A United Airlines passenger was rattled after she watched a window get replaced on her flight moments before taking off ... by none other than what appears to be one of the pilots.
The passenger -- a self-described toddler expert named Kristin -- documented the experience on her IG Story Sunday ... filming what appeared to be the flight's pilot fixing the interior side of one window, this before her plane from Denver to Dallas was due to hit the sky.
She wrote ... "They are literally replacing a window with all of us just chilling and sitting here waiting to take off?!?!?!"
The incident clearly left Kristin thoroughly confused -- as she asked her Instagram followers if it was normal for a pilot to be in charge of structural repairs on the flight.
Can't blame this woman for her panic -- we know there have been several safety concerns surrounding Boeing 737 Max flights in recent months. Remember, a tire flew off a United Airlines jet back in March and an Alaska Airlines flight from January was grounded after its cabin window blew out.
While Boeing's 737 Max 9 jets were initially grounded over the safety concerns, they were given the green light by the FAA to start carrying passengers again after passing a thorough inspection ... this despite some -- including a whistleblower, who recently passed -- were trying to sound the alarm.
Thankfully, Kristin's flight had no additional issues, she confirmed she landed safely in Dallas ... so on its face, it would seem there were no further problems, with the window or otherwise.
We've reached out to United ... so far, no word back.