Clayton Osbon, 49, who recently underwent a court-ordered psychiatric exam, faces a federal charge of interfering with a flight crew.
Osbon "is able to understand the nature and consequences of the proceedings against him" and capable of assisting his attorney, the judge ruled.
"The defendant is not suffering from a mental disease or defect which would interfere with his ability to meet the legal criteria of competency to stand trial," the ruling states.
Court documents indicate an insanity defense is planned. The psychiatric evaluation was sealed Friday.
The case stems from a bizarre incident during a March 27 flight from New York to Las Vegas.
After rambling about religion in the cockpit, Osbon, of Richmond Hills, Ga., told air traffic controllers to be quiet, turned off the plane's radios and dimmed his monitors, court documents state.
"We're not going to Vegas," he told the first officer, according to the affidavit.
Osbon then ran through the cabin and was locked out of the cockpit.
He wound up being restrained by passengers until the plane made an emergency landing in Amarillo.
On Wednesday, a group of 10 Flight 191 passengers -- most from Long Island -- sued JetBlue, alleging the airline knew or should have known that Osbon was unfit to fly.
Steven Epstein, of Garden City, one of the plaintiffs' attorneys, said the finding that Osbon is competent to stand trial doesn't weaken the lawsuit.
"There's a big difference between a competency hearing and an insanity defense," Epstein said. "This just means that the [criminal] case can proceed."
A JetBlue spokeswoman declined to comment on the lawsuit.
Osbon, who had flown for JetBlue since 2000, faces up to 20 years in prison and a $250,000 fine if convicted.