US Airways apologizes for posting an inappropriate image to a customer. (Posted April 15, 2014)

Ladies and gentlemen, the fasten seat belt sign is on. We're experiencing some severe Twitter turbulence. 

Think of the most lewd, embarrassing, shocking and offensive pornographic photo, one you'd never want another person to know you've looked at.

Now imagine working on social media for US Airways and sharing that photo with more than 420,000 people on Twitter in response to a customer complaint.

It happened Monday afternoon, and some are calling it the worst tweet ever shared by a brand in the history of Twitter. By Tuesday morning, the tweet @USAirways sent apologizing for the mishap was retweeted more than 13,000 times and had more than 10,000 favorites.

It's as bad as it sounds. The photo, which we won't show or link to because we can't, depicts a toy Boeing 777 jet and a naked woman in a very compromising position.

It started when Twitter user @ElleRafter complained about her plane sitting on the tarmac, resulting in a delay getting to her destination. US Airways sent its response in a tweet: "We welcome feedback, Elle. If your travel is complete, you can detail it here for review and follow-up." But the here, which was probably supposed to be a link to the company's customer service page ended up being a link to the obscene photo, which showed up in a big way on the Twitter feed.

It took US Airways a while to take the extremely NSFW tweet down, and a section on its Twitter page that shows recent photos kept the photo up even longer.

The photo and subsequent tweets gave birth to several NSFW hashtags and made the company's gaffe the number one trending topic in the United States for several hours, despite it happening just as the Pulitizer Prizes were being announced.

US Airways issued a full apology, but Twitter is laughing at the apology almost as much as the original tweet.

"We apologize for the inappropriate image we recently shared in a Twitter response. Our investigation has determined that the image was initially posted to our Twitter feed by another user. We captured the tweet to flag it as inappropriate. Unfortunately the image was inadvertently included in a response to a customer. We immediately realized the error and removed our tweet. We deeply regret the mistake and we are currently reviewing our processes to prevent such errors in the future."

The "initially posted to our Twitter feed by another user" is in reference to someone tweeting it earlier to @AmericanAir. US Airways and American Airlines are in the process of merging.

Tuesday afternoon, a spokesman told the New York Daily News that the person responsible for what it called "an honest mistake" will not be fired.

Until this incident, US Airways' biggest brush with Twitter fame came in 2009 when Flight 1549 landed safely in the Hudson River after it struck a flock of Canada Geese.