A man who was found guilty of sending a menacing "tweet" challenges his conviction at the High Court on Wednesday.
Paul Chambers, 27, has brought judicial review proceedings after his appeal against conviction and sentence was dismissed by a judge at Doncaster Crown Court in October 2010.
Chambers had argued that no-one would ever have taken seriously his threat to blow an airport "sky high".
The message read: "Crap! Robin Hood Airport is closed. You've got a week and a bit to get your shit together, otherwise I'm blowing the airport sky high!'
But, Judge Jacqueline Davies, sitting with two magistrates, said the electronic communication was "clearly menacing" and that airport staff were sufficiently concerned to report it.
She added: "We find it impossible to accept that anyone living in this country, in the current climate of terrorist threats, would not be aware of the consequences of their actions in making such a statement."
Accountant Chambers, who was ordered to pay a £385 fine, claimed he sent the tweet to his 600 "followers" in a moment of frustration after Robin Hood Airport in South Yorkshire was closed by snow in January 2010.