United Flight UA938 Shut Down an Engine Over the Atlantic and Landed at Shannon on the Other One

United Airlines flight UA938, a Boeing 767-300ER flying from Chicago O’Hare to London Heathrow, declared a Mayday over the Atlantic on the morning of September 21, 2026, and diverted to Shannon Airport in Ireland. The crew reported a problem with the left engine and shut it down.

The jet landed safely at Shannon at 11:18 a.m. local time with 173 passengers and crew on board, and was escorted to the terminal by emergency vehicles.

What happened on UA938

The overnight flight left Chicago at 10:51 p.m. local time on September 20, according to FlightAware tracking data. It was just over five hours into the trip, approaching Ireland from the west, when the crew made the emergency call shortly after 10 a.m. Irish time.

The crew told air traffic controllers they had an issue with the left engine and had shut it down, Clare FM reported. Shannon Airport’s own fire service was joined by Clare County Fire and Rescue crews from Shannon town, with an Ennis unit held at a staging point on the M18 motorway.

The National Ambulance Service and the Gardaí were also alerted. After the landing, the ambulance service was stood down at 11:45 a.m., the Clare Herald reported.

Emergency crews inspected the left engine on the ground at Shannon. A replacement aircraft was due to fly in from London later in the day to carry passengers on to Heathrow. United had not publicly explained the cause of the failure at the time of writing, and the aircraft’s registration has not been published.

Why a 767 can fly to Shannon on one engine

A Mayday call is the highest level of distress call a crew can make. It gets the flight immediate priority from controllers and puts rescue services on standby, even when the crew expects to land normally.

Losing one engine on a twin-engine airliner is serious but planned for. Under FAA rules, any two-engine passenger jet that flies more than 60 minutes from a suitable airport at one-engine cruise speed needs ETOPS approval, which is why twin-engine jets crossing the North Atlantic fly under it.

ETOPS means the airline has shown the aircraft, its maintenance program and its flight planning can safely reach a diversion airport on the remaining engine. Each ETOPS flight is dispatched with named ETOPS alternate airports, and the crew is kept updated on their weather during the crossing, so it knows where to go before anything goes wrong.

For flights approaching Europe from the west, Shannon Airport is one of the closest options. It sits on Ireland’s Atlantic coast, one of the most westerly international airports in Europe, and its runway is 10,495 feet (3,199 m) long, the longest in Ireland.

A busy summer for United’s 767 fleet

UA938 is not the first United 767 to turn to Shannon with an engine problem this summer. On July 11, United flight UA509, a 767-400ER flying from Rome to Newark, diverted there after its right engine failed. A passenger described a hole “the size of a bowling ball” in the engine, Simple Flying reported.

In August, a United 767 lost an engine over France and returned to Geneva. The Boeing 767-300 has flown United’s long-haul routes since 1991.

Nothing published so far links the three events, which involved different routes and, on UA509, a different 767 variant. What caused the UA938 failure will depend on the engine inspection now underway in Shannon.