The last time the FAA took up this issue, in 1995, it found that "if forced to purchase an extra airline ticket, families might choose to drive, a statistically more dangerous way to travel."
The aviation agency noted that highways are much more dangerous with 43,000 highway deaths in 1994 compared to 13 on commercial flights. (While the numbers have changed a bit for 2009, there are still much fewer airplane fatalities: there were 33,963 U.S. traffic deaths last year compared to 45 on commercial flights.)
"Statistics show that families are safer traveling in the sky than on the road," the FAA said back in 1995. "We encourage the use of child safety seats in airplanes. However, if requiring extra airline tickets forces some families to drive, then we're inadvertently putting too many families at risk."
No airline wants to be the first to start charging extra for young children and possibly lose customers. Airlines contacted by ABC News said they would follow whatever rules the FAA imposed. None said they would be willing to voluntarily go beyond that.
For instance, JetBlue said: "We abide by FAA rules and will comply when and if they decide to make any changes." The airline, like most others, posts an extensive guide to traveling with young children online.
The Air Transport Association of America, which represents all the major carriers, added that "our carriers operate in full compliance with FAA's safety regulations."
The NTSB understands the FAA's view and its mandate to do a cost-benefit analysis.
"We just look at it differently than the FAA," Marshall said.
The NTSB doesn't believe that highway fatalities would increase if parents were forced to purchase additional seats. Marshall notes that after 9/11 when fewer people were flying the number of traffic fatalities did not rise. The same can be said about the last year when the global recession led to a downturn in air travel.
"We would prefer not to wait for a body count when laws of physics mandate that you need to be protected in a crash," she said. "The majority of people survive airplane accidents. So why wouldn't you want the best protection?"