comparison to the population of departure city.