I'm going to have to disagree with you on the foot loosening issue. It is much easier for the child to accomplish this when the latch plate is at an angle to the webbing, as happened to me. It is probably close to impossible for a child to do this if it's not on a poor angle. If you see an install where it is on that angle, in my non-tech opinion, you should not be letting people drive away with an install like that, or you should at least be warning them.
That tilt-lock should be super hard to loosen, according to SKJP it should take two hands and a bunch of body weight, but when it's on an angle, it's not. My child wasn't exerting any great force on the adjustor, he wasn't angry and kicking and screaming, he was just sort of resting his foot/toe there because it's a natural ledge, and over the course of a car ride, that would loosen it. I checked for movement at the belt path, and it was always acceptably tight that way until he started resting his foot there.
I have to wonder how my install would have held up in a rollover or side impact crash if that minor amount of pressure was all it took to loosen the LATCH.
So I would say it's not clearly a behavioral issue like a child opening their chest clip. It is a design flaw, and parents should be made aware of it. I knew enough to check for tightness at the belt path, and I did so routinely for over a year before I started having problems. And it was very easy for my son to uninstall the seat with minor pressure from his foot, while I was driving. Checking before I started my drive was not enough to keep him safe. That should not be. The push button style adjustors are MUCH harder to loosen, and I am completely sure he would never have been able to get one of those open.
I certainly don't feel that you have to agree with me, but as a very experienced tech and instructor, I am able to tell when the latchplate is on an angle. Parents are given enough information at a seat check without being given information that isn't applicable to their situation and is likely to only cause unnecessary panic and doubt in the seat they have purchased for their child.
There is no benefit to the public in creating panic and doubt. In a collision the seat would first be moving away from the seat back in most cases. That movement would be a direction of pull that shouldn't cause a latchplate to slip if it wasn't on an angle to start with, so I'm not surprised that SK hasn't replicated the problem in their testing.
I've said it many times already, but lap belts can end up in the same situation. And some lap belts are very easy to loosen. In those instances - where you simply can't get the lap belt to stay locked, you have to choose another seating position in the vehicle as the seat is incompatible in that position.
This is different because it's the LATCH belt and that is going to move with the seat from one vehicle to the other. But the bare bone functioning part of the locking mechanism is identical to a lap belt. The seats that I have seen that have slipped while installed do not slip when you do a straight pull test, and that indicates a normally functioning locking latchplate. There is a higher rate of compatibility issues with it which is an issue, but parental education on checking for tightness and the experienced eye of a technician to recognize when the latchplate is on an angle are enough that I don't feel parents at check events should be told that some seats out there are able to easily loosen if a kid puts their foot on the adjuster. Some seatbelts can easily be unbuckled if the kid pushes their foot on the release button - that doesn't mean the vehicle has a defect. Granted it also doesn't automatically mean there isn't a defect.
It's unfortunate that this is affecting so many seat/vehicle combos - especially given that the radian is a seat with lots of room for the bigger rf'ing kids. The good thing is, that the kids who are big enough to be putting their feet down and pushing on it are probably also nearing the age of understanding to not do it.
I have asked some questions regarding lap only belts to try and determine if there is a minimum pressure requirement on the latchplate that needs to be required before it can lengthen. From what I have been told - to the best of this person's knowledge, there is no minimum pressure requirement on lap only belts for when the latchplate is on an angle. Given that the slippage is related to the angle the latchplate is sitting at, that's really the only area that I can see any potential for NHTSA to actually force a recall. If it's staying locked when not on an angle, then it's functioning normally.
I'm not trying to minimize your own experience, have watched it since you first posted on it so am quite aware of the things you've encountered with them, and quite frankly, I think that you've had horrible customer service from sunshine kids. But there is a balance when it comes to how much information a parent is given - they can only absorb so much in the short period of time you're dealing with them, and creating undue panic or worry is something I try to avoid. If it's not on an angle to slip, then it's a non-issue. If it is, then the seatbelt gets used. And I would be doing that anyways even without the online complaints regarding the slippage. If one method of installation won't hold a seat tight, you use the other or try a different seating position.
If there are some out there that are slipping when pulled on in a straight direction, then those are the ones to report to NHTSA. The ones that loosen as a result of twisting and tugging just to see if you're able to make it loosen only muddy the waters for the people who are in charge of investigating complaints. If there are true slippages out there that aren't happening because of the latchplate angle or a child's foot, then they're the ones that need to be focused on. To this point though, I'm not aware of any that have slipped when pulled on straight.
This doesn't mean that NHTSA won't find anything - none of us are privy to the exact investigations and procedures that go on behind closed doors and maybe they'll find an issue that the public isn't aware of for all we know. But the latchplate issue - when related to angle, isn't something I'm going to be talking about with parents. There are more important things they need to remember than something that isn't relevant or applicable to their own situation. If they're taught the basics and are checking for movement every trip, then they'll catch slight slippage before it is an issue in the event they change vehicles - and potential for future problems in some random vehicle also falls in to the category of something that shouldn't be addressed with a parent right off the bat.
Just my honest 2 cents. I don't expect you to agree, and I understand that you're frustrated and angry both with having had your seat loosen and the fear that comes with that, as well as the treatment that you've received from SK. Those are valid complaints. You and other parents really haven't received good customer service over this. But that doesn't mean that every parent needs to have fear put in to them, or that seatbelt installs should be needlessly used when they're often a lot harder for a parent to replicate. :twocents: