As flights over Greece surge to new highs, concerns are mounting over outdated air traffic control infrastructure, recent system failures and whether long-delayed upgrades can keep pace with soaring demand.

A fire broke out Wednesday afternoon in an outdoor area at Athens International Airport "Eleftherios Venizelos."

Under the concession deal, the Greek government is estimating 71.2 million euros in state revenues and 28.3 million euros in investments.