The NTSB last month asked regulators to require children to have their own seats and seat belts, but the FAA squashed that idea back in 2005, citing statistical data, and may do so again. The new call (specific to commercial aircraft, though relevant to small aircraft) is tied to a March 2009 crash of a Pilatus PC-12/45 that had been configured to seat 10 but crashed killing all 14 that were actually loaded aboard. Seven of those aboard were children and several appeared to have been thrown from the aircraft after initial impact. The crash itself was severe enough that it's unlikely anyone would have survived regardless of seating choice. But the FAA agrees that infants and toddlers are safest in their own seat using a child-specific approved restraint like those approved in 2006. But in the larger picture, the agency believes applying the requirement (buying an extra seat on a commercial airline for a small child) would ultimately drive more travelers to other, statistically less safe, modes of transportation.
In 2004, 43,000 people were killed while traveling by road versus 13 who were killed aboard commercial flights (see FAA news release, here). The number is down for 2009 to 33,808, which is the lowest since 1950, according to the Transportation Department. Clearly the number of people involved and the number of hours spent on either endeavor affects the final totals. But the FAA says that requiring parents to purchase seats for small children would put many more of those people on the nation's highways as they sought to avoid added the cost of purchasing an extra seat. And that, it says, could result in anywhere from 13 to 42 more deaths over a 10-year period. View the NTSB's recommendation here (PDF). For general aviation pilots, the decision may be more flexible, but the same advice on restraints (and approved devices) may still be applied.