Brian Plummer was sitting in the back of a Delta Air Lines flight preparing to leave LaGuardia airport on Monday, when he noticed a man and woman near a large service dog.

Mr. Plummer said the plane to Atlanta was not completely full, and the couple changed seats several times.

Mr. Plummer said the man and woman were never settled, and when Flight 462 began by taxi to the runway, the man stood ignoring the flight attendant’s order to sit down, saying he was suffering from PTSD.

Mr. Plummer said that soon after the plane had stopped he felt the plane stopped. It was not immediately clear to him why, but the cabin crew eventually told the passengers what had happened.

Officials said the man had forcibly opened the cabin door, activated the emergency chip, and then he, his companion and their dog slid out of the plane.

Spouses were in custody; It was not clear what charges, if any, they might face, or whether they might be prevented from traveling with Delta in the future.

It wasn’t the first time a frightened traveler had pulled such a maneuver at an airport in the New York area, but neither Delta, nor the Federal Aviation Administration, nor the Port Authority of New York and New Jersey, which runs LaGuardia, could say on Monday how unusual it is for someone to do With such an escape.

“It doesn’t happen every day at the airport,” said authority spokeswoman Lennes Valens.

Mr. Plummer said he noticed the man standing after the plane left the gate. “They looked really cool,” Mr. Plummer said of the couple.

Mr. Plummer said the man told a flight attendant he could not sit due to PTSD.

“If I sit down, I will panic,” Mr. Plummer recalls.

Mr Plummer said that the stewardess asked the man again to sit in his seat, and he refused again. Instead, he started walking toward the nose of the plane, far enough away that Mister Plummer lost his sight.

A Delta spokeswoman said that the plane, which was scheduled to leave shortly before ten o’clock in the morning, returned to the gate, where “the remaining passengers landed normally and were accommodated on alternate flights.” (Mr. Plummer said his departure was delayed by several hours.)

The authorities said that no one was injured in the accident. It was not immediately clear where the service dog was.

The most famous example of an unauthorized slide exit that occurred 10 years ago at Kennedy International Airport, B. JetBlue flight attendant Who said he was involved in a dispute with a passenger.

In that case, after announcing his intentions for the plane’s public address system, the flight attendant activated the emergency chip, slipped onto the runway and threw his tie on the ground as he walked away.

Recently, a passenger on a Florida-bound flight escaped at Newark Liberty International Airport via the emergency exit and down an inflatable slide while the plane was still at the gate in February 2018. According to WNBC.

The TV station reported that when the officers arrived to arrest him, the man was shouting that he did not belong to the plane because it was not his flight.