I've flown with my infant sons over a score of times as lap babies, but it wasn't until a series of flights earlier this month on LAN that I'd seen and used an infant lap belt.

I think its pretty clear why most airlines don't use them: baby lap belts are a quick, effective way to help strangle your infant to death. If the baby is neither perfectly upright nor sitting with excellent posture on your lap when wearing this belt, then there's a percentage chance greater than zero of strangling your kid.

I used it once. After that, I covered my little guy up with a blanket while holding him and lied to the FA when she came by to confirm I was using the belt.