4-hour flight to nowhere for passengers headed to Miami after a pilot became unwell

• A Swiss International Air Lines pilot started feeling unwell mid-journey.
• The flight from Zurich to Miami then turned around over the Atlantic.
• A return flight from Florida to Switzerland was also canceled because the aircraft was diverted.

Swiss International Air Lines passengers endured a four-hour flight to nowhere after a pilot fell ill.

Two hours after flight LX66 left Zurich for Miami on Monday, it U-turned over the Atlantic Ocean about 300 miles off the French coast, according to Flightradar24 data.

"One of the pilots did not feel fully fit after starting the flight," an airline spokesperson told Business Insider. "As a precautionary measure, the cockpit crew decided not to continue the flight and instead returned to Zurich Airport."

There were 123 passengers on board the flight, which landed back in Zurich at 2:24 p.m. local time — some four hours after departure.

The Swiss spokesperson added that the fire department was standing by, which was standard procedure given that the Airbus A330 was landing at a higher-than-normal weight.

The aircraft had enough fuel for a 10-hour flight, but lacked a fuel-dump system.

A diverted flight is not only frustrating for the passengers on board, but can also have knock-on effects on other journeys. People scheduled to fly on the same A330 from Miami to Zurich later on Monday had their flight canceled.

"We have rebooked the affected passengers onto alternative connections and would like to sincerely apologize for the inconvenience caused," the airline spokesperson said.

They added that Swiss would cover expenses for passengers' hotel accommodations, taxi rides, meals, and phone calls until the next possible departure, rebook free of charge, or cancel the trip with a full refund.