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United Airlines Boeing 787 Dreamliner Returns To Chicago Over Potential Pressure Issue


  • A United Airlines flight recently diverted back to Chicago after a cooling system was detected onboard.
  • The aircraft made a U-turn two hours into the flight, reducing speed and descending to a lower altitude.
  • The airline deployed another plane to complete the original flight to Barcelona, but passengers were delayed over12 hours.

A Boeing 787-8 Dreamliner operated by United Airlines diverted to Chicago after the crew detected a cooling system problem during a flight to Barcelona earlier this month. The aircraft, which had reached its cruising altitude before the issue, descended and landed safely.

The flight originated at Chicago O’Hare International Airport (ORD) but returned after being airborne for over five hours. Mechanics solved the problem fairly quickly, as the aircraft returned to service on the same day.

Turning around 2 hours into the flight

According to The Aviation Herald, the plane, registered as N27901, was operating UA769 from ORD to Josep Tarradellas Barcelona–El Prat Airport (BCN) on September 9th. The 787 was scheduled to depart from gate C18 at 21:20 but did not push back until 21:27, according to data from At 21:48, the aircraft took off from Runway 9R and headed northeast over Lake Michigan.

United 787

Photo: Vincenzo Pace | Simple Flying

The plane climbed to an initial cruising altitude of 35,000 feet before jumping to 39,000 feet over east Michigan. N27901 continued to travel northeast and flew over the Gulf of St. Lawrence just past Anticosti Island. Two hours and 34 minutes into the flight, data shows the aircraft making a U-turn at 39,000 feet and drastically reducing its speed. According to FlightAware, the plane slowed from 626 miles per hour (mph) to around 490 mph before descending to 34,000 feet.

Possible pressurization issue

NAV Canada, the corporation that runs Canada’s civil air navigation system, confirmed that the crew “advised they needed to turn around due to a cooling system issue that could turn into a pressurization issue,” according to The Aviation Herald. The company also said the pilots advised that they could fly below 35,000 feet without any issues.

Nearly three hours into the flight, the aircraft was headed southwest back toward Chicago. Two hours later, the crew began an initial descent to 32,000 feet and maintained the altitude for about 10 minutes before descending further. The plane approached ORD from the northeast and flew past the airport to the west to line up for its final approach.

Returning to ORD

At 03:27 CDT, N27901 was at 5,400 feet, turned south, and descended to 3,800 feet. Minutes later, the aircraft was on final approach for Runway 10C and landed safely at 03:35, according to FlightAware. It reportedly arrived at gate C16 at 03:45, over six hours after it had pushed back.

United Airlines Boeing 787-8 Dreamliner N26910(2)

Photo: Vincenzo Pace | Simple Flying

According to The Aviation Herald, United deployed N27903, another 787-8 to complete the flight to BCN, but passengers had to wait most of the day. The aircraft departed ORD from gate C20 at 21:38 on September 10th, over 12 hours after N27901 had arrived. FlightAware indicated N27903 arrived at BCN at 12:18 on September 11th after flying for around eight hours.

It is unclear how soon United could repair the cooling system issue on N27901, but it appeared to be a minor fix. The aircraft performed UA416 from ORD to Milan, Italy, the same evening N27903 completed UA769 to BCN. The two flights departed about 15 minutes apart.

Sources: The Aviation Herald,, FlightAware (1,2,3)


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