In the middle of TNG : Lessons, the crew of the Enterprise-D is flying on a rescue mission toward Bersallis III, to save a Federation outpost from an impending fire-storm.

Upon reaching Bersallis III’s system, the ship drops out of warp. During senior officers meeting Riker states that it will take another hour to reach Bersallis III, so LaForge's team will have another two hours for a rescue transportation. When Riker tells this, we can clearly see, through windows behind him, that the ship is indeed travelling on conventional engines.

Why? Wouldn't it be more efficient in terms of rescue mission, to fly in warp until reaching the planet and not to waste another hour of precious time travelling?

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    Speculation: The Bersallis system is particularly cluttered, so trying to navigate it at warp would be tricky. The better solution is to drop out of warp at the edge of the system and go the rest of the way on impulse.
    – Roger
    Commented Jan 23, 2015 at 14:20
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    Out of Universe? It's required for the plot I think. In Universe? The same as why the transporters never could be used when it would be an to easy solution. Perhaps the fire-storm has impacts on the warp field.
    – Hothie
    Commented Jan 23, 2015 at 14:21
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    I can't find the proper source to cite at the moment, but I know for a fact that large gravity wells, like those created by planets and stars, interfere with warp drive. While they can still use warp engines even within those wells, it becomes increasingly difficult. Couple with the fact that Warp Speed Limit is in effect by this point in the series, and there may be an additional law about using warp near inhabited planets.
    – Zibbobz
    Commented Jan 23, 2015 at 14:53
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    @Zibbobz I think that is exactly the answer: "Don't warp within a solar-system!" Though this law has been broken many times for plot-convenience, I think it's still canon. Why not put it in an answer?
    – Einer
    Commented Jan 23, 2015 at 17:38
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    OP, I highly recommend you accept Richard's answer. It contains better citation than mine, including direct quotes from two episodes. I'd remove mine to encourage you to choose Richard's, but I don't want to remove the currently-accepted answer without warning.
    – Zibbobz
    Commented Jan 23, 2015 at 20:45

2 Answers 2


In short, warping inside a solar system is generally considered a last-ditch maneuver. It's certainly possible (and does occur in a number of episodes) but at the very least it seems to be highly inadvisable, presumably due to the large number of potential hazards such as interstellar objects and strong gravitational fields:

DAX : We're too far.

KIRA : Wanna bet? Take us to warp.

DAX : (concerned) Inside a solar system?

KIRA : If we don't, there won't be a solar system left.

DS9 : By Inferno's Light


TUCKER: You're going to warp?

PAXTON: A five second burst.

T'POL: (incredulous) Inside the system?

Enterprise : Demons

And even when the fate of the human race is at stake, the Enterprise doesn't risk an in-system warp jump:

WESLEY : Enterprise approaching the Terran system, sir...

RIKER : Slow to impulse... time to intercept [the Borg]...

WESLEY : Twenty-three minutes, fourteen seconds, sir.

TNG : Best of Both World, Part II

Although it's clear that the Enterprise will be cutting it fine getting to Bersallis III, it's evidently not worth risking a thousand lives trying to warp across the system merely to shave some time off of their estimated arrival.

  • A few hours*​​​ Commented Jan 23, 2015 at 21:33
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    @LightnessRacesinOrbit - I was using, whatchamacallit, hyperbole. To illustrate my point.
    – Valorum
    Commented Jan 23, 2015 at 21:45
  • Hyperbole involves exaggeration, but exchanging "a few hours" for "a few minutes" is the opposite :P Commented Jan 23, 2015 at 23:16
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    @LightnessRacesinOrbit - I think what you're driving at is litotes (humourous or rhetorical under-exaggeration) but in this case it's actually hyperbole since I'm exaggerating how small the benefit is.
    – Valorum
    Commented Jan 23, 2015 at 23:29
  • Hah, touché. Okay Commented Jan 23, 2015 at 23:49

Large objects like Planets and Stars can interfere with Warp travel, and in addition, sustained warp drive causes damage to subspace, as well as space as a whole as detailed in Force of Nature.

"Until we can find a way to counteract the warp field effect, the Council feels our best course is to slow the damage as much as possible. Therefore, areas of space found susceptible to warp fields will be restricted to essential travel only, and effective immediately, all Federation vessels will be limited to a speed of – Warp 5? – except in cases of extreme emergency."

That's Picard reading out Federation mandates that restrict warp travel.

However, the episode you are asking about takes place before the restrictions are put in place, so this alone can't explain the reason behind their premature drop out of warp.

However, if Starfleet is willing to impose safety limitations like this for the dangers of prolonged warp field usage, they're likely to use similar restrictions where warp failure would be catastrophic - for example, near an inhabited planet.

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    Downvoted because Starfleet were only aware of subspace damage in 7X09 whereas this episode is in season 6.
    – Valorum
    Commented Jan 23, 2015 at 18:40
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    @Richard My last paragraph addresses this discrepency - The assumption here is that there could be a safety protocol in place other than the warp field damage regulation. I'll try to make that more clear.
    – Zibbobz
    Commented Jan 23, 2015 at 19:26

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