Delta Flight to Boston Diverted to Porto After Smoke Reported in Cabin

A Delta Air Lines flight headed to Boston from Barcelona was diverted to Porto, Portugal, on Sunday after smoke was detected in the cabin, disrupting travel for more than 280 passengers.

Fourteen passengers required medical attention after the plane landed, according to Portugal’s civil protection service, as reported by Agence France-Presse. Four of those passengers were taken to local hospitals for smoke inhalation, described as only “lightly” affected.

A Delta spokesperson confirmed the Sept. 27 incident, attributing the diversion to a “reported mechanical issue,” but did not comment further on the hospitalizations.

“The flight landed safely, and we apologize to our customers for the delay in their travels as we work to get them to Boston as safely and quickly as possible,” the spokesperson said.

The aircraft, an Airbus A330-300, was carrying 283 customers and 13 crew members. Delta said it is working to rebook passengers on alternative flights to complete their trips to Boston.

The Federal Aviation Administration says cabin air quality on commercial aircraft “is as good as or better than the air found in offices and homes.” The agency notes that mechanical failures, such as issues with an engine oil seal or recirculation fan bearings, can occasionally allow fumes into the cabin. Airlines are required to report such incidents to the FAA, which investigates the cause before an aircraft returns to service.

Aircraft are also required to meet minimum ventilation standards, providing the equivalent of 0.55 pounds of fresh air per minute per occupant, a rate the FAA says is consistent with other public indoor environments.

The Porto diversion follows a string of similar in-flight disruptions this year. Earlier in 2025, a Cape Air flight bound for Boston returned to Nantucket shortly after takeoff when the upper section of its cabin door partially opened mid-flight. And on Aug. 31, a Delta flight from Minneapolis-St. Paul to Orlando turned back minutes after departure due to a reported medical issue involving a pilot; that flight, carrying 178 passengers and seven crew members, landed safely and continued on with a new crew.