A 71-year-old United Airlines passenger was left unconscious after asking an airport worker to print a new boarding pass for him, according to a $1million lawsuit.
Frequent flier Ronald Tigner claims he spoke to UA worker Alejandro Anastasia at George Bush Intercontinental Airport in Texas and was knocked out cold in the moments that followed.
Shocking CCTV footage shows the pensioner being shoved and falling onto his back - and not one employee rushes to his aid in the minutes that followed, his lawyer says.
The lawsuit comes after footage of Dr David Dao being violently removed from an overbooked flight in Chicago went viral and wiped $1billion from UA's share price.
William Hoke, Mr Tigner's lawyer, told KPRC: "This is just one of the most inhumane things I've ever seen in my life .
Anastasia shoves the pensioner and he tumbles to the floor
The thug calmly walks away afterwards
"Anastasia was looking at Mr Tigner and started smiling and said 'can't you see we're busy?' and there's no one in the vicinity of these two employees.
"And he tells Anastasia to wipe that smile off his face. That's when Anastasia says 'I'll kick your (expletives)' and shoves Tigner to the ground."
The incident came in 2015 and the employee involved no longer works for the airline
The altercation came in 2015 after Mr Tigner asked Anastasia to print a new boarding pass for him because his was "garbled".
An off-duty nurse eventually rushed over to the pensioner's side and an airport worker who called 911 claimed not to know the cause of his injuries, according to the lawsuit.
A United Airlines spokesman said: "We have seen the video from 2015 that shows completely unacceptable behavior by a United employee.
Dr David Dao was left bloodied after rough treatment at the hands of United Airlines staff
"This employee is no longer with our company. The conduct shown here does not reflect our values or our commitment to treat all of our customers with respect and dignity.
"We are taking a thorough look into what happened here and reaching out to our customer to profusely apologize for what occurred and to make this right."