Why and How do I tell her?

I have a good friend of mine that just got a convertible for her DD and I was checking it out the other day and I noticed she had the LATCH AND the seatbelt on it. Now, she is a good friend BUT she's kind of one of those 'dont tell me what to do' kind of people so I figure if I'm going to say anything about this I have 1 shot and I need to know all the facts.

I know its wrong to do both, but I don't entirely know why...

Anyone have some verbiage for me?

Thanks

Because the manual says not to..

It can be like having two outfielders go for the ball.

"I've got it!"

"I've got it!"

Ball ends up on the ground and you have two outfielders with black eyes.

Each system is expecting to take the full crash forces and stretch. The worst case scenario is that because neither gets the full crash forces neither stretches. Therefore all of the crash forces to into the baby, rather than into the protective straps and shell of the seat.

Wendy

:yeahthat: Thats a good explanation for you!! I was just going to say that using them both can cause them both to fail in the event of a crash but hers sounds much better

Is she someone who would be willing to check on the information on her own - if you give her a heads-up? If so, you could say something like, "I thought I read that you are only supposed to use LATCH or the seatbelt, but I'm not sure why." Then give her the link to car-seat.org and suggest she ask here to find out.

Melanie

"wow it's cool your seat allows you to use both the seat belt and LATCH at the same time, the manual on mine says I can only use one or the other"

Ah thanks Ladies, I think I'll approach it kind of like you said with a question like "oh your seat allows you to use both? All 3 of our car seats say not to use both because <insert Wendy's awesome explanation here>" and maybe she'll at least look at her manual or google it and see NOT to.

appreciate the help as always!

Another option would be to invite her to attend a seat check with you so she could have a CPST show her a safer way to install the seat.

In theory, even if neither system provides any stretch, you'd have even better coupling to the vehicle as the frame crushes in a crash. You'd minimize head excursion and possibly not do too much worse on other injury measures. My opinion is that most of the basis for not using both systems is that it would be prohibitively expensive to test and certify to federal standards (assuming you could even do this). Certainly, there are some scenarios where using two systems could be a safety issue, and we never know when this is the case, but I suspect that moving forward we may start to see at least some manufacturers revisit this guidance.

Ultimately, the best advice you can give to someone regarding a situation like this is to check their owner's manual and/or call the manufacturer.

A lot of this speculation would be avoided if only manufacturers, regulators and other agencies would realize the problem with imposing arbitrary LATCH limits. They are nearly impossible for parents find in many cases. Then, telling parents they have to discontinue LATCH or top-tether use at some weight only causes them to question if one system is inadequate by itself.