Jet2 is seeking to establish why one of its flights was shadowed by a French air force fighter aircraft.
Passengers flying from Spain to Birmingham witnessed the fighter jet from France.
It tracked the passenger aircraft from Malaga for up to 15 minutes.
A passenger from the West Midlands, said: “It was so close I could read the writing on its tail fin.”
The passenger – who was travelling with her husband and their 13-year-old daughter said: “Someone spotted the French jet and told the cabin crew, who I presume told the Jet2 pilots.
“The air stewardess then announced there was nothing to worry about.
“My husband was terrified and it didn’t help that loads of other passengers came by us to look out at it.”
The family photographed the aircraft seemingly tracking Flight LS1204 and said the feeling on board was “a mixture of excitement at seeing the fighter so close up and terror as to if we were about to get shot down”.
A Jet2 spokesman said: “We are awaiting clarification from the French air traffic authorities, as to why a military aircraft was apparently tracking our aircraft.”