Tranzitions 3-in-1 Harness Booster (Model 2217738)

I like the ride safer vest for short trips. My kid starts to complain about it after about 30 min or so, though. We have this for longer trips: https://www.gracobaby.com/shop/car-seats/harness-booster-car-seats/tranzitions-3-in-1-harness-booster/SAP_2217738.html She's almost 6, about 45 inches and not quite 40 pounds, and we still have a fair amount more that we could loosen the harness.

We went from infant seat to extend to fit to Graco transitions to a cheap booster. But that's mostly because there was a sibling to use the next seat. Transitions can also be a backless booster. They didn't make rotating seats when my oldest was little so I never tried one.

The Graco Tranzitions is pretty lightweight, and it’s a 3-in-1 FF 5pt/HBB/no-back booster, so after the trip you could save it for later when he moves to a booster seat. Since it transitions to a no-back booster, you can take the back off to make it much shorter — so if you end up not having him sit on it on the flight, you could probably fit it into a carry-on bag for the plane, then put it back together at your destination. 

Pretty easy. I’d say <2 min each to take it apart and put back together. The manual has you take the harness straps all the way out when taking it apart since they’re assuming you’re about to use it in booster mode, but I don’t think you’d have to 100% uninstall them just to take the pieces apart. I can take a look at it tomorrow and measure how compact it can get when apart.

Agree nuna rava is super easy BUT It’s $$$ and def not a grandma spare type car seat. Diono radian is front facing 5pt harness and I find it easy to install, have it in my husbands car and often have to take it out when we are driving other adults. Chico kid fit high back booster very easy to install. Just attach to latches and pull tight at the front. FWIW I bought a Graco transitions as an extra for grandparents and anytime they take it out and reinstall themselves it’s insanely loose and not right at all. It takes a lot of effort on my part to get it tight enough.

2021 rav 4 2 forward and 1 rear facing Left is graco slim fit 3 in 1 with latch Middle is graco transitions with seat belt Right is graco infant car seat with latch. A lot of trunk space This setup also works with my 2019 Mazda cx5 but trunk space is way less than rav

i’m 5yr into the carseat game. the UB mesa was awesome/easy and we’re on our second graco (slimfit and now the big kid one). it’s under $200 and very safe. kept my kid RF until after age 5!

We have the Graco transitions and are using it on the plane. Lightweight and that way we have a car seat when we get to our destination