Two separate Delta Air Lines flights encountered fumes or unusual odors in the cabin this week, triggering precautionary diversions and emergency procedures.

On Tuesday, Sept. 8, a Delta flight from New York City to Chicago O’Hare detected fumes onboard while en route. The crew declared a mid-air emergency to receive priority from air traffic control and land as quickly as possible.

The aircraft, carrying 130 people including five crew members, landed safely at O’Hare around 4:15 p.m. local time. All passengers deplaned normally at the gate, and Delta removed the aircraft from service for a maintenance inspection.

The previous day, Monday, Sept. 7, another Delta flight experienced an odor while flying from Jacksonville, Florida, to New York City.

The crew of Flight 1035 responded by diverting to Raleigh-Durham International Airport, where the aircraft landed safely. The flight had 113 people aboard, including five crew members. Everyone left the aircraft normally, while Delta assisted affected passengers with alternative flights.

Delta said the cause of the odor in the second incident remained under investigation.

The airline emphasized that smoke, fumes and unusual odors onboard aircraft are rare, but each report is treated seriously. Delta said its FAA-approved safety management system is designed to identify and address safety issues, including those involving cabin fumes and odors.

While neither incident resulted in injuries, the back-to-back events highlight why flight crews are trained to react immediately when unexplained fumes or odors are reported in the cabin.