Hostile Action Displacement System

The HADS (Hostile Action Displacement System) was one of the defence mechanisms of a TARDIS. When the outer shell of the vessel came under attack, the unit dematerialised the TARDIS and rematerialised it a short distance away after the attacker had gone, in a safer locale. (TV: The Krotons)


 * The novelization of The Krotons indicates that the HADS had to be manually set, and the Doctor often forgot to do so, explaining why the TARDIS often didn't react to attacks.

The HADS of Drax's TARDIS could apparently be manually triggered when the vessel came under fire, but the account detailing this is probably apocryphal. (Search for the Doctor)

While stuck on Earth and attempting to avoid meeting himself, the Fifth Doctor engaged the HADS to move the TARDIS. (AUDIO: The Mutant Phase)

According to one account, the Rani was able to capture the Doctor's TARDIS in a tractor beam because the Sixth Doctor had neglected to set the HADS. (PROSE: Time and the Rani)

The HADS activated itself when two Zygons tried to steal the TARDIS. (PROSE: The Bodysnatchers)

After a particulary violent crash landing, the TARDIS used the HADS to move itself through time as well as space, appearing several days later. (PROSE: Dead of Winter)