Do you usually purchase a seat for a child under 2? While I know it's safer, it's such a hard call because of cost. We have previously flown twice with a child as a "lap child." We're thinking of going on a trip this spring (one, direct flight) and our airfare will be about $300pp. I thought we'd do "lap baby" again but of course then I get all worried and want to do the "safest" thing and buy a ticket. But, it's $300 more ($1500 as opposed to $1200). It almost makes me just not want to go at all and just postpone until next year when I don't have to make the call.
We have a free place to stay but still, man, now that we have to buy four or five tickets, and now that we have to rent a car b/c we can't just fit with DH's parents, this trip really adds up. We're looking at almost $2,000 just for air and rental. Ugh! And I used to debate about buying a $300 ticket for myself to go somewhere! I should have traveled more when it was easy.

Re: NWMR: Family air travel and lap kids
https://www.youtube.com/watch?v=ONRUpvbM2yc
and yes, runway emergencies, severe turbulence and emergency landings are much more common than you think. A car seat isn't going to save your child from a 30,000 feet nose dive, but it will save your child in many survivable emergencies that you would not be able to hold on to your child.
The child only needs to be in the seat when the seatbelt sign is on (taxi, take off, landing, turbulence etc), when it is off you can hold them etc. Everything in the plane is strapped down during these times, why wouldn't your baby be?
If it was safe for people to fly unsecured, they wouldn't have seat belts on a plane at all.
http://balletandbabies.blogspot.com
I've flew with DD 4 times before her first birthday. The longest flights were 6 hours direct and another that was a 5 hour layover sandwiched between a 5 and 7 hour flight.
Buying her an extra seat would have meant $700 and $1100 more for her.
It was cramped. But we managed. Once we did get an extra seat because the flight wasn't full. Southwest was great about letting us know that there was an open seat for DD AND let me bring her carseat on...even when the plane was fairly full.
I've never experience turbulence to bad that DD would have been in danger outside of a carseat. I've never skidded off a runway though I agree with PP that in a collision there is no way a human would be able to hold on to a child under that force of impact. And in a catastrophic crash a car seat isn't going to make a bit of difference.
We have two more flights scheduled before DD turns 2 and do not plan on buying her a separate seat.
I don't really get the flying vs driving study, I wouldn't pack all my kids and drive from NY-CA to save a couple hundred dollars (or even $1,000), on the other hand there is no way I would fly from NY to DC, I would just drive. Maybe there are people out there that would fly places that are less than 10 hours away, to me it sounds like a waste of money- it's sad that "enough" children have to die before they make it mandatory to buy a seat. One child should be enough.