Mohammad Farooq, 28, had a pressure cooker device designed to be twice as explosive as those used by the Boston Marathon bombers in 2013.
Armed police arrested him at St James’s Hospital, Leeds, in January last year after patient Nathan Newby talked him out of his attack, taking him outside.
Farooq, who told him he wanted to “kill as many nurses as possible”, also had a blank-firing gun, which Mr Newby persuaded him to put down.
The extremist worked at the hospital as a support worker and had a grievance against colleagues.
But his primary reason for the plot was that he had become radicalised by online extremist Islamist ideology which encouraged lone wolf attacks.
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His initial target was RAF Menwith Hill, North Yorks, but he found it too difficult to attack.
Farooq, of Leeds, admitted having an explosive substance with intent and a firearms charge.
He denied preparing terrorist acts but yesterday a Sheffield crown court jury found him guilty.
He will be sentenced later.
Bethan David, from the Crown Prosecution Service, said: “Farooq is an extremely dangerous individual.
“The extremist views he holds are a threat to our society and I am pleased the jury found him guilty.”