What safety seats cannot be used on an airplane?

What safety seats cannot be used on an airplane?

Stephanie Tombrello (Child Passenger Safety Educator & Executive Director, SafetyBeltSafe USA) gives expert video advice on: Is it safe to hold my baby in my arms while flying on an airplane?; Can my child use his car safety seat in an airplane?; Where is the safest place to seat my child on an airplane? and more...

Styles of seats that cannot be used on an airplane are booster seats and travel vests. The reason for that is that on most airplanes, except for some private jets, there are no shoulder lap belts and booster seats can only be used with a shoulder lap belt. The reason for this is that when you raise somebody up and you don't hold back the upper body the child's head goes farther forward than if you're lower on the seat. So if you only going to be held back at the hips you wanna be flat on the vehicle seat, not raised up. Travel vests are not designed, on the hold, to be used just for the lap belt and that's the reason they can't be used. When tests were done it was shown that the child moved, not only forward but begin to submarine under the system because it wasn't a rigid shell to contain the seat on the airplane seat.