The HADS can be found on all Type 38 and later TARDISes. As a four dimensional entity, a TARDIS is able to detect (and sometimes respond to) exterior dangers before the danger manifests itself. If the HADS has been enabled, then the Relocation Device will automatically dematerialize a TARDIS if its Exo-Shell is threatened. Using the Time Safety Jump feature it will travel forward in time up to one hour to escape. It will then materialize in a, random spot within one mile of its previous location. The system's settings sometimes need to be adjusted as its can be over sensitive. It is not unknown for a hailstorm to trigger the HADS. The HADS have an emergency manual override control, which can even be used by someone without a symbiotic nuclei. As an alternative, the Defense Force Fields or Defense Indefinite Time-Loop Option can be slaved to the HADS to trigger instead.