PARIS—Ryanair has applied for slots to base nine aircraft at Berlin’s Tegel Airport from summer 2018, in a challenge to EasyJet’s expansion plans there and in the broader German market following Air Berlin’s collapse. Dublin-based Ryanair, which also has nine aircraft based at Berlin Schonefeld Airport, previously criticized the way Air Berlin assets are being divided—with Lufthansa set to take over the bulk of those assets if it gets the green light from ...