Last April, United Airlines obliterated its customer service reputation by having a passenger dragged off an overbooked flight at O'Hare. As part of its mea culpa, here's what CEO Oscar Munoz pledged to fliers: Every customer deserves to be treated with the highest levels of service and the deepest sense of dignity and respect.

In the 11 months since, United has operated about 1.5 million flights, and surely many of them met Munoz's standard, while others fell short. Then came Monday, aboard a United flight from Houston to New York, in which a terrible decision by a flight attendant caused the death of a dog in a pet carrier.

According to reports, a puppy owner traveling with an infant and older child stowed the carrier under the seat in front of her, but apparently it didn't fit. The flight attendant's solution was to instruct the woman to stow the pet carrier in the overhead bin. The passenger protested, but the flight attendant was adamant: The dog will be fine, and your alternative is to leave the flight. On arrival, the passenger retrieved the carrier to discover her 10-month-old French bulldog was dead.

While there are details to be investigated, United failed basic tenets of caring and common sense by ordering the dog to be stowed in a compartment without adequate ventilation. The airline said it takes responsibility because "pets should never be placed in the overhead bin." Some observers may question the passenger's decision to acquiesce, but everything about this situation put the onus on the employee. Here was a passenger traveling with children and a dog ordered to comply with a safety-related instruction or be forced to leave the plane. United allows travelers to bring small pets aboard for a $125 fee.

The larger issue for Chicago-based United is how this decision violated the pledge Munoz made last year to provide great service and treat customers with respect and dignity. After the passenger disaster at O'Hare, the airline rewrote its overbooking policies but also promised to empower employees to act in the moment to put customers first. On the Houston flight, no one at the gate or onboard stepped up to protect this passenger and her dog.

Munoz is free to expound on his commitment to dignity and respect. Wary passengers can choose whether to believe him.

FROM AN EDITORIAL IN THE CHICAGO TRIBUNE