To convince the public that airplanes are safe during the ongoing pandemic and rekindle demand for air travel, airlines are instituting innovative and elaborate procedures to keep airport and airplane surfaces and high-traffic areas clean and disinfected. Now the U.S. Federal Aviation Administration (FAA) warns that the effects of some cleaning procedures on aircraft interiors and equipment might pose risks to flight safety.
The Sterile Cockpit
The Sterile Cockpit refers to a FAA regulation requiring that during critical phases of flight – normally below 10,000 feet – pilots must limit activities on the flight deck to those required for the safe operation of the aircraft. The regulation applies to U.S.-based airlines, regional air carriers, and cargo operators that operate scheduled or charter air service. The FAA adopted the rule in 1981 after finding that mistakes by flight crews who were distracted from their flying duties by non-essential conversations or activities during the approach or departure phases of flight was the cause of or a contributing factor to several accidents.
In the age of the novel coronavirus, the term “sterile cockpit” is taking on new meaning.
Aircraft Cleaning Poses Its Own Risks
The best defense against onboard transmission of SARS-CoV-2, the novel coronavirus that causes the disease known as COVID-19 disease, are HEPA air filters that come installed on all mainline aircraft. These surgery-suite grade filters completely recycle cabin air every two to three minutes and remove at least 99.97% of dust, pollen, mold, bacteria, and airborne virus particles with a size of 0.3 microns or larger.
Airlines are going further and disinfecting cabins daily or between every flight. Some are deploying fogging techniques or electrostatic spraying with highly effective, EPA-registered disinfectants rated to combat many communicable diseases.
But on November 4, 2020, the FAA issued an Airworthiness Directive stating that ” although the Environmental Protection Agency publishes a list of disinfectants effective at inactivating COVID-19, the majority of the products listed may not be suitable for use on aircraft, except in very limited and localized application.” The concern is the potential effect on sensitive equipment, wiring, and other components.
So how can airlines sanitize areas on a plane where disinfectants might cause harm to sensitive equipment? Ultraviolet light is one option.
Ultraviolet Light Is Powerful Enough To Kill Viruses
Ultraviolet (UV) light is electromagnetic radiation emitted at wavelengths that are shorter than the violet end of the visible spectrum (visible light) but longer than X-rays. UV light is divided into three zones—UV-A with wavelengths between 380 to 320 nm (billionth of a metre), UV-B wavelengths between 320 nm to 290 nm, and UV-C wavelengths between 290 nm to .1 nm.
All types of UV radiation are components of sunlight. In addition to sun tans, UV-A and UV-B cause sunburns and skin aging. Long-term exposure to this radiation is associated with skin cancer. Artificial UV-A light is used for tanning beds and blacklight lamps.
UV-C is the most energetic and harmful type of UV radiation. Fortunately for life on Earth, the ozone layer in the stratosphere absorbs UV-C and most UV-B radiation before it reaches the surface.
UV-C light kills SARS-CoV-2 because it destroys the genetic material — DNA or RNA — of viruses and bacteria.
UV-C has been used as a disinfectant in wastewater and air filtration systems for many years. It is also used to sterilize instruments in commercial settings like hospitals and spas.
UV-C Is Ideal For Areas Sensitive To Chemicals And Liquids
At least one airline, United Airlines, is using UV-C light to sanitize flight decks.
This 55-second video shows a United employee cleaning a cockpit and instrument panel using a UV-C device.
Using a handheld device like the one in the video can be effective but doesn’t seem like the best way to ensure all surfaces are properly treated. Although it would require constructing new facilities and taking aircraft out of service, the best way to sanitize aircraft with UV-C radiation might be to put the whole plane in a hangar flooded with UV-C light. That should sanitize all areas of the aircraft accessible to passengers and pilots. China does something similar with busses.
Using UV-C drones to fly around inside the cabin is another possibility. That has been tried, but GPS signals have difficulty penetrating the airframe. To avoid the GPS problem, airlines could also try UV-C robots like ones used in hospitals if they haven’t already done so.
Two months ago, I published a post about the use of ultraviolet light C to kill SARS-CoV-2, the novel coronavirus that causes the disease known as COVID-19. I ended up buying a small Mobile Klean UVC device to use during travel to sanitize things like keyboards and keypads, remote controls, seat controls and video screens on airplanes, and other surfaces on airplanes and in hotels.
I haven’t used it because I haven’t traveled. As SARS-CoV-2 infections are spiking in the U.S., I’m considering taking a short domestic trip in the near future. If things keep going this way, quarantines and other restrictions may effectively shut down travel for the next few months. If I do fly, it will be on an airline like Delta or Alaska that blocks middle seats.