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In determining safe viewing distance, seems to me there are discrete threats to consider:

First is the rocket blowing up on the pad, or just above it. That would have no warning. There would be a distance where you would be out of range for the fire, shockwave and flying debris.

Next is an out of control event where the rocket goes sideways and is detonated. This would give a little warning. Videos I have seen of this show the detonation in a few seconds. So I don't imagine it could get very far.

There might be a possibility of an out of control rocket that cannot be detonated for some reason. I don't know if that is ever considered, or if they presume it can always be detonated. I don't know if that has happened in modern times.

I expect they would not allow people in the downrange direction until they are past the first stage, 300 miles or so.

I imagine there would be a large grey area where there is a possibility, but extremely small one, of a hit by flung debris. I wonder if any launch sites allow people in those areas.

Does anyone know how launch facility people calculate safe distance and what they are? Besides Florida, other sites may have different policies.

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    $\begingroup$ "An out of control rocket that cannot be detonated for some reason" has indeed happened. In Feb 1996 a Long March went out of control and crashed into a nearby village. Official death toll was 6 but some consider that a drastic underestimate. en.wikipedia.org/wiki/Intelsat_708 $\endgroup$ Feb 4, 2018 at 17:41
  • $\begingroup$ Video of the incident showing the remains of the village youtube.com/watch?v=FBJ9ue6GKek $\endgroup$ Feb 4, 2018 at 17:46
  • $\begingroup$ Yes, I was aware of this accident. I just didn't know if the rocket was detonated intentionally. It could have been and still landed on a village. The video you posted does seem to show it breaking up. The article didn't mention how far the village was from the launch pad. $\endgroup$ Feb 5, 2018 at 0:17
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    $\begingroup$ @OrganicMarble: I know that "An out of control rocket that cannot be detonated for some reason" is trivially true for Proton, for the simple fact that the "some reason" is that the Proton doesn't have a Flight Termination System. Could the same be true for Long March? Is that detail publicly known or secret? $\endgroup$ Feb 5, 2018 at 21:45
  • $\begingroup$ @JohnnyRobinson: "An out of control rocket that cannot be detonated for some reason" is always true for the Russian Proton, since it doesn't even have a Flight Termination System. The Russian solution to the problem is simply to launch in the middle of nowhere, where there's nothing to hit. The results look like this: youtu.be/EJ5__1PPgNQ The US, OTOH launches pretty close to populated areas (at least "close" at rocket speeds). $\endgroup$ Feb 5, 2018 at 21:51

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All you ever wanted to know about the calculations: https://commons.erau.edu/cgi/viewcontent.cgi?article=1028&context=stm

For US launched Range Safety is redundant on rockets. We won't discuss the Chinese safety measures or the Russian N1 "accident" or the "nuclear" rocket explosion in August 2019 or ... (Etc.). All countries have their own version of "safe".

The document lists "the types of hazards associated with space launches":

Distance-Focusing Overpressure: The detonation of rocket propellants can produce a ‘blast overpressure’ shock wave that can damage structures and injure people.

Debris Impact Hazard: Falling vehicle components and payloads from failed launch attempts, or debris from their aerodynamic or commanded breakup, can damage aircraft in flight and structures on the ground as well as injure individuals. In addition, some debris may detonate on impact, producing a Blast Hazard, or may act as firebrands to initiate fires on impact.

Toxic Effluent Exposure: Toxic propellants as well as the chemical byproducts associated with the burning of propellants can injure people on the ground. This is chiefly associated with toxic liquid rocket propellants and gaseous plumes from solid rocket motors as they burn, explode or break up in flight.

(Ed note: See "BFRC" (Big Friggin Red Cloud) w.r.t Hypergolics)

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  • $\begingroup$ Is this the correct reference? It looks to be a very interesting document but its qualitative and has no calculations or narrative about quantitative topics. $\endgroup$
    – Puffin
    Feb 3 at 21:55

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