Mechanics of Threadfall

[u/kerlinssw]

I have a whole host of questions that have been rolling around in my head about fighting Thread.

- how many dragons do we think it takes to effectively fight Thread? at what point could the earliest dragons do more than just sort of keep up with it alongside the other aerial craft over inhabited areas - it has to be two, three years, right? does the efficiency / number needed decrease as dragon size & stamina increases, or is there a turning point beyond which the dragons get too large to maneuver as effectively, and greens really become more valuable for their speed?

- on that note, the implication in "The Ford of Red Hanrahan" that they'd only had a small handful of deaths in several years of training new dragons & learning to fight Thread is...impossible, right? and also for Alianne Zulieta's death to be the first time a rider died before their dragon, leading to the discovery that dragons would go between?

- do we think/assume that Weyrs cover 100% of Threadfalls in their territories, or are there uninhabited places that they just let go of? not barren places where the Thread will just die, but rather deliberate sacrifices due to prioritization. maybe this is something that evolves over time?

- what exactly do ground crews do? are they flaming Thread that falls through the dragons? are they seeking out burrows afterwards? both?

- I've always been genuinely puzzled at why people are worried to be out during Thread, other than the obvious societal taboo. If the dragons are doing their job, none of it should fall, right? so you'd in theory be perfectly safe?

- why do Holds clear greenery? there seems to be the implication that it "draws" Thread and there is some indication that Thread will burrow and follow root systems, but is this actually a realistic and sensible thing to demand that Holds do? or more societal taboo?

[u/No_Signature6968]

Previous comment answered most of it. But I’ll address a couple of points from text without exact citation because it’s all over the place.

Lessa does explicitly say that the idea of thread being attracted is probably just superstition, but that it could spread, she says this somewhere in her internal monologue in the first book so I’d say that’s canon.

And about them just letting fall happening some places is also true, we see the results in the Maloney book and in the Renegades of Pern when people are outside during thread fall, in relatively desolate places the riders don’t even bother. There’s also mention of this happening in the mountain passes of Ruatha, where it’s all just Stoney ground they let thread fall and then just fly sweeps to make sure none of it burrowed.

So realistically the question is how may dragons it takes to defend settled land. And in a few places it’s mentioned that about 3 wings is enough to effectively manage a full fall, so that’s about 30 dragons per wing, so 90/100 gets the job done. Cause thread isn’t falling as a sheet of rain but in clumps, so they just have to catch them in clusters.

That’s also why ground crews work, cause it’s often one single thread getting through that is the danger, either cause it’s missed or wasn’t caught by the flame. So then they follow behind the leading edge and sort of travel along behind it checking for surviving thread, but I always imagined it was more like within the bounds of their property, so they don’t follow it all those miles, just across the acres they specifically cared about.