Where We've Been; Where We're Going

In the early days of the pandemic I posted quite a few articles which – from feedback received – were helpful to pilots. Then I stopped, as the information became more widely known – reasoning that yet one more source of information repeating the same thing wasn’t helpful. Now, at the roughly 6 month stage, enough has changed and new things come to light that another update would be, in my opinion, helpful.

I enjoy discussing this with pilots because we speak parallel languages. You “get” some of the key concepts. Firstly – how have we done so far? Lots of people – including some pilots, are looking at the economic devastation caused by this thing and asking whether we over-reacted. Just as good safety is boring (nothing happens) so is good public health. We did not have “bodies stacked like cordwood” as one helpful article from the Herald suggested was a possibility, hospitals were largely quiet, ICUs were not overwhelmed and funeral homes did not need refrigerated trailers to hold the dead. These things have all happened in other jurisdictions (looking at you America) that did not manage as well. We have gingerly come out of lockdown with increasing numbers – as we knew we would have, but so far no catastrophic surges. Should it have ever got to this? Clearly no – the world was caught flat-footed and the response has been uncoordinated and in some cases – chaotic. But by and large society has responded well. Our industry is devastated, and will be until Covid is brought under control – hopefully through vaccination/herd immunity. Until then, we manage risk.

For an overview- This is a great review article by one of my favourite lay-authors, Ed Yong: How the Pandemic Defeated America. It is well worth reading.

Secondly – as every pilot knows – safety rules are written in blood. They flow from new lessons learned – often as a result of accidents, or getting it wrong. Any “living” endeavour will have change as its constant – we see that in aviation – and certainly in medicine. We learn new things. The advice we gave yesterday may prove to be wrong – or at least incomplete. So advice should change – and is changing – including mine. So what have we learned – and how does that change things?

New Learnings about Corona virus

This is not intended to be an exhaustive literature review but more of a “bullet-point” set of facts that are relevant and new(ish).

Firstly, we didn’t understand just how prevalent asymptomatic spreading is. Studies coming out over the past months point to a significant percentage of Covid positive patients having no symptoms, and yet shedding as much of a viral load as ill individuals (they may even shed more/longer). This is highly unusual – and completely different from other epidemic diseases like Ebola. (source

Hence, screening methods that rely on asking people about symptoms – or measuring their temperatures – will miss a significant minority of infected individuals. Unfortunately, such individuals seem to be over-represented in “super-spreader” events – where one positive case causes 40 or 50 infections in a brief time frame. This means everyone has to adopt preventative measures to stop spread – which are masks and hand washing.


When this first hit, many of us, admittedly including me, didn’t understand that this virus doesn’t spread as an isolated particle – but enveloped in moisture from someone’s breath. Cloth or regular paper masks are ineffective at stopping something as small as a virus – I likened it to putting a chain link fence in front of an open hangar door and trying to stop mosquitoes – won’t work. But what if every mosquito was inside a baseball? Now you’d have a pretty good defence – and it turns out that’s what we’re dealing with – viral particles spread inside of respiratory moisture. What if the mask wasn’t so much to protect the wearer – but everybody else? Turns out it does both.

So once we understand that, what can science tells us about cloth masks? Using a fan blowing aerosol particles at typical resting breathing rate, the scientists measured the number and size of particles in the air before and after it passed through each mask. Those made with a combination of fabrics — one tightly woven cotton sheet with two layers of chiffon (90 per cent polyester and 10 per cent spandex) — filtered out 80 to 99 per cent of aerosol particles, making them nearly as effective as an N95 mask.

Substituting chiffon with natural silk or flannel produced similar results, as did a cotton quilt with cotton-polyester batting. Researchers also report that high-thread count fabrics (like cotton) act as a mechanical barrier to aerosols, while fabrics that hold a static charge (like some chiffon and silks) can serve as an electrostatic barrier.

Fit is key too. Even a one-per-cent gap in the mask reduced the filtering efficiency of all masks by 60 per cent or more. It’s important to wash masks after every use to avoid cross-contamination, as well, so having more than one is useful. (source

Does it work in real life? “No cases of coronavirus have been linked to two Missouri hairstylists who saw 140 clients last month while symptomatic, county health officials said. Both stylists worked at the same Great Clips location in Springfield. The clients and the stylists all wore face coverings, and the salon had set up other measures such as social distancing of chairs and staggered appointments, the Springfield-Greene County Health Department said this week.

Of the 140 clients and seven co-workers potentially exposed, 46 took tests that came back negative. All the others were quarantined for the duration of the coronavirus incubation period. The 14-day incubation period has now passed with no coronavirus cases linked to the salon beyond the two stylists, county health officials said.

During the quarantine, those who did not get tested got a call twice a day from health officials asking whether they had symptoms related to Covid-19, said Kathryn Wall, a spokeswoman for the Springfield-Green County Health Department. “This is exciting news about the value of masking to prevent Covid-19,” said Clay Goddard, the county’s director of health.” (source

Airborne spread:

Much confusion reigns about this topic. WHO insists Covid is not airborne – then back-tracked to qualify that statement. Terminology around “droplets” and “aerosols” confused the public. For a good examination of the topic in a highly readable article, look at this:

Several well documented “super-spreader” events feature heavily in these analyses. To recap here:

“In another super-spreader event, at a choir practice of 61 people in Skagit, Washington, a single patient caused 32 confirmed and 20 likely COVID-19 cases—almost everyone in the room. In another striking case, at a Korean call center, where people talk all day, 94 out of 216 people on one floor of the building were infected, with cases clustered on one side of the floor but some as far as 20 desks away from each other, with a few as far away as the opposite wall. Only three people on other floors were infected, despite the employees sharing a lobby and elevators, reinforcing that surfaces aren’t efficient transmitters, but that shared air pockets can be, almost regardless of distance.

For these super-spreader events, Milton says you have to “really jump through hoops to argue that they were anything other than transmitted by air.” But it’s not only COVID-19’s super-spreader events that are indoors. The rest of the pattern of spread of COVID-19 —when it is spreading slowly, in small numbers—is also overwhelmingly through indoor transmission. Milton told me that if those sprayed droplets were the primary means of transmission, we would expect to see more transmission outdoors, since the droplets are being ejected with some force and falling on people, but that doesn’t seem to be the case. Even if sunlight, which can deactivate viruses, were dampening transmission outdoors, one would at least expect to see a lot more outdoor transmission than we are seeing now. Instead, epidemiologists are finding that this disease stalks us indoors.” This quote is from an excellent Atlantic magazine piece. Read it for a much fuller explanation of droplet size and airborne spread: source

So while the traditional epidemiology definition of “airborne” (spreading throughout whole buildings, spreading via HVAC systems, Ro of 9-12 or more, like measles) may not be accurate – this virus appears to hang in the air from human speech – especially shouting or singing – and can infect many minutes later. It can be carried some distance by air conditioning airstreams within a room – and stagnant indoor air appears to be the worst. So it turns out most, but not all, risk can be eliminated by staying 6 feet apart.

In a fascinating paper, some researchers use Schlieren photography to actually image human breath spread during talking – these need to be watched by everyone discussing masking: Imaging human exhalation

Especially watch video S4

Also here:

Contrastingly, touching surfaces really doesn’t seem to be the huge issue we thought it was at the start. This has led to questioning as to why we are expending so much effort on disinfecting surfaces while largely ignoring air filtration and air movement. Read this for a discussion: Don’t get me wrong – this virus loves plastic – and can survive for up to 3 days there – so hand washing and sanitizing are still important – but airborne mitigation is much more so.

Which brings us to our main topic : Is airline travel safe (is going to sim safe)?

I have had many discussions with pilots over this issue. Cutting to the chase the answer is “basically yes” – provided you strictly adhere to safety protocols – which pilots excel at. Firstly – as the discussion above intimates, stay out of environments where the air is still, and unrefreshed. Outdoors is best, followed by well ventilated indoor areas – or airline cabins - where air exchange is good and HEPA filtered. Mask always – preferably N95 if you can find them – if not – cotton works fine. Hand washing is best, sanitize if you can’t wash, and never touch your eyes, mouth or nose without washing/sanitizing first. If you don’t have to eat/drink in a public place – don’t. Go straight to sim – otherwise stay in your room and do not socialize. You are there to do a job – do it and get out. Assume everyone around you is potentially a source of infection – just as you assume everyone around you on the road is an idiot and out to kill you, driving defensively as a result. Before entering into long conversations with people – particularly strangers, ask yourself is this conversation really necessary? Even with masks, is it necessary to sit within 3 feet of someone discussing conversational topics – and potentially exchanging breath aerosol? I respectfully suggest it isn’t. Bottom line – be antisocial.

Social distancing works – do it whenever possible. Onboard you can’t.

How about as a passenger? I continue to fly as one during the pandemic, showing you I’m putting my money where my mouth is. I do all the things previously mentioned.

So what can airlines be doing (better)? Some of these suggestions will certainly fall on deaf ears – but here they are anyways. Ban carry-on except for purses/briefcases. A recent flight saw people racing down the aisle – many rows from their actual seats – to stow overhead baggage. As they did, they stood over top of seated pax – and if their nose poked over the mask top (as it did distressingly often) – they are directing jets of potentially infected breath down onto fellow passengers. This is idiotic.

Masks from the moment one enters an airport to the moment one leaves at destination are mandatory – and no, wearing one over your chin doesn’t count. This is simply non-negotiable. We demonstrate how to put on a seat belt – (repeatedly!) – something your average 3 year old has mastered – we obviously need to demonstrate how to wear a mask.

Stop all meal service. It is not necessary to eat or drink on board an aircraft – period. We live in a society that seems to think going 30 minutes without stuffing something into our mouths will result in death or dehydration. It won’t. Don’t ban food or drink brought on board by those who feel they need it, but don’t provide it if they don’t have it.

Keep ventilation going as an urgent priority. Still air is our enemy. APU/air units on the ground, open vents in the air.

Airlines appear to be doing a good job of disinfecting cabins – keep it up. But don’t get sucked into the “hygiene theatre” mode in similar fashion as security removing nail scissors. Disinfecting alone won’t get us there.

From what I’ve seen, social distancing during boarding, masking and actual boarding procedures are all good – and getting smoother. Keep it up. Maintain employee discipline – passengers look to airline employees for cues as to how seriously to take the requests, and unmasked CSAs having a lengthy social conversation in front of them is highly unhelpful.

This is a pretty good article which reinforces the foregoing points:

Hang in there! Better days ahead…..

Back to News