When the Locking Down Mechanism is activated, a TARDIS will seek out and lock on to the nearest habitable environment. This step will be omitted if the TARDIS is already materialized in such a location. Once locked on, Fail-safe prevents any dematerialization or materialization of a TARDIS until the switch is deactivated. Emergency doors will be generated in any areas of the TARDIS that (due to dimensional instabilities) have been cut off from the Main Doors in the Control Room. These doors will lead to the outside of a TARDIS and will appear integrated into the local environment. The existence of these doors will be unstable until the emergency bypass device is engaged.
Though it can be manually activated by the operator, the TARDIS will automatically initiate Fail-Safe if the TARDIS is about to break up (possibly due to a complete failure of the Main Space-Time Element while in the Vortex). Removing the Primary Refraction Tube from the Locking Down Mechanism prevents the Fail-safe setting from being changed.
The following color code is used:
- Black: For information from the TV Series, including Dimensions in Time, and 1996 TV Movie.
- Blue: For information from the Novels and Audios including Target, Virgin, BCC, and Big Finish.
- Green: For information from 'licensed' reference sources such as the Technical Manual, Doctor Who Magazine, and the Role Playing Games.
- Red: For information from unofficial sources -The Faction Paradox series, behind the scenes interviews, author's speculation, and popular fan belief.
The TARDIS Technical Index is copyright Will B Swift.