Lauda Air Flight 004 was a scheduled passenger flight operated by Lauda Air, a charter airline based in Austria. On May 26, 1991, the Boeing 767-300ER took off from Bangkok, Thailand, bound for Vienna, Austria. Shortly after takeoff, while cruising at high altitude, the aircraft suddenly broke apart mid-air and crashed into the rugged terrain of Phu Toei National Park in Suphan Buri Province. Tragically, all 223 individuals on board, including 213 passengers and 10 crew members, lost their lives in the incident.

The investigation into the crash was led by the Thai Transport Ministry and involved various international aviation authorities. It was determined that the primary cause of the crash was the uncommanded deployment of the thrust reversers. This malfunction occurred during the aircraft's climb, leading to a rapid loss of control. Following the accident, Lauda Air faced significant scrutiny, and their fleet underwent extensive inspections and improvements in safety protocols. The findings resulted in crucial changes in regulations and oversight within the aviation industry regarding the design and functioning of thrust reversers.

The public reaction was immense, as many were shocked by the sudden loss of life and the technical failure of a modern aircraft. The incident highlighted the vulnerabilities within aviation technology, leading to debates about safety measures and maintenance standards in the airline industry. The tragedy led to advances in pilot training and emergency protocols designed to prevent future disasters of this nature.