Time track

A time track, also called a space-time track, (AUDIO: The Dalek Conquests) temporal track, artron trail, or time path, (PROSE: A Device of Death) was a path through time related to a time vessel or traveller. "Jumping" a time track could place a time traveller off their intended destination in time, and could even cross their own destiny.

According to the Fifth Doctor, time tracks were to time what parallel dimensions were to spacetime, running side by side like grooves on a record. Travel along the groove and time progressed or regressed in a linear fashion, but skipping a groove meant the distance travelled increased or decreased exponentially. (AUDIO: Aquitaine) Compassion considered the record analogy - and by extension the term "skipping a time track" - to be overly simplistic explanations. (PROSE: The Brakespeare Voyage)

According to Susan, a time traveller had to be careful when travelling through time lest they jump a time track and wind up in one of their unfulfilled potential futures, unable to properly synchronise with their intended destination. (AUDIO: Tick-Tock World)

When faced with instability, the Doctor's TARDIS could jump back on her temporal vector in order to reach a stable time track, somewhere she'd been before. In one case, the TARDIS brought the Fifth Doctor back to Telos, mere hours after the Second Doctor departed. (AUDIO: Secrets of Telos)

Physics

The Sixth Doctor explained that time tracks could diverge from the causal nexus of a large time fissure, allowing for travel to a parallel universe (AUDIO: The Wreck of the Titan) or an alternate timeline, (TV: The Space Museum, AUDIO: The Mutant Phase) although the Fifth Doctor stated that travel to a parallel universe was not possible as the time tracks didn't meet.

Crossing time tracks created recursions that had unpredictable effects. They behaved differently in different universes. (AUDIO: Renaissance of the Daleks) The First Doctor and Susan Foreman visited the fourth universe which didn't run exactly parallel to N-Space as its time tracks crossed at an angle. (AUDIO: Quinnis)

The distance between time tracks is non-linear, as the Fifth Doctor mentions when he is on the Aquitaine. It is subject to Delahay's inverse cube law, which means that although someone may have only been thrown backwards in time a few seconds, they will actually be about three hours behind. (AUDIO: Aquitaine)

TARDISes either possessed or created time tracks as they travelled. An Osiran lodestone picked up the residual vortex energy of the Doctor's TARDIS's time track, drawing it off course. (PROSE: The Sands of Time) While looking for a TARDIS to copy for the the Rani, Iam found the Sixth Doctor's space-time track and copied his TARDIS. (PROSE: State of Change)

Instances

Susan suspected that the echoes who inhabited the Tick-Tock World were time travellers who had jumped time tracks. An alternate version of Susan, having lived on the planet for a millennium, learned how to navigate the time tracks via her consciousness alone. (AUDIO: Tick-Tock World)

The First Doctor jumped a time track in the TARDIS. The TARDIS seemed to only partially materialise, turning the Doctor and his companions into ghost-like visitants in an alternative future timeline in which they had becomes exhibits in the Moroks' Space Museum on Xeros. (TV: The Space Museum)

In a transmission recovered and recorded in The Dalek Conquests, the Daleks located the Second Doctor's space-time track, positioning him in London, England on the planet Earth in the 20th century time zone, 20 July 1966. (AUDIO: The Dalek Conquests, TV: The Evil of the Daleks)

The Fifth Doctor's TARDIS jumped a time track and was thrown through a time corridor, ending up in an alternate timeline in which the Daleks mutated into insect-like monsters. (AUDIO: The Mutant Phase)

TARDISes possessed a time path indicator, which alerted travellers if something was following them along their same path. (PROSE: The Dark Path) Time track crossing protection protocols were pre-set circuits in TARDISes that were supposed to be engaged all the time. When visiting a place multiple times, this prevented a TARDIS from reaching it by making the TARDIS think it had just been somewhere when it really hadn't. The Doctor's TARDIS's protocol was sometimes engaged and sometimes not, which often caused it to jump time tracks. (AUDIO: Renaissance of the Daleks)

The Fifth Doctor believed someone was trying to communicate with him across the astral plane, possibly from his own time track. (PROSE: Goth Opera)

After breaking the Key to Time, (TV: The Armageddon Factor) the segments were scattered along the Doctor's time track. (COMIC: Time & Time Again)

The Seventh Doctor was trapped by the the Rani, and was jumping time tracks between the years 1973, 1993, and 2013. During this time, he jumped back and forth between his third, fifth, sixth and seventh incarnations, while Ace, his current present companion, became a number of his past companions. (TV: Dimensions in Time)

The Eight Doctor of an alternate timeline, so as not to cross his own time track, orchestrated Elizabeth Klein taking his TARDIS back to 1944 to negate her own timeline, repairing the damage to the Web of Time. (AUDIO: Klein's Story)

When the TARDIS once landed in between times, in a time where this was no time, the Eighth Doctor believed that he and his companions had jumped a time track. (AUDIO: Time Works)

The Ninth Doctor and Rose Tyler chased a Chula ambulance through the Time Vortex. It began jumping time tracks and the Doctor lost it for a while which caused it to jump ahead of the TARDIS. He managed to find where it landed and believed it to only have landed, at maximum, a month before he and Rose arrived. (TV: The Empty Child)

The Tenth Doctor jumped a time track in the TARDIS that allowed him to visit the era of the Second Dalek War before the Last Great Time War. (PROSE: Prisoner of the Daleks)

Mentions

On an Earth-like planet, the Doctor noted that the silence reminded him of Xeros, prompting Vicki to ask if they had jumped the time track again. (TV: Galaxy 4)

The Eleventh Doctor suspected that the TARDIS had slipped a time track when he, Amy and Rory were having several dreams, before discovering it was the work of psychic pollen which had fallen into the TARDIS's time rotor. (TV: Amy's Choice)