There indeed seem to be a lot of folks commenting who think being able to safely have a car seat on a plane would be a revolutionary change, when that's the part that's a solved problem.

Pretty much the same experience I've had on other carriers. Where you can/can't put them is pretty logical.

The installation mode for planes is actually easier due to the standardization of the actual seat belts versus for cars the carriers will have different instructions depending on whether UAS is present, belt install, top tether, etc. In an aircraft there's really only one way to do it which is passing the belt through.

Certified rigid car seats are already allowed onboard and pretty much every airline you've ever flown on has clear guidelines on which seats they can be placed in for exactly that reason.

What do you think people are attaching the already approved rigid car seats to the aircraft with?

The argument, quoted by the GP, is about improperly restrained seats. They are only talking about those.

The GP also seems to think that having rigid car seats on plane would be a net new thing. They are already allowed and flight crew already check that it has the right certification and is attached correctly - this is much easier on a plane because the only way to attach them is the seat belt versus most seats have at least 3 different ways to attach in a car.

In this context the baby that isn't strapped in is the loose object. The use of car seats and harnesses is not just about a full loss of control of the aircraft and resulting crash.

In my experience they always stopped by to check that the seat was certified and that you knew how to install it. For aircraft install though it's usually simpler than a car because the only way to do it is a belt pass through.

Thing is a rigid car seat is what you ARE allowed.

My experience has been that as long as your car seat has the right certification they are allowed and the flight staff do check both that it has the certification sticker and that you've installed then correctly. The installation mode for planes is typically significantly simpler than in a car because it's just the belt pass through and seat angle. There's nowhere to attach a top tether.

Also, car seats are actually allowed as long as they have the right certification sticker.

This to me is the craziest part. Soft cloth baby carrier use is banned because of a 1994 study that tested car seats -- meanwhile I am allowed to put my baby in their car seat in the plane for the full duration of the flight including takeoff and landing.