Frankfurt Airport operator Fraport made a surprisingly strong return to profit in the first quarter despite worker strikes, it said on Tuesday. A €16 million ($17.3 million) profit from the traditionally weaker travel season followed a loss of almost €22 million a year earlier. Strikes at German carrier Lufthansa and at airport passenger security checks in the first quarter had risked affecting results, while dozens of flights were also cancelled due to snow and ice. But Fraport increased its revenue by around 16% in the quarter, mainly thanks to significantly higher passenger numbers at the g…