"The man and woman never did settle in, and as Flight 462 began to taxi out to a runway, the man stood up, ignoring a flight attendant’s order to sit, saying that he had post-traumatic stress disorder..."

"A short time later... the plane shudder[ed] to a stop.... The man had forced open a cabin door, activating an emergency slide, and then he, his female companion and their [large service] dog slid their way out of the plane, officials said.... This was not the first time a panicky passenger has pulled such a maneuver at a New York-area airport, but neither Delta, the F.A.A. nor the Port Authority of New York and New Jersey, which operates La Guardia, could say on Monday just how unusual it was for someone to make such an escape... [R]ecently, a traveler aboard a Florida-bound flight at Newark Liberty International Airport fled through an emergency exit and down an inflatable slide while the plane was still at the gate in February 2018....  yelling that he did not belong on the plane because it was not his flight...."

From "2 Passengers and a Dog Slide Out of Moving Plane at La Guardia/Delta Flight 462 was delayed for hours after a male passenger forced open a cabin door while the plane was taxiing. He and his companions slid their way out of the plane" (NYT).

ADDED: These cases seem ridiculous, but claustrophobia is a real anxiety disorder. Wikipedia says: "Being enclosed or thinking about being enclosed in a confined space can trigger fears of not being able to breathe properly, and running out of oxygen.... Most claustrophobic people who find themselves in a room without windows consciously know that they aren't in danger, yet these same people will be afraid, possibly terrified to the point of incapacitation, and many do not know why." It says here that 5 to 10% of people have severe claustrophobia, so the wonder is that it is so rare to see anyone panicking on a plane. Perhaps every plane has passengers who are experiencing panic but — "terrified to the point of incapacitation" — nothing shows on the outside and taking action — like opening the emergency slide — is not an option.