Lufthansa's 18.6% increase, to 130 million passengers, was fuelled by its Jan-2017 acquisition of Brussels Airlines and strong growth by Eurowings (which benefited from airberlin's demise). Wizz Air was the fastest-growing among the top 20 groups, followed by a resurgent TAP Air Portugal.
Ryanair (whose growth is, by contrast with Lufthansa's, organic) would have kept the number one position – won for the first time in 2016 – if it had not trimmed its winter growth to address operational problems. Even then, the Irish LCC still grew at 10.3%, to 128.8 million passengers, and comfortably remained Europe's biggest individual airline.
In 2017 the Lufthansa Group has reclaimed from Ryanair the title of Europe's biggest airline group by passenger numbers.
Icelandair / Presidential Aircraft / Martinair / Tui Arkefly / easyJet
Ryanair Budget / Transavia / Rosiya Airline / Lot Poland / Wizz Air / Swoop Air /
Condor Airlines / Turkish Airlines / Btritish Helicopters / Brussels airline / CargoLogicAir / Imperial Airways / Transmeridian TAC Cargo / Air Inter / Monx / Air Caraïbes /
Dutch Kroonduif / Polet Airlines / Air Peace / TAROM
Tower: "Delta 351, you have traffic at 10 o'clock, 6 miles."
Delta 351: "Give us another hint! We have digital watches."