Worried United Airlines passenger films PILOT replacing window before flight from Dallas to Denver

A mother on board a United Airlines flight from Dallas to Denver was concerned after seeing the plane's pilot replacing a window just before the aircraft took off. 

Kristin Gallant, 37, is the founder of Big Little Feelings - a due of 'toddler experts' who have 3.4 million followers on Instagram.

Gallant shared a worrying video on her Instagram story on Sunday captioned: 'They are literally replacing a 'window' with all of us just chilling and sitting here waiting to take off?!?!?'

In the video, a man who was wearing a pilot's uniform was scrambling to jam the oval shaped window back into its slot.

He was clearly struggling to wedge the window back into place - which deeply worried Gallant, who was flying with her three young children, all under the age of seven. 

A mother on board a United Airlines flight from Dallas to Denver was concerned after seeing the plane's pilot replacing a window just before the aircraft took off

In the video, a man who was wearing a pilot's uniform was scrambling to jam the oval shaped window back into its slot

The mom-of-three shared an update with her millions of followers, saying 'I have so many questions. Is this our pilot? Should a pilot be replacing a f***ing window? Is this normal?'

The mom-of-three shared an update with her millions of followers, saying 'I have so many questions. Is this our pilot? Should a pilot be replacing a f***ing window? Is this normal?'

United Airlines told DailyMail.com: 'The video shows a ring of plastic called a bezel, which is cosmetic and not required for the safe operation of the aircraft.' 

Gallant's concern was warranted, considering the fleet of scary incidents on Boeing aircrafts recently. 

Just days ago, a Southwest Airlines flight was forced to return to the Denver International Airport early Sunday after the engine cowling fell off the Boeing 737 and hit the wing flap during takeoff.

The early morning flight was on its way to the William P. Hobby Airport in Houston when passengers and crew realized the cowling had torn off and was flapping precariously against the plane.

A cowling is a removable metal covering on the engine.

Horrifying video showed the plane parts flapping in the wind as the plane moved through the air. It's the latest in a string of bad publicity and massive safety fears for the beleaguered airline.

The plane returned safely to the Denver airport around 8.15am after the incident. It had departed the gate at 7.39am.

A Southwest Airlines flight made an emergency return to the Denver Airport Sunday morning after a Boeing 737's engine bowling blew off shortly after takeoff

A United Airlines plane built by Boeing was grounded last month after it was found to be missing a panel after it touched down following a flight. Pictured: The missing part on the 25-year-old Boeing 737-824

Concerns were sparked after a door flew off a Boeing 737 MAX , leaving a gaping hole in the side of aircraft, on January 5 

On Friday, a United Airlines plane built by Boeing was grounded after it was found to be missing a panel after it touched down following a flight.

The plane is a Boeing 737-824, and successfully touched down in Medford Airport in Oregon despite the missing part.

Concerns were sparked after a door flew off a Boeing 737 MAX, leaving a gaping hole in the side of aircraft, on January 5.

The preliminary report on the incident from the National Transportation Safety Board offered the clearest evidence yet that a significant manufacturing error led to the near-tragedy. 

A newer report found that four retaining bolts intended to prevent vertical movement of the door plug were missing, and suggests that Boeing workers failed to replace them after removing the plug for a repair during assembly.

The damage patterns observed in the door plug and airframe indicated that the four bolts were not in place at the time of the incident, allowing the plug to detach from the stop pads.