A cracked windscreen forced a Delta Air Lines flight to Detroit back to mid-flight. Flight DL17 took off from the UK airport at midday on Saturday (June 7) on what would have been an eight hour flight to the city in .

But less than an hour into their journey, 188 passengers and 12 crew members found themselves travelling back to Britain after the pilot discovered a crack in the windscreen. Flightradar data shows the Airbus A330 didn't even leave UK airspace, but instead turned back to Heathrow as it was over Nottingham, according to the .

Delta Air Lines told the BBC some customers were booked onto alternative flights, with those who couldn't be offered flights on Saturday provided with hotel rooms and meals.

Heathrow Airport told the broadcaster no other flights were affected by the incident.

The carrier said the jet was being checked over and work was underway to fix the damage.

Common causes of cracked airplane windows include bird strikes, extreme swings in temperature and internal heating system faults, according to the Independent.

The cause of the Delta Air Lines cracked windscreen is unclear.

Typically, windows in a plane's cockpit are made of two or more panes with a sheet of plastic or acrylic in between, according to .

It said if one pane cracks or shatters, the other can maintain pressure in a cockpit.

Aircraft windshields are also typically 3.81cm (1.5 inches) thick and made to withstand weather and temperature extremes.

The US Federal Aviation Administration has said cracks can occur on all plane models, and they tend to be on the exterior, protective pane.

Oliver McGee, a former Professor of Mechanical Engineering at Howard University, told Simpleflying.com that an airplane windscreen crack may seem dangerous, but it actually happens more frequently than passengers might think and isn't always a cause for concern.