United Airlines has again been sued by a passenger for mistreatment, after he was pushed to the floor by a United employee in 2015 at George Bush Intercontinental in Houston. The airline issued an apology, but only after video of the episode was made public. The Houston television station KPRC broke the story Tuesday when it obtained the surveillance video, from July 21, 2015, showing a customer service agent shoving a 71-year-old man to the floor near check-in kiosks. The video shows the man lying motionless and unattended despite the presence of several United employees in the area. After nearly a minute, another passenger approaches and tells the employees to call 911. The episode began when the man requested a new boarding pass, saying that the original was illegible, but was denied by the airline. <br/>