49 CFR § 175.25

General. Each person who engages in for hire air transportation of passengers must effectively inform passengers about hazardous materials that passengers are forbidden to transport on aircraft and must accomplish this through the development, implementation, and maintenance of a passenger notification system.

Passenger notification system requirements. The passenger notification system required by paragraph (a) of this section must ensure that:

A passenger is presented with information required under paragraph (a) of this section at the point of ticket purchase or, if this is not practical, in another way prior to boarding pass issuance;

A passenger is presented with information required under paragraph (a) of this section at the point of boarding pass issuance (i.e. check-in), or when no boarding pass is issued, prior to boarding the aircraft;

A passenger, where the ticket purchase and/or boarding pass issuance can be completed by a passenger without the involvement of another person, acknowledges that they have been presented with the information required under paragraph (a) of this section; and

A passenger is presented with information required under paragraph (a) of this section at each of the places at an airport where tickets are issued, boarding passes are issued, passenger baggage is dropped off, aircraft boarding areas are maintained, and at any other location where boarding passes are issued and/or checked baggage is accepted. This information must include visual examples of forbidden hazardous materials.

Aircraft operator manual requirements. For certificate holders under 14 CFR parts 121 and 135, procedures and information necessary to allow personnel to implement and maintain the passenger notification system required in paragraphs (a) and (b) of this section must be described in an operations manual and/or other appropriate manuals in accordance with 14 CFR part 121 or 135.