Air-Conditioning Vents Pump Fog Into Airplane Cabin During Flight From Bali to Adelaide

Storyful Published February 19, 2019 733 Plays

Rumble / Airplane IncidentsHave you ever seen this strange fog in the airplane cabin during your flight?
It is formed by the air conditioner and often happens during the humid temperature outside the airplane with cooler air in the cabin. It is nothing to worry about. This video, from a February 5 flight from Bali to Adelaide, shows a thick fog being injected into the airplane cabin.

Pilots are well used to fog causing delays to land and takeoff, but it is not every day that the fog is actually inside the plane during the flight.

Hot and humid outside air rapidly condensing upon contact with the aircraft’s onboard air conditioning unit that creates billows of steam. In this specific instance, there is so much steam because the air conditioning is blasting, and steam is the result of all that hot and humid air mixing with air that is much cooler.

An aircraft cabin is so dry that it absorbs moisture from anywhere it can, including human skin. The air inside the cabin of an airplane typically has a humidity level of 10 to 25 percent, much lower than a comfortable typical indoor humidity of 30 to 60 percent.

when aircraft take off, the air pressure in the cabin decreases. Cool conditioned air inside the plane mixing with hot humid air outside from the plane and the mist begins to form. The temperature of the air also reduce and if it is rapid enough the air will cold enough for the water in the air to condense immediately, forming the fog that the passengers witnessed.

Although the fog was not considered a safety concern, some passengers were naturally a little concerned. As a result, the captain waived a $7 charge for alcoholic drinks, helping to calm some nerves along the way! According to Boeing's report, published in 1999 aero journal, load factors, high seating density, and airplane utilization rates can cause increased cabin humidity and therefore greater condensation rates.

Aircraft cabins are pressurized using cooled and filtered air bled from the engines, keeping the air pressure inside the cabin at the equivalent of an altitude of 8,000ft, even though commercial airplanes often fly at 45,000 ft. Technical problems with the pressurization system are one cause, but cracks in windows or the fuselage, incorrectly sealed doors, and breaches in the aircraft are also all potential triggers, allowing cabin air to escape.

Will fog in the cabin damage the aircraft?

The short answer is "yes and no." Stefan Jacob, sales director of aviation for Mickiewicz, says interiors coatings and undercoat combinations are tested for moisture buildup of any kind: "The results of these experiments show that the painted surfaces enduring fulfill the qualitative demands defined in the prescription, and undercoats or substrates will be sustainably protected." Coatings, such as the Alexis-FST from Mickiewicz, provide more benefits to surfaces than meets the eye. However, moisture increase is potentially hazardous for the interior wall of the airplane if it is not addressed precisely.

A simple rule of thumb: if you board an airplane filled with steam, and the cabin crew and pilots are conducting business as usual, it’s a pretty safe bet it is not toxic smoke that is filling the cabin.