A Delta Air Lines plane was forced to U-turn because of a passenger's diarrhea. Here are 6 other unusual reasons that can delay or divert a flight.

06.09.2023 - 10:15 / insider.com / Delta Air / Airlines

Whether it's disruptive passengers, weather issues, fuel shortages, or medical concerns, commercial flights can often divert or turn around for technical or health-related reasons.

But in recent years, some pilots have made the decision to land for seemingly unlikely circumstances. On Friday, a Delta Air Lines flight was forced to turn around due to a passenger's diarrhea, which left a trail of poop on the aisle that the pilot told flight control was a "bio-hazard."

Here are six unusual reasons that can cause flights to turn around.

Sometimes, smells can become unbearable enough for passengers and crew that a flight is forced to U-turn.

In October, an American Airlines Boeing 737 flying from Miami to Barbados returned to Miami International Airport because of a "chemical odor in the cabin caused by the contents of a customer's carry-on luggage," The Independent reported.

Some cabin crew and passengers were evacuated by emergency services because they fell sick from the fumes in the luggage, per the outlet. They were sent to hospital out of an "abundance of caution," an airline spokesperson said, according to The Independent.

Even the smell of cannabis was enough to divert a British Airways flight traveling from London to Crete in 2016, per The Evening Standard. The flight's 174 passengers were diverted over Paris and sent back to London to wait for a replacement flight, the outlet reported.

However, an airline spokesperson told the outlet that no cannabis was found on board.

In April, 300 people on board an Austrian Airlines Boeing 777 had to turn back two hours into their journey from Vienna to New York because five of the plane's eight toilets wouldn't flush, AFP reported.

Jammed toilets are a typical reason for passenger flights to divert to the nearest airport.

One 2016 British Airways flight to Dubai, however, suffered perhaps the most drastic plane toilet horror story.

The flight had to return to London's Heathrow Airport due to what passengers said was a "smelly poo" in the toilet, The Telegraph reported.

One man on board, Hertsmere councilor Abhishek Sachdev, said the pilot had called for senior cabin crew to discuss a matter with him. "About 10 minutes later he said you may have noticed there's a quite pungent smell coming from one of the toilet," Sachdev said, per the BBC.

The plane was diverted 30 minutes into its seven-hour trip, according to the outlet.

Bird strikes aren't rare on commercial flights. At least 272,000 wildlife strikes have been reported by civilian aircraft in the US between 1990 and 2022, the vast majority of which involve birds, per the Federal Aviation Administration. 

Planes are more likely to encounter birds when taking off, landing, climbing in the air, or