Briefing the Canadian Wildfire

Among the top news stories of recent days have been wildfires raging across Canada and the northern United States. In the last day or two, significant smoke levels have made their way south into the midwestern and northeastern United States. 

I took an interest in the topic on my commute from central Pennsylvania back to Chicago on Thursday as I prepared for a mid-morning report time on Friday. Pulling up to the State College Regional Airport, I noticed a blanket of smoke covering the airport and surrounding areas, and from arriving at the airport to closing the main cabin door for pushback, the smoke was thick enough at times to cause mild eye irritation. More on the systems that keep smoke out of the aircraft in flight in a few minutes. 

This situation necessitates a quick check of a few considerations relating to the implications that this level of smoke has on flight operations. I’ll begin with a quick note on how to handle the immediate vicinity of fires and then a broader discussion of how to deal with the smoke in the U.S.

Watch Out For Popup TFRs

During my first flight instructing job in central Florida, controlled burns were a common occurrence in spring and summer. On occasion, the FAA puts Temporary Flight Restrictions (TFRs) in effect to protect what occasionally becomes high volumes of aircraft in taking part in fire management, whether or not the fire was planned. Even without the TFRs, the FAA often recommends avoiding the immediate vicinities of fires to reduce the increased risk of midair collisions caused by reduced outside visibility. 

In areas where wildfires are more prevalent, certain airports are known as bases for aerial firefighting operations and become even busier during peak firefighting. In any case, if you find yourself flying in the vicinity of a fire or at an airport known for its firefighting operation, increased vigilance, keen traffic management, and clear radio communications are necessary to ensure safe aircraft separation, no matter the environment. 

In the current smoke situation across the U.S., vigilance is required for a different reason. Smoke can be deceptively thin, and climbing or descending through it may prove more challenging than initial appearances would suggest. The important factor to consider is just how starting a sudden encounter with IMC by way of surprisingly thick smoke can be for a pilot who is not prepared to rely on their flight instruments to sustain safe flight. 

An FAA study finds that 26% of aircraft and 22% of pilots involved in VFR into IMC fatalities were equipped, qualified, and current to fly under Instrument Flight Rules. These deaths are easy to write off as those that “always happen to somebody else,” but data proves the opposite. Often, it is when qualified, current pilots flying capable airplanes encounter deteriorating conditions that they didn’t prepare themselves for that these crashes occur. Put another way, we are often more vulnerable due to startle and surprise (as, for example, when the conditions “don’t really look too bad” before we enter them) when these conditions come up. 

A proper understanding of the extent to which smoke can impact flight viability is critical to ensuring safe flight. Be cautious of underestimating how it may look at face value. 

A Very Brief Systems Review

Another question is how this wildfire smoke affects aircraft operation beyond requiring the extra Air Traffic Control separation for instrument conditions. In the short term, there may not be much to notice, but long-term exposure to smoke could cause an engine’s materials to deteriorate faster. This really means that an engine may need special attention during a standard inspection or, if facing heavy exposure over a period of years or decades, may be retired sooner. Particulars may also slightly increase the chance of an engine failure or abnormal condition, particularly if it is not maintained well. However, I think that systems such as engines on commercial aircraft in the U.S. are maintained to a high enough degree to prevent most or all serious issues due to the strict performance tolerances the FAA expects not only from aircraft manufacturers but also the maintenance departments of the airlines and other operators that the public trusts for their care. 

General Aviation pilots may need to be a little more vigilant during magneto checks on run-ups if wildfires have been prevalent lately. For a similar reason, I would not be shocked if the bill for cleaning out buildups from engine cylinders is slightly higher on the next 100-hour or annual inspection. 

O'Hare shrouded in smoke

And if you’re concerned about the air quality inside the cabin of a jet, consider that the aircraft already has a system to filter particles out of the air before it gets to you. Airlines made a point of sharing the new HEPA filters they were installing during the COVID pandemic, but in many cases, the aircraft being highlighted had these filters or systems that had comparable performance. 

Without getting too deeply into aircraft systems here (that will come eventually), cabin air on commercial jets is pulled from something called the “bleed air” systems on the engines. Jet engines have compressor sections that bring air to high enough power to combust and produce thrust; before combustion occurs, bleed air is pulled from these compressors for cabin pressurization, air conditioning, and other environmental controls. 

The system was already designed to send the air through environmental PACKS that cool and filter the air before reaching the cabin. This prevents super-heated, contaminated engine air from flowing into the cabin. These filters also do a good job at removing smoke, dust, and viruses from the air by continually filtering new outside air to fill the cabin. 

Anyways, gotta run. Leave a comment down below if I got something wrong or it you have something to add. Look forward to chatting again soon.