Flight disruptions caused by troubled passengers have risen worldwide in recent years. A Thai Airways flight was recently delayed following a passenger opening the aircraft's emergency exit door, deploying the emergency slide as the plane was taxiing for departure.

Unexpected Deployment

Thai Airways Flight TG121 is a regularly scheduled domestic flight from Chiang Mai (CNX) to Bangkok Suvarnabhumi (BKK). The flight takes one hour and is usually operated by the Airbus A320. On February 7, Flight 121 was taxiing for takeoff in Chiang Mai for departure. The aircraft operating was HS-TXC, an 11-year-old Airbus A320-200.

Around 10:05 p.m. local time, Chiang Mai International Airport's Control Tower was notified that the A320's L1 exit door had been opened, deploying the emergency slide. At this point, the aircraft had turned onto Runway 36 and was awaiting takeoff clearance.

Wong Sai Heung, a 40-year-old Canadian national, had reportedly suffered a panic attack and rushed to the front of the plane in an attempt to escape. Another passenger and flight attendant subdued Heung as he allegedly claimed that someone was about to attack him. The aircraft could not be moved immediately due to the deployment of the A320's slide. As such, Thai Airways mechanics had to be dispatched to cut the slide before moving the plane.

Wing Commander Ronnakorn Chalermsanyakorn, director of Chiang Mai International Airport, said regarding the sudden incident:

"After receiving the alert [about TG-121], we reached out to Thai Airways mechanics to get into the site cut the evacuation slide off, then we towed the aircraft back to landing pit [gate] number 15." 

Delays and Arrest

Chiang Mai Airport only has one runway, RWY 18/36. Because the afflicted A320 could not be moved immediately, this caused various flight disruptions. Wing Commander Chalermsanyakorn added that 13 flights were affected by the incident, beyond departures. Eight flights were forced to enter holding patterns until the A320 was towed off the runway.

Chiang Mai Airport's runway was reopened around 10:50 p.m. In total, 2,295 passengers were affected by this unexpected delay. According to a statement by Thai Airways, mechanics were able to repair and inspect the L1 exit door of the A320. The aircraft was re-boarded and departed for Bangkok just after 12:30 a.m. local time, running three and a half hours late.

Mr. Heung, who opened the door, was arrested by Chiang Mai Police. The authorities said they were unaware of Mr. Heung's motive for opening the door. However, the individual appeared stressed and was difficult to communicate with. As such, Colonel Manuschai In-thuean of the Chiang Mai Police noted that Mr. Heung was sent to the Suan Prung Psychiatric Hospital for an evaluation.

Still, Mr. Heung has been charged with endangering an aircraft and its passengers by refusing to obey the captain's orders. Mr. Heung's bail request has been denied. He recently appeared in the Chiang Mai Provincial Court. If found guilty, he could face imprisonment for up to 20 years or a fine. This fine amounts to around 600,000 to 800,000 Thai baht ($16,700-22,300).

Mr. Heung could also face the death penalty. However, Thailand has not carried out a prisoner execution since 2018. It is also important to remember that Mr. Heung is a Canadian citizen. Thailand's Canadian embassy has been contacted about the incident, and what will follow remains to be seen.