Testing the Feasibility of Operating a Helicopter While Wearing Different Masks

Dear Editors:

Emergency medical service agencies at all levels have spent the last year dealing with dramatic changes as a result of the coronavirus disease 2019 (COVID-19) pandemic. Air medical transport has been no exception.¹ Services have instituted various measures to ensure patients and crews are well protected from in-flight exposures, such as wearing personal protective equipment (PPE).² An overwhelming body of evidence suggests that masks and various degrees of PPE can acceptably reduce the risk of contracting COVID-19. Furthermore, all PPE is not created equal; specific types of masks seem to offer more protective effects.³ Anecdotally, some health care providers and pilots have reported masks contributing to fogged eyeglasses and a reduced ability to perform various job-related tasks; for air medical flight crews, excessively fogged eyeglasses or a reduced ability to perform job-related tasks could be a significant safety concern. There is not much literature on how wearing infection control PPE affects an individual's ability to operate an aircraft.

To understand how wearing various types of masks affects an individual's ability to operate a helicopter, I attempted to fly a helicopter while wearing 5 different types of masks: a cloth mask, a surgical mask, a KN95 mask, an N95 mask, and an elastomeric mask (Figure 1 ). I specifically wanted to identify if these masks led to fogged eyeglasses or hindered my ability to operate the aircraft. An unmasked pilot was seated next to me and could intervene if necessary.

Figure 1.

Aditya Shekhar, pilot and author, testing the feasibility of operating a helicopter while wearing different masks.

I was able to maintain control of the helicopter while wearing all types of masks. However, in my testing, specific advantages and disadvantages with the various types of masks became apparent (Table 1). None of the masks appreciably hampered my field of vision, but all masks slightly reduced my ability to communicate through the headset to varying degrees. The elastomeric mask (3M, St. Paul, MN) I tested rendered my headset unusable; even while shouting, the microphone was only able to register parts of sentences, and I was not able to safely communicate. With the other masks, I was able to position the microphone receiver close enough for it to register my voice; this allowed me to easily communicate with others in the helicopter and air traffic control. In general, I found masks that wrapped around my head, as opposed to around the ears, felt most secure and comfortable during long intervals and interfered the least with my headset. All masks did increase the incidence of glasses fogging to varying degrees. Placing my glasses over the nose bridge of the mask did reduce this effect, and I found a well-fitted N95 mask and an elastomeric mask were the most effective at reducing fogging, most likely because of the tight fit of the mask regulating the flow of moisture. KN95 masks were slightly less effective, whereas cloth masks and surgical masks allowed air to seep over my glasses. Temperature also seemed to affect my glasses’ propensity to fog; on colder lenses, warm exhaled air was more likely to condense. Of course, this test is far from exhaustive; rather, I wanted to open a dialogue about how individual pilots and air medical services are approaching infection control among flight crewmembers and ensuring the safe operation of both rotor wing and fixed wing air ambulances.

Mask Type	Benefits	Disadvantages
Surgical mask	Relatively cost-effective Relatively easy to obtain Does not require fitting	Contributes to glasses fogging Comparatively low level of COVID transmission prevention
Cloth mask	Relatively cost-effective Relatively easy to obtain Reusable Does not require fitting	Contributes to glasses fogging Comparatively low level of COVID transmission prevention
KN95 mask	Reduced glass fogging compared with cloth and surgical masks Could be more effective than cloth and surgical masks	Contributes to some glasses fogging Expensive and hard to procure
N95 mask	Considered highly effective against COVID transmission Wraps around the head instead of the ears Reusable	Puts pressure on the nose, which could be uncomfortable during long periods of time Expensive and hard to procure Requires fitting
Elastomeric mask	Considered extremely effective against COVID transmission Highly reusable	Most expensive and hard to procure Might prevent adequate use of headset Requires fitting