Woman on United Airlines Flight Says She Was Forced To Sit Next To Masturbating Man

A woman says she was trapped next to a guy who was pleasuring himself aboard a United Airlines flight ... and, so far, the man has gotten off scot-free.

The 25-year-old woman told NBC News she was seated next to the man on a flight from Rochester, New York, to Newark Liberty International Airport in New Jersey on September 3 when things suddenly got X-rated.

She said the "unassuming" and "pretty normal looking" 35-to-40-year-old man started masturbating right in front of her ... all while staring at her.

The woman told NBC ... "I just got the sense [he] had done it before ... People don't just do those things at 6 AM."

She said she promptly reported the incident to flight staff, who allowed her to leave her seat until it was time to land. The plane was full, so she had to stand in the aisle to get away from the alleged masturbator.

The woman also said flight attendants promised her she would only have to sit next to the dude for about 5 minutes until they landed ... but it turned out to be a lot longer.

Even worse, the woman said once they landed, the man exited the plane and disappeared without facing the music.

She said United Airlines provided her with a measly $100 flight credit ... even though the total cost of her trip was $400.