A United Airlines flight between Zurich and Chicago was forced to divert to London Heathrow Airport on Sunday, November 23, following reports of cabin fumes being experienced onboard. This resulted in a number of passengers and crew falling ill, forcing the diversion to one of Europe’s busiest airports.

The Zurich to Chicago flight, which usually takes around ten hours and 30 minutes gate to gate, was approximately 60 nautical miles (69 miles / 110 km) north of London when the captain decided, out of an abundance of caution, to divert to London, for the safety of all the passengers and crew onboard. The flight landed just 30 minutes after this decision was made.

Fumes Onboard

United Airlines was operating a scheduled flight as UA12, one of its daily flights between Zurich Airport (ZRH) and Chicago O’Hare International Airport (ORD). The flight, which is operated by the 767, was scheduled to depart from the busy Swiss airport at 09:40 am; however had experienced delays on departure on November 23, resulting in the aircraft only becoming airborne around 10:20 am as per Flightradar24.

During the flight, it appears, as per a report by AvHerald, that fumes were identified onboard, which led to a number of passengers and crew becoming unwell. This led to the pilot making the decision to divert to London, and the subsequent flight was cancelled.

Simple Flying reached out to United Airlines for comment; however, they didn’t immediately respond by the time this article was published.

UA12 Cancelled

The service, which was due to arrive in the Windy City (Chicago) that same day at 12:45 noon, touched down in London just two hours and 25 minutes after take-off from Zurich. The onward flight was cancelled, forcing passengers and crew stranded in London to be accommodated in a hotel and meal vouchers overnight before traveling the next day.

A replacement flight was put on the following morning, operating on Monday, November 24, departing from London Heathrow at 11:40 am, arriving in Chicago at 14:13 that same day, resulting in an overall delay of around 26 hours for those travelling on the service. The aircraft at the centre of the diverted flight, N665UA, was subsequently checked over by maintenance personnel on the ground at LHR and eventually cleared for service. This aircraft also operated the rescheduled flight UA3908 the following morning.

Before operating the flight from Zurich to Chicago, the airline had operated the outbound service from Chicago to Zurich, under UA3, without any major issues apart from a 90-minute delay. The aircraft had departed from ORD on November 22 at 5:40 pm (instead of 4:10 pm), and arrived in Zurich at 08:21 am the next morning (instead of 7:55 am)

N665UA

The aircraft involved (pictured above) is 27.4 year 27.4-year-old 767-322E, serial number 29237. The aircraft took its first test flight on July 16, 1998, and has been a loyal servant to the Star Alliance carrier since its delivery to the airline on July 27, 1998. According to data from ch-aviation, the airplane is powered by two Pratt & Whitney PW4060 engines and is configured to carry up to 167 passengers spread across three classes of service (46 business, 22 premium economy, and 99 economy class seats).

Upon arrival back to Chicago, the aircraft appears not to have been out of service for long, resuming regular scheduled services later that day. The aircraft flew as UA920 on November 24 between O’Hare and London Heathrow, pushing back from ORD at 7:11 pm (one hour and 21 minutes behind the scheduled departure time of 5:50 pm), and arriving in London at 08:40 the next morning (versus the 7:55 am scheduled arrival time). The aircraft is expected to travel as UA921 to Newark Liberty International Airport (EWR) later this evening local time (6:00 pm).

This aircraft has been in hot water a few times before, with Simple Flying reporting on the incident where the airplane was traveling from London Heathrow to Newark Liberty International Airport on March 26 and experienced engine failure, forcing the aircraft to return to the British capital. This flight was scarcely full, with just 70 passengers and 11 crew onboard (representing just 41.9% occupancy). Passengers affected on this flight were re-booked onto an alternative service.