A plane carrying 185 passengers was diverted to Dublin Airport when crew reported feeling "nauseous and dizzy".
The US Airways jet flying from Venice to Philadelphia landing safely in Dublin at 3.15pm on Saturday.
According to the BBC, paramedics were waiting for the flight when it landed and nine people were taken to Beaumont Hospital in Dublin for observation.
Sky News reports that US Airways spokeswoman Michelle Mohr said in a statement: "Medical professionals are evaluating our flight attendants and we are re-accommodating our customers on other flights to Philadelphia."
In 2012, a passenger was hailed a hero after taking over the controls of a plane and helping it land at Dublin Airport when the first officer fell ill.
The German man, an off-duty pilot, offered his services when the cabin crew announced the plane, carrying 264 passengers, was being diverted to Dublin.
He asked a member of staff the reason for the diversion, and found out the first officer of the Lufthansa Boeing 747 had been taken ill while flying over the Atlantic.
The off-duty pilot had been travelling as a passenger on a Lufthansa 747 flying from Newark to Frankfurt when the crew member suffered a severe migraine and was incapacitated.
A source involved in the incident told the Independent.ie: "It was a miracle. It had all the elements of a Hollywood movie but thankfully one with a happy ending."
The man highlighted the fact he was a qualified pilot, and helped the plane safely complete an emergency landing in Dublin at around 6am.