Ar cle 816 A passenger who is unable to get on board at the me indicated in the cket due to his own reason shall, within the period of me agreed by the par es, undergo the procedures for refund or change of the cket. If the passenger fails to undergo the refund or change procedures within the agreed period of me, the carrier may refuse to refund the cket, and no longer has the transport obliga on. Ar cle 817 The carry-on baggage of a passenger shall conform to the quan ty limit and category requirement in accordance with the agreement. A passenger who carries baggage in excess of the quan ty limit or in viola on of the requirements for the category shall have the baggage checked in. Ar cle 818 A passenger may not carry with him or secretly carry in his baggage any in ammable, explosive, toxic, corrosive, or radioac ve ar cles, any other dangerous ar cles that might endanger the safety of persons and property aboard, nor any contraband ar cles. Where a passenger violates the provisions of the preceding paragraph, the carrier may unload or destroy the dangerous or contraband ar cles or deliver them to the relevant departments. Where a passenger insists on carrying with him the dangerous ar cles or the contraband ar cles or carrying them in his baggage, the carrier shall refuse to transport him. Ar cle 819 A carrier shall strictly ful ll his obliga on of safe transport and mely no fy passengers about ma ers of a en on for a safe transport. A passenger shall ac vely assist in and be coopera ve with the carrier with regard to the reasonable arrangements made for safe transport. Ar cle 820 A carrier shall transport passengers at the me and in the number of runs or ights and seat number indicated in the valid cket. Under circumstances where the transport is delayed or rendered out of a normal state, the carrier shall inform and remind the passenger in a mely manner, take necessary measures for arrangement, and, upon passengers' requests, arrange them to take other numbers of runs or ights or refund their ckets. The carrier shall bear the liability for compensa on for any loss thus caused to the passenger, unless such loss is not a ributable to the carrier. Ar cle 821 A carrier who unilaterally downgrades the service standard shall, upon passengers' requests, refund their ckets or reduce the fare. A carrier who upgrades the service standard shall not charge extra fare. Ar cle 822 A carrier shall, in the course of transporta on, spare no e ort to rescue and help a passenger who su ers an emergent disease, commence childbirth, or otherwise in danger. Ar cle 823 A carrier shall bear the liability for compensa on arising from the injury or death of a passenger occurring in the course of transporta on, unless the injury or death is a result of the passenger's own health condi on, or the carrier can prove that the injury or death is caused by the passenger's inten onal or grossly negligent act. The provisions of the preceding paragraph shall apply to any passenger exempted from cket in accordance with the regula ons, holding a complimentary cket, or permi ed by the carrier to travel without a cket. Ar cle 824 Where an ar cle that the passenger carries with him is destructed, damaged, or lost in the course ti ti ti ti ti ti fl fl ti ti fl ti ti ti ti ti ti ti ti ti ff ti ti tt fi ti ti ti ti ti ti ti ti ti ti ti ti ti tt ti ti fi ti ti ti ti ti ti ti ti ti ti ti ti tt ff ti ti tt ti ff ti ti ti ti ti ti ti ti 88 ti ti fl Ar cle 815 A passenger shall get on board pursuant to the me, the number of runs or ights, and the seat number indicated in the valid cket. Any passenger who boards without a cket, beyond the paid distance, in a higher class, or with a discounted cket while he is unquali ed therefor shall pay or make up for the di erence in the cket price, and the carrier may charge an extra fare according to the regula ons. Where a passenger refuses to pay the fare accordingly, the carrier may refuse to transport him. Where a passenger under a real-name passenger transport contract loses his cket, he may request the carrier to report the loss and reissue a cket, and the carrier shall not re-collect cket fees or other unreasonable expenses.