Flight delays stranded thousands of passengers across Brazil for a fourth straight day on Friday.
At least 77 flights were canceled and 200 of the 822 flights scheduled before noon Friday were delayed by at least an hour, according to Infraero, the nation's airport authority.
The delays have snowballed since earlier in the week due to technical problems and a slowdown by air controllers alleging malfunctioning equipment and poor working conditions.
Television stations showed long lines of tired, annoyed passengers at check-in counters in Rio de Janeiro and Sao Paulo. Some stretched out to sleep on the floor.
But there were no reports of violence or threats. Officials beefed up security Thursday at the Brasilia airport after angry passengers briefly seized check-in counters.
The Air Force, which oversees Brazil's air traffic control system blamed the delays on problems with radar screens and a communications link failure that occurred on Tuesday.
Russian Foreign Minister Sergei Lavrov said at a briefing in Beijing that the question about the shipment of S-300 anti-aircraft missile systems to Syria had not been resolved yet. However, Syrian Ambassador to Russia Riyad Haddad said that S-300 missile systems had been delivered to Syria last month