Flights at Cologne airport were grounded on Monday after a man slipped through security unchecked, a police spokeswoman said.
Police at the Cologne Bonn Airport in western Germany later apprehended the man, whose evasion of security officials caused travel chaos.
All passengers waiting at Terminal 1 had to go through security checks again and flights due to depart from that terminal were grounded.
Five planes already on the runway set for take-off were forced to turn back to the terminal and their passengers were sent back into the airport building.
The spokeswoman said that officials were questioning the man, but were unable to give details on who he was and why he had skipped security.
She said it was too early to confirm a report by regional public broadcaster WDR that he had simply been in a hurry to catch his flight.
Airport passengers are now allowed to re-enter the terminal - but not before queueing up once again to go through security.
An airport spokesman said operations were not yet fully running as normal, but stressed that Terminal 2 was unaffected and that incoming flights were landing as usual.
In early March, a woman sidestepped security checks at the airport, prompting the evacuation of 1,000 people from Terminal 2 and an extensive search for explosives.
The 27-year-old later turned out to be a policewoman in civilian clothing.