Water vapour filled the cabin of a Spring Airlines flight bound for Shanghai before takeoff at Don Mueang International Airport on April 12.

However, Spring Airlines quickly responded to the incident and clarified that what passengers saw as "smoke" was actually water vapour generated by the air conditioning system.

According to the airline, the cooling and drying process of the air conditioning system results in a significant amount of condensation when entering hot and humid air, leading to a misty appearance that can be mistaken for smoke.

It is a common physical phenomenon in aviation known as "cold air turbulence," where temperature differences between the inside and outside of the cabin can cause water vapour to condense into visible clouds.

Aviation professionals further explain that this is a routine occurrence that poses no danger to passengers or the aircraft. As the cabin temperature is lowered, the moisture in the air is released and quickly dissipates, leaving no residue or lasting effects.

The video was provided by a passenger named Du.

4月12日，曼谷廊曼机场，游客杜女士乘坐春秋航空的航班从曼谷飞往上海，飞机起飞前机舱内出现了烟雾缭绕的一幕。对此，春秋航空回应称，机舱内出现的是水汽, 系空调打出的冷却干燥空气，进入高温潮湿空气时产生大量冷凝气。航空专业人士称，这是一种物理现象，内外冷热不均，客舱释放冷气就会如此。视频由杜女士提供。