Navigating smoke is a dangerous act for all pilots and with the smoke from the forest fires in southeastern Canada posing a significant hazard to aviators, it is important that pilots know what to do if ever in tricky situations. Knowing how to understand upcoming visibility and smoke forecasts or how to avoid smoke altogether could be crucial when operating an aircraft. However, oftentimes pilots have no option but to fly into the smoke which can be hazardous. To learn more about navigating smoke as an aviator, continue reading.
Smoke can present a hazard to all pilots, but especially those flying under visual flight rules.
Given the dozens of forest fires burning out of control in southeastern Canada, mainly in Quebec and Nova Scotia, I have received many inquiries from my followers about how to deal with smoke from an aviation perspective. First and foremost, smoke can present a hazard to all pilots, but especially those flying under VFR.
Smoke lowers visibility, not only at the surface, but aloft as well. It is not unusual for smoke to lower flight and surface visibility to less than 1 statute mile, making flying VFR impossible and dangerous, especially at night and in mountainous terrain. Even under IFR, visibility may be in the low IFR flight category and below published minimums for some airports. In fact, the FAA implemented a ground stop for flights bound for New York’s LaGuardia airport because of smoke and reduced visibility on Wednesday.
So, what’s a pilot to do? If you don’t have to fly, that’s likely the best option. If you do decide to make the flight, it’s best to be on an instrument flight plan. Also, if you have oxygen on board, consider using it even below 10,000 feet. In fact, wearing an oxygen mask is always a good approach.
All smoke contains some carbon monoxide, carbon dioxide, and other particulate matter. Hemoglobin bonds with carbon monoxide 200 times more readily than it bonds with oxygen, and often produces hypemic hypoxia. Depending on what is actually burning at the surface, smoke can contain a variety of different chemicals, including aldehydes, acid gasses, sulfur dioxide, nitrogen oxides, polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, styrene, metals, and dioxins. None of these are good to breathe, especially if you have health issues (also consider your passenger’s health).
The smoke starts as eddies in the planetary boundary layer (PBL). This is the layer of air that is directly influenced by the earth’s surface. But then some of that air gets mixed above the PBL into the free atmosphere, and encounters stronger horizontal winds. Smoke from these fires can travel thousands of miles. In fact, some of the smoke from the Canadian fires has reached as far south as the Carolinas and northern Georgia, albeit in low concentrations of particles.
In the early morning hours, the atmosphere around the regions where the fires are burning is often fairly stable near the surface. That will trap some of the smoke, keeping it close to the surface. The fires burn so hot that they often produce convective updrafts along with “clouds” called pyrocumulus, pyrocumulus congestus flammagenitus, and cumulonimbus flammagenitus (with lightning) that carry the smoke high into the flight levels. These “clouds” don’t produce any rain, but those updrafts can contain severe turbulence that manifests as strong surface winds, which can exacerbate a large conflagration.