are numerous families of FTL references in Star Trek, including a
number of closely related estimates. As seen in the series-specific
pages, each series has its own distinctive treatment of FTL drives.
In general, 23rd-24th century Starfleet ships can be expected to cruise at speeds around 1,000-10,000c, and to hurry at speeds of 100,000-1,000,000c. Milage may vary, however.
FTL speed citations may be divided into five major groups.
First, ambiguous references. These are, for a variety of context-specific reasons, compatible with most warp scales. These occur in every series.
Second, outliers. A handful of estimates are difficult to fit with any consistent warp scale.
Third, references to craft achieving FTL speeds while at impulse or another non-warp drive.
Fourth, the TOS warp paradigm, which has its firmest foundation in the Enterprise's travels to the edges of the galaxy and occasional thousand-light year sprints.
Fifth, the VOY warp paradigm, which is based on the idea that the fastest ship the Federation has to offer would take a lifetime to cross the galaxy.
The primary basis for comparing these is consistency across the series. Discarding the first three groups, we find that support is split fairly narrowly.
In favor of the TOS paradigm, we have all of TOS, ENT, about 80% of DS9, ~50% of TNG, and VOY. Standing for the VOY paradigm and against TOS, we have almost all of VOY, 20% of DS9, and 50% of TNG. Although TOS has broader support, the total number of examples across the entire franchise is fairly close.
While the Voyager warp paradigm is central to the story arc of Voyager, it has serious consistency issues even within Voyager, and the treatment of speeds in TOS is the singularly most consistent of any Trek series. The contradictions also tend to be more striking; Voyager is not simply outpaced by the Enterprise in its faster moments, but also by runabouts and primitive 22nd century vessels.
We may best mitigate the contradiction between the two systems by assuming that Federation ships have fuel economy issues at higher speeds.
On the low end, there exist a series of estimates made from TNG, DS9, and VOY regarding a return from a 70,000-75,000 light year trip across the galaxy into uncharted territory; these and a few other references place cruising speed at ~1000c.
For Federation vessels, we come upon the following set of speeds by reference:
There is one consistent element: With minor modifications by more advanced civilizations, truly insane speeds are readily achieved with an otherwise ordinary warp core and parts on hand.
References to travel to the other side of the Federation in TNG and DS9 are clarified by STVIII, in which the Federation is discerned as 8,000 light years across. Circumnavigation of the Federation in three months ("Valiant") can be suggested as being around a 100,000 sustained cruising speed by a vessel that has trouble reaching warp five. Cestus III being two months' off and two weeks by subspace suggests a range of 6,000-48,000c for a normal cargo ship. The "other end of the Federation" suggests a similar transit speed for Riker hitching his way along.
So we have a problem. In TOS, the galaxy is freely and easily travelled. STV gives us an Enterprise that can hop 50,000-60,000 light years' round trip before Kirk's vacation time runs out. Voyager, along with some supporting references in TNG and DS9, suggest it would take an entire human lifetime to travel a similar distance. On the flip side, it's easy to travel around the Federation, and most of the quadrant is open for business - easy to reach, easy to talk about. Actual speeds are all over the place.
The TOS paradigm is the one most consistently applied within a single series. It's compatible with most of TNG and almost all of DS9. DS9 by itself would give us faster short-haul, cruising, and slow-ship speeds than TOS, but suggests slower top speeds, long haul speeds, and very poor speed through unexplored territory (TOS gives us speeds through unexplored territory that are every bit as fast as speeds through charted territory.) TNG gives us one thing: Confusion. STV gives us an insane speed that we can't use. Voyager gives us speeds consistent with most of TNG, but inconsistent with TOS and most of DS9, and seems unbelievably close to a ship two centuries and 4.975 warp factors slower in ENT.
The fact of relativistic shielding on modern UFP ships - cited in STVIII - forces "Best of Both Worlds" (TNG) to be implicitly FTL impulse; it cannot be denied that impulse drives are capable of FTL speeds, albeit slow FTL speeds.