Parts of Frankfurt Airport were evacuated on Tuesday and dozens of flights cancelled after a French family of four got past security despite a positive test for explosives.
Police blamed “an error by a security officer”.
It led to boarding being halted and a partial evacuation of Terminal 1.
The family were later found, questioned and allowed to travel on. A police spokeswoman said one of them had not fully completed security checks.
Police did not clarify what had triggered the positive explosives test.
A similar incident on 28 July at Munich Airport caused 300 flights to be cancelled, affecting 30,000 people.
BBC