A flight from Luton Airport to Majorca was delayed as police inspected an aircraft after cabin crew found a "scribbled note" on board.
The crew were preparing the plane when they found the note
The note was found on the back of a safety card as cabin crew prepared the plane for a 1430 BST take-off.
The aircraft was cordoned off as police went on board to inspect the plane.
The scare comes during a heightened state of alert at UK airports following an alleged bomb plot to blow up several transatlantic airliners.
A spokeswoman said that passengers, who had been kept in the terminal building during the scare, had boarded the flight at 1530 BST.
It had not caused any disruption to flights at the airport, she added.
On Friday, a charter flight from London to Egypt was diverted for security checks after a note claiming there was a bomb on the plane was found scribbled on a sick bag.