Horrified United passenger finds pet dog dead after a flight attendant reportedly forced her to put the animal in an overhead bin

AP

Dogs waiting to be loaded into the the cargo compartment of a plane. Not the dog involved in the United incident.

• A passenger's dog died on board a United Airlines flight Monday night.
• The incident happened after a flight attendant reportedly instructed its owner to store the pet carrier that held the dog in the overhead compartment. 
• United has apologized.

United Airlines has apologized after a passenger's dog died Monday evening during a flight. The incident took place on United Airlines Flight 1284 from Houston, Texas to New York's LaGuardia Airport.

According to an account posted to Facebook by fellow passenger Maggie Gremminger, the canine passenger belonging to a mother and her two children was being kept in a TSA-approved dog carrier. However, the owner was reportedly forced by a flight attendant to put the dog carrier along with its occupant in the overhead compartment. 

By the end of the flight, the dog was dead.

"Tonight I was on a plane where I witnessed a @united flight attendant instruct a passenger to place her dog carrier (with dog) in the overhead compartment. The passenger adamantly refused but the flight attendant went on with instruction," Gremminger said on her Facebook page. 

"At the end of the flight - the dog was found in the carrier. I am heartbroken right now. I didn't question the flight attendant, but I could have. I assumed there must be ventilation as surely the flight attendant wouldn't have instructed this otherwise. I heard the dog barking a little and we didn't realize it was barking a cry for help."

Gremminger said that the passenger was adamant about not putting her dog in the overhead bin, but the flight attendant continued to ask the passenger to put the dog in the carrier and place it in the cargo hold. 

"By the end of the flight, the dog was dead. The woman, crying in the airplane aisle on the floor," Gremminger said. 

In a statement to Busines Insider, United Airlines apologized and took responsibility for the incident:

"This was a tragic accident that should never have occurred, as pets should never be placed in the overhead bin. We assume full responsibility for this tragedy and express our deepest condolences to the family and are committed to supporting them. We are thoroughly investigating what occurred to prevent this from ever happening again."

However, the airline declined to comment on its official in-cabin pet stowage policy and whether the passengers have been compensated for their loss. 

Last August, Lulu, a King Charles spaniel, died in the cargo hold of a United Airlines jet. Earlier in the year, Simon the three-foot-long rabbit also died after a United Airlines flight.