A United Airlines Boeing 757 was forced to divert twice in a row due to reported engine issues. On both occasions, the aircraft was operating a transatlantic flight from Dublin to Washington, DC, but had to make emergency landings, first at Dublin Airport (DUB), and then, on the second attempt, at Shannon Airport (SNN).
Flightradar24.com data shows that on both occasions, the airline’s Boeing 757-200 covered a similar flight distance before diverting. The first diversion to Dublin Airport occurred on September 17, 2025, while the second took place two days later, on September 19, 2025. Due to reported engine issues, the flight scheduled for September 18, 2025, was canceled, the airline confirmed to Simple Flying.
A Closer Look Into The First Diversion
On September 17, 2025, the United Airlines Boeing 757-200 aircraft, registered as N17133, was operating a scheduled transatlantic flight UA 711 from Dublin Airport (DUB) to Washington Dulles International Airport (IAD) when the flight crew decided to return to DUB due to an engine problem.
The aircraft landed safely more than three hours after departure and was subsequently parked at Dublin Airport for maintenance. ch-aviation data indicates that the 26.8-year-old Boeing 757 was ordered by United Airlines in 1997 and, as of January 31, 2025, had accumulated a total of 97,769 flight hours and 20,799 flight cycles.
In a comment to Simple Flying, a United Airlines spokesperson confirmed the incident, adding that a total of 46 passengers and six flight crew members were onboard the aircraft. It is worth noting that the aircraft can accommodate 176 passengers in a three-class cabin configuration: 16 in business class, 42 in economy plus, and 118 in economy class. The United Airlines spokesperson added:
“The flight subsequently canceled, and we worked to get customers to their destination as soon as possible.”
Diversion To Shannon Airport
After canceling the September 18, 2025 flight, the Chicago-based airline resumed operations with the same Boeing 757-200 on September 19, 2025. However, the flight’s final destination was changed from Washington Dulles International Airport (IAD) to Newark Liberty International Airport (EWR). Despite this, the flight UA 3901 was once again forced to divert to Shannon Airport (SNN) due to mechanical issues.
The spokesperson for the carrier told Simple Flying that no passengers were on board, only the flight crew. Passengers originally scheduled to travel to Washington on September 17, 2025, were accommodated on alternate flights. The airline also provided hotel accommodations and meal vouchers to affected passengers.
According to flight tracker data from Flightradar24.com, the airline’s Boeing 757-200 aircraft remains at Shannon Airport (SNN), Ireland, awaiting departure to Newark Liberty International Airport (EWR). The flight is scheduled to take off at 17:47 local time in Ireland.
Other Reasons Flights Are Diverted
There are many reasons why an aircraft may land somewhere other than its planned destination, including weather. The most significant factor is the condition at the destination airport. Although this is checked before departure, conditions can change during a long flight, especially if a storm develops.
Technical issues with the aircraft are another common reason for diversions. Any serious problem may require the aircraft to land sooner, with the severity of the issue determining how urgently this must happen. Diversions can also occur due to medical emergencies or unruly passengers. If the crew cannot handle a medical situation onboard, flights will often land to obtain medical assistance. Similarly, if there is a threat to the aircraft, passengers, or crew, the flight will usually divert.
Other unpredictable events can affect flight plans, such as airport closures, ground conflicts, or security threats. A notable example is the events of September 11, 2001, when all aircraft in U.S. airspace were ordered to divert and land.