The US Army parachute riggers course is about two months. Civilian ‘master’ and ‘senior’ rigging courses are 15-20 days each, but they are covering fewer types of parachute system. (The Army course covers not only personnel static line and freefall systems but also Type V pallet air drop configurations which utilize multiple configurations with drogue chutes and mains with stage reefing.) Those recreational riggers are also packing 30–60 parachutes a day, so they have a lot of experience by the time they have even a year on the job. Of all of the accidents that occur in recreational skydiving, the vast majority are the jumpers fault, either in not maintaining their gear, modifying critical hardware, or just doing stupid shit beyond their experience level.
I’ve worked with a few people who have gone through Army Airborne (jump) school, and a few who actually got their ‘black hats’ (instructor). They universally said that they would not jump with standard recreational skydiver outfits because of the lack of discipline and maintenance. I did an accelerated freefall program (8 freefall jumps) but didn’t go ahead with my Class A license, not because I had any serious problems but because the ride up in a Twin Otter asshole to elbow with 19 of my new ‘best friends’—some reeking of pot and pachouli—was far more nerve-wracking than the jump, and also I saw several injuries not in flight but at the landing zone where people came in trying to do crazy stunts and flew into someone already on ground or tangled canopies. I did one final jump out of a C-123 which was much better but also cost a lot more and still ended up in a scrum.
While it is possible to ‘weld’ some kinds of plastics with the right solvent and bonding agent, it doesn’t work too well with polypropylene (the most common material for plastic buckles), and will not develop the original strength of the injection molded part. Cyanoacrylate (‘Super Glue’ and similar adhesives) do not bond particularly well to polypropylene and only form an interface bond, plus they tend to break down the substrate which results in both a weak bond and a compromised base material. You can buy these buckles in packs of 10 or 20 (or in mixed sizes) about a buck apiece which makes it cheaper than fucking around with glue. This also allows you to keep multiple spares (because “two is one and one is none”) in a fix-it or boo-boo kit along with a thick sewing needle and thread (or dental floss works fine in a pinch) to make a quick fix in the field.
There is literally no reason to bother trying to glue a buckle back together because it is assured to break again, likely when it is least convenient and the only thing more annoying than breaking one once is having it break again because you were too cheap or lazy to fix it correctly.
You can buy a new buckle. And some grommets. The grommet setting tool is pretty cheap and is handy to have around. If you have a soldering iron that is also good. Choose grommets that will allow two, side by side. If you have a soldering iron. Loop the strap through your new buckle. Melt the appropriate diameter hole through the two layers of strap. Insert and set the grommet. Then do the one next to it.
There are also very nice threaded style rivets. Check out leather working supply sites. If the rivet head seems so small that it might slip through the hole. Install a wider washer.
I fix our various backpacks and other items with these methods.
An uglier but quick solution is actual nuts, bolts and washers. Trim off the excess bolt end.
Using a soldering iron to make the holes is best. It melts the edges so they do not fray and separate. Leading to loosening of the grommet, rivet, bolt…
It literally requires a dollar or two to buy a new buckle, and maybe US$10 to pay a tailor to stitch it into place if you don’t want to do it by hand. There is no need for “grommets”, or “melting the appropriate diameter hole through the two layers of strap“, or “threaded style rivets”, or “actual nuts, bolts and washers” to replace a broken buckle and restitch the strap unless you are cosplaying a Victorian-era steampunk hero.
Over the years I’ve worked my way through a 100 yard roll of 550 paracord, yet I’ve never parachuted. Meanwhile, by little brother spent years in the military jumping out of planes and didn’t know what paracord was when I showed it to him.
I don’t think it looks that bad when I do it. I do not especially know what I am doing so I use a simple backstitch. I just used polyamide sewing thread, though; never thought about dental floss. I suppose floss could be made of nylon, silk, etc.—they are not all the same.