Does this mean that PVC motor casings can be considered to be unsafe? My answer to this question is a straightforward no. PVC motor casings are not unsafe. Let’s do a simple thought experiment to justify this assertion. Suppose you fire a rocket motor with a PVC casing (or any material, such as steel, or let’s be silly for just a moment and include glass). If you stand 1 metre away and the motor CATOs, the likelihood of your getting injured is 100%. Now let’s say you stand 10 metres away and the motor CATOs. The chance of your getting hurt is, say, 50%. Now let’s say you stand 30 metres away and the motor CATOs. The chance of your getting hurt is small, maybe 5%. Now let’s say you stand 1000 metres away and the motor CATOs. The chance of your getting hurt is zero. Clearly then, the safety of a rocket motor is not dependant upon what material the casing (or other parts of it) are fabricated from, it’s distance that makes this determination. This is, of course, intuitive, but not everyone puts faith in intuition. A rational analysis such as this thought experiment clearly illustrates the fallacy of the claim.

How far away, therefore, should a person be situated when firing a rocket motor? There is no simple answer, other than, the farther away you are, the greater the degree of safety. Safety is a prime consideration in the field of rocket engineering, whether it be amateur or professional. Understanding, and being able to judge such matters is a prime necessity for any prospective amateur rocket engineer. Humans have an innate ability to assess risk (it is keyed into our genes, after all). Use this innate skill to judge the distance you feel is "safe". Let your video cameras sit in the danger zone and capture the sight and sounds in vivid, close-up detail, keeping yourself at a safe distance.

A rocket motor needs to be electrically ignited and that does place a practical limit on distance. Unless a wireless system is used, practical considerations regarding length of the Launch Controller cable come into play. My Launch Controller (a.k.a. Ignition System, detailed here) has a spooled wire of length 75 metres (250 ft.) in length. Based on my experience having fired hundreds of rocket motors of all types and sizes, this is a distance that I feel is safe for all smaller rocket motors (say, up to J-Class). For my larger-sized Muon (M-class) rocket motor, I added an extension of 25 metres for a total distance of 100 metres (330 ft.). My Launch Controller features light gauge speaker wire which, when bought by the spool, is inexpensive. Spools of speaker wire up to 500 feet (150 m.) are readily available.