I said I was new here and I asked for advice. If you think its unsafe, then say that. If you have seen firsthand specifically how it is unsafe, then please tell me. Solid information would be more helpful than suggesting I'm an uncaring mother.
This is my current philosophy, which may change with more information/experience:
If it were life threatening to allow an infant on an aircraft without a seat, then it would be a law (like in cars) that ALL children be in a seat on an aircraft and children under a certain hight/weight would be required to be in an approved restraint.
I would never take my child in the car without her carseat. It is dramatically more likely for her to become injured in a car accident than on an airplane. She also gets injured on the playground, in the bathtub, at the pool- in fact: she has been injured by her carseat on more than one occaision. (she knows how to unbuckle it) Not serious injury, but I think I make my point. You have to asses risk with everything, and kids can get hurt.
If the plane crashes, well, we're all dead anyway. The carseat will be for take off/landing and when she falls asleep. All in all, roughly 5-7 hours of our 10hr flight. Even if I purchase the ticket and use the carseat I wouldn't keep her strapped in it for 10 hours. I'll have to take her to the potty and she'll want to walk around and see all the new things.
That being said, I am an inexperienced air traveler (probably a dozen or so trips in my lifetime). I have experienced turbulence. I have never experienced what I would consider severe turbulence, enough to bounce me out of my seat if I didn't have a seatbelt.