I do not know the strength rating requirement for an aircraft seatbelt, but I would be surprised if it was little different to automotive seatbelt strength ratings.
Onetrack,
Quite different, actually, which makes the CASA ban on car seat belt material such a steaming great joke. It is quite inferior to automotive material.
Last time I looked, all that as required was to demonstrate a 1000lb load, steadily applied, no allowance for shock loading, a twisted belt or any wear or damage.
Tootle pip!!