What Is Happening On This Flight: Fog?

Fog caused by the extreme difference between dew points inside and outside the aircraft cabin looks alarming. Although typically harmless, moisture buildup in an aircraft can eventually damage the interior walls.

On Aug. 4, my friend boarded United Airlines Flight 1864 and sent this video to a few people. At 6 a.m. in Minneapolis, the temperature was 78F, with a dew point of 70F. The fog or mist created inside the cabin is produced from the cooler air and dew point inside equalizing with the extreme humidity outside.

Aircraft Fog

According to Boeing's article "Controlling Nuisance Moisture in Commercial Airplanes," published in the manufacturer's January 1999 Aero magazine, high seating density, load factors and aircraft utilization rates can cause increased cabin humidity and therefore greater condensation rates.  

Will it damage the aircraft?

The short answer is "yes and no."

Stefan Jacob, sales director of aviation for Mankiewicz, says interiors coatings and undercoat combinations are tested for moisture buildup of any kind: "The results of these tests . . . show that the painted surfaces enduringly fulfill the qualitative demands defined in the specifications, and undercoats/substrates will be sustainably protected."

These demands include fire, water and even disease control protection. Coatings, such as the Alexit-FST from Mankiewicz, provide more benefits to surfaces than meets the eye.

However, moisture buildup is potentially hazardous for the interior wall of the aircraft if it is not addressed correctly. Stephen Clark, director of marketing and technology for Immaculate Flight, says, "the danger is not to fixtures such as seats and walls, but rather to internal components behind wall panels. This includes electrical fixtures, insulation blankets (like insulation in your home) and wiring."

Moisture buildup also can be caused by frost or accumulation of passenger respiration. When the moisture drips down the cabin walls or even on passengers, it is important that the water is addressed quickly. Moving forward, moisture-control systems such as insulation blankets and improved airflow systems can minimize the amount of unwanted moisture in the cabin.

Updated: reader Kevin Pinkerman sent this video from his flight on Virgin America 219 from Austin to San Francisco on Aug 19. Pinkerman says the heavy humidity that day came from the same storm system that caused the catastrophic flooding in Louisiana. The humidity was 97% at 7 a.m. that morning.

Have a video or picture of your own flight anomaly? Email me your experience, and we can take a look at how something simple might greatly affect an aircraft.



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