United passengers heading to Newark ended up in Dublin after a mid-Atlantic medical issue

• A United Airlines flight from Amsterdam to Newark diverted to Dublin.
• The airline told Business Insider it was due to a "health concern."
• One aviation outlet reported that one of the pilots had chest pains.

A transatlantic United Airlines flight had to divert to Dublin due to a medical emergency.

The Boeing 777 was flying from Amsterdam to Newark Liberty International Airport on Tuesday.

Just over an hour into the journey, it circled a few times over the Scottish Highlands before continuing, according to data from Flightradar24.

An hour and a half later, Flight 71 was over the Atlantic Ocean and around 200 miles south of Iceland when it U-turned.

It landed in Dublin about four hours after taking off from Amsterdam. A direct flight between the Irish and Dutch capitals usually takes around an hour and a half.

A United Airlines representative confirmed to Business Insider that the plane diverted to "address a health concern." Dublin Airport declined to comment.

The Aviation Herald reported that one of the pilots had a medical emergency as they experienced chest pains.

Data from Flightradar24 shows the same Boeing 777 took off from Dublin an hour and a half after landing there. It landed in Newark shortly before 4 p.m. local time — having previously been expected to arrive around 11 a.m.

A pilot suffering a mid-flight medical issue is rare but not unheard of.

Last December, an off-duty pilot stepped in to help fly a WestJet Boeing 737 when the flight's first officer was suddenly incapacitated mid-flight.

Last July, an easyJet flight was met by paramedics upon landing in Lisbon after one of the pilots fainted during the flight.