Switzerland's aviation agency is revoking the commercial flight license of a local airline that operated vintage propeller planes after one of its aircraft crashed in the Alps last year, killing all 20 people on board.

The Federal Office of Civil Aviation said Tuesday that it reviewed the risks of passenger flights with vintage planes after Ju-Air's 79-year-old Junkers Ju-52 crashed in southeastern Switzerland on Aug. 4. It concluded that continuing commercial flights "no longer fulfills today's safety demands" and said rules elsewhere in Europe are also set to be tightened this year.

The office said that, while Ju-Air can no longer operate commercially, it will — provided it fulfills various conditions — be able to continue private flights for registered members who are aware of the heightened risks.