Frankfurt Airport will be closed to departing passengers on Thursday due to a strike by security staff, a spokesman for the operator Fraport said on Wednesday. The operator recommends that passengers contact their airlines and said they should not travel to the airport under any circumstances. The impact on the flight schedule remained initially unclear. So far, planes are still expected to land and passengers on incoming flights are expected to be able to change at Frankfurt. Trade union verdi has called on ground staff at Germany’s national carrier Lufthansa to strike from Wednesday evening …