So far this year, 23 people have been killed and 329 injured in crashes, according to the organization's unofficial tally.
Seat belts have been required on motorcoaches in Europe and Australia since the 1990s.
Commercial bus operators fought seat belts for decades, but opposition began to weaken after a high-profile accident in 2007 in which a bus carrying Ohio's Bluffton University baseball team plummeted off a highway overpass near Atlanta. Five players, the bus driver and his wife were killed. Twenty-eight others were injured, including some students who are still trying to put their lives back together seven years later, said John Betts of Bryan, Ohio, whose son, David, was among those killed.
Bus manufacturers have recently begun including seat belts on most new buses anyway, said Dan Ronan, a spokesman for the American Bus Association.
But buses are typically on the road for about 20 to 25 years. Even if the government were to issue regulations tomorrow, it would likely be years before all have safety enhancements.
The industry opposes requiring that existing buses be retrofitted with seat belts. Seats not designed for them may not be strong enough to withstand the repeated pulling of straps, it says. Retrofitting is also more expensive than adding belts to new buses.
Generations of buses have come and gone without seat belts since the 1968 accident on a Mojave Desert highway near Baker, Calif., that prompted NTSB's first recommendation. In that collision, autopsies later showed most of the passengers survived the crash, but were badly injured and unable to escape the fire. If the bus had seat belts, it is likely that more passengers would have escaped because their injuries would have been less severe and they would have been less disoriented, the safety board said.
"We have worked too hard for too long for such a common-sense thing to be held up by people that don't see it as significant," said Betts, who lobbied to get the legislation passed. "If their son or daughter or wife or husband were killed in a motorcoach accident, perhaps that would get it off their desk."
Follow Joan Lowy on Twitter at http://www.twitter.com/AP_Joan_Lowy
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