Estimated Time of Arrival (ETA)
Once a TARDIS has dematerialized and the Epsilon Coordinates are input the ETA will be displayed on the console. Since the Artron Mainframe usually calculates the Epsilon Coordinates, the Estimated Time of Arrival is based (in theory) on the space-time distance covered, and the efficiency of the Epsilon calculations. The TARDIS also uses data from the Mean Free Path Tracker to plot the ETA. A TARDIS travels forwards in time faster than backwards because it isn't fighting the flow of time and, in general, the larger the temporal jump the longer the flight. However because of difficulties in creating a safe path through the vortex physical distance has little affect on travel time. A trip of 1 mile often takes longer then crossing half the universe. While a TARDIS journey can take 9 weeks, in practice, it is rare for a trip to take longer then two days.
ETA also varies on the current state of agitation of the Vortex. Some operators claim the "mood" of the ship affects the ETA. This claim could have some basis in fact. Being four-dimensional beings TARDISes actually prefer travelling in the Vortex to inhabiting the Multiverse. However TARDISes have Curiosity Circuits. Without these circuits a TARDIS would never leave the Vortex. Despite all these variables, the displayed ETA will be accurate to within 5%. The materialization indicator will light up and begin to grow brighter and brighter during the last 60 seconds of a journey. It should be noted that the ETA display will not be updated if the TARDIS's course (and arrival time) is altered by some outside force. Regardless of a TARDIS' current position in the Vortex a flight to Gallifrey never takes more then 10-30 minutes. For example it takes 10 minutes to get to Gallifrey from 21st century Earth.
Using the Space Time Throttle it is possible for an Operator to control the effective "speed" of the TARDIS by altering the "length" of the route (and thus extend perceived travel time) through the Vortex. The Time Altimeter is used to monitor these changes in the "speed" of the TARDIS. When the total power is reduced a TARDIS's trips through the Vortex take longer.
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.