Well unless the crew are trained then the device can't be used for critical stages of flight, Takeoff, landing etc. ultimately it's the pilots responcibility to make sure seatbelts are approved, its part of the COA (certificate of Airworthiness) of the aircraft, this has to be carried in a fire resistant pouch on all flights. As the belt is only approved with crews training it can not be used, (for critical stages of flight) unless the airline has accepted it, and trained their staff.