Air Berlin chief executive officer Joachim Hunold tendered his resignation after 20 years in charge as Europe\'s third-biggest discount airline prepares to slash routes and ground planes in an effort to stem losses. Hunold, 61, plans to step down September 1 and recommended that board member Hartmut Mehdorn, 66, the former chairman of German state rail operator Deutsche Bahn, should become interim CEO. The stock traded 2.9 per cent lower in Frankfurt after jumping 4.4 per cent when the resignation was announced. Air Berlin will scrap unprofitable routes, cut frequencies and partially withdraw from regional airports to focus on four main hubs, the company said yesterday in a statement. European routes cut Article continues below More than half of the 1 million seats that are being eliminated will go at the City Shuttle division that serves European business centres. \"I\'d planned to step down for some time but thought it better to resign at this juncture so the company can make an unburdened fresh start,\" Hunold, who wants to remain a director, said on a conference call. Hunold, who had previously worked at charter carrier LTU, joined Air Berlin as managing director and majority shareholder in 1991. American founder Kim Lundgren had to seek local owners when German reunification gave the country sovereignty over Berlin\'s airspace for the first time since the Second World War. Air Berlin shares have declined 33 per cent this year, valuing the company at €213 million (Dh1.12 billion). Ryanair Holdings, Europe\'s biggest discount carrier, has slipped 17 per cent and EasyJet, the No. 2, is down 23 per cent.