A couple is being investigated by the FBI after an alleged attempt — and failure — at joining the infamous "Mile-High Club"  Sunday. The man and woman were strangers upon boarding a Delta Air Lines flight heading from Los Angeles to Detriot, according to reports. 

A 48-year-old woman was seemingly caught performing oral sex on a 28-year-old man while they were in their seats. The woman was in route to Nashville, whereas the man was heading to Miami. Both passengers were issued citations by the FBI for their actions, but they could walk away with anything between a misdemeanor or a criminal charge. 

"The act itself is inappropriate in a public space," one passenger told NBC affiliate WDIV Monday. 

An FBI spokesperson claimed that they would not be able to provide comment on "open or ongoing investigations, but broadly I can say we do investigate crimes aboard aircraft, once the boarding door closes, regardless of severity," according to a statement issued to the Detroit Free Press Tuesday. 

Sex on airplanes is said to be a very common occurrence. Almost 80 percent of the sexual conduct occurs within coach, according to a survey conducted by Stratos Jet Charters in 2016.  The study, which examined 2,000 passengers, found that 79 percent have confirmed that they have participated in the act with a significant other. Only 20 percent of respondents claimed to have spent time with a complete stranger. 

A representative for Delta Air Lines did not immediately return International Business Times request for comment.