NEW YORK: United Airlines, under siege over the death of a puppy on one of its flights, says the flight attendant who ordered a passenger to put her pet carrier in the overhead bin didn’t know there was a dog inside. The airline’s account was contradicted by the family that owned the French bulldog, and also by other passengers on Monday night’s flight. Eleven-year-old Sophia Ceballos told NBC News that her mother told the flight attendant “’It’s a dog, it’s a dog, and (the flight attendant) said we have to put it up there,” in the bin. Other passengers backed up the family’s account on Twitter and Facebook. United said Wednesday acknowledged that the customer said there was a dog in the carrier. “However, our flight attendant did not hear or understand her, and did not knowingly place the dog in the overhead bin,” the airline said in a statement. United declined to identify the employee. Last year, 18 animals, mostly dogs, died while being transported on United — three-fourths of all animal deaths on US carriers, according to the Department of Transportation. Those figures represent animals that die in cargo holds. It is rare that an animal dies on a plane. Even on United there was only one death for roughly every 4,500 animals transported last year. United, which promotes its pet-shipping program called PetSafe, carries more animals than any other airline, but its animal-death rate is also the highest in the industry. Alaska Airlines, which carries only 17 percent fewer animals, had just two deaths last year.