In the early days of the pandemic, when demand for air travel abruptly flatlined and international borders closed, "ghost flights" became a common phenomenon.
원문출처 : https://www.cnn.com/travel/article/ghost-flights-pandemic-greenpeace-cmd/index.html
원문출처 : https://www.cnn.com/travel/article/ghost-flights-pandemic-greenpeace-cmd/index.html