Lionheart Protocol
From Tardis Wiki, the free Doctor Who reference
The Lionheart Protocol was a UNIT protocol which dictated that, in the event of a senior member going missing for more than three hours, any artefact connected to their abduction should be used to lure out the guilty party.
When Kate Stewart was abducted by the Eleven in 2014 or 2015, Petronella Osgood and Josh Carter triggered the protocol and the Arch was put onto an aeroplane to be moved from Edinburgh to London. The Eleven got aboard the plane and was arrested by hidden soldiers, although he attempted to escape and was pulled off of the plane by Adam Merchant. (AUDIO: The Enemy Beyond)
