This is the amusing moment a pet Saint Bernard was spotted relaxing on a plane with its own seat.

A family aboard Air China brought Xiong Er, their four-year-old trained service dog, on a holiday trip to Harbin, Heilongjiang, on March 18.

Footage shows the well-behaved canine onboard the Boeing 737 lying calmly on the floor next to the aisle while curious passengers watch in fascination.

The pet owner said: 'Xiong Er is a very gentle and well-trained dog. We're grateful the airline allowed us to bring him into the cabin so he could rest and enjoy the flight.'

Chinese airlines generally prohibit pets in the cabin, except for trained service animals. Other pets must be transported as checked baggage in the cargo hold in an appropriate travel container.

Saint Bernards excel as trained service animals, providing mobility assistance, therapy, and medical alert support due to their gentle temperament, strength, and intelligence.