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Feature Article 1

FEATURE ARTICLE

Matt Debski, Aircraft Owner WVFC tdebber@alum.mit.edu

 

Wildfire Season and Flying

The 2015 California wildfire season burned more acreage than any season in the past ten years.  This year was also the second time I've flown from the Bay Area to Portland during fire season.  These two flights, and others, showed me the necessity of developing contingency plans when flying within a hundred miles of a large wildfire.

A clear consideration when planning a flight during wildfire season is TFRs.  Wildfire TFRs can spring up overnight and change in size.  They keep firefighting aircraft separated from other aircraft.  These TFRs can be quite large, requiring a route around the wildfire and additional time and fuel.  For instance, a TFR over the Willamette Valley this summer required a significant deviation.  When getting your preflight briefing, pay attention not only to the existence of TFRs but also the reason for them, how long they've been in effect, and when they're predicted to expire.  These will all give clues as to the extent and severity of the fire within the TFR.  Note that while you may be able to fly legally on top of a wildfire TFR, it's not often a good choice.

The smoke from wildfires can extend for over 100 miles, causing reduced visibility up to at least fifteen thousand feet.  The first time I experienced this was during a mountain checkout in 2013, when the Rim Fire was burning near Yosemite.  The route my client and I had planned was to cross the Sierra along the path Route 50 takes from Placerville to South Lake Tahoe.  As we ascended over the foothills, reaching around 12,000 feet, flight visibility dropped dramatically.  While we were still legal with at least five miles of visibility, flying at that altitude in the Sierra with limited visibility is no fun and of questionable safety.  Also, it was unclear how much further the visibility would decline.  We made a left turn and crossed the mountains along Interstate 80 instead.  The extra distance from the fire made plenty of difference in visibility.

A few weeks later, as the Rim Fire was dying down and with different wind patterns, I flew across the Sierra along the originally planned route.  While visibility was reduced, it was ten miles or more.  The reduced visibility continued well into Nevada.

The most serious encounters I've had with reduced visibility around wildfires occurred this summer, en route from San Carlos to Troutdale airport near Portland.  I had already planned for the deviation from the most direct route around the TFRs.  Obtaining a weather briefing just before departing, I was pleasantly surprised.  The TAF for Troutdale and Portland called for no ceiling and good visibility.  In fact, it was probably the best forecast weather I'd ever seen going to Oregon.

The flight into Oregon from San Carlos was uneventful.  When we crossed the Oregon border, the plumes and clouds of smoke from the fires were visible.  However, it seemed as though remaining clear of the TFRs would be sufficient to also remain clear of the smoke.  As we passed Eugene, about 100 miles south-southwest of Troutdale, the ground became harder to see due to the smoke.  The in flight visibility at 7500 feet was still excellent.  On Flight Following, as we were passed to the next controller, there were several planes receiving IFR clearances into airports in the Willamette Valley.  In some cases, the pilots were executing missed approaches, meaning that the weather was bad enough that a landing was not possible even on instruments.  At this point, the ATIS at Troutdale was coming through.  The ceiling was 3000 feet but visibility was two miles.  This wasn't what I had been expecting, given the forecasted fantastic weather when we took off!

Fortunately, I was both IFR current and proficient for the conditions.  We received an IFR clearance to Troutdale and made an uneventful approach.  However, the smoke made our descent from 6000 feet down to 2500 feet solid instrument conditions.  Had I not been current or instrument rated, we may have needed to land over 120 miles away. The weather in Portland over the next 24 hours was surreal.  Ground visibility remained no better than two miles.  The next day, whatever weather pattern was bringing and holding the smoke north of Eugene cleared up.  The next two days were beautiful.

Departing from Troutdale, the weather was gorgeous.  However, the larger-scale weather pattern was now holding the smoke trapped between Eugene and the Siskiyous and Cascades.  Passing south of Eugene, flight visibility began to decrease at 8500 feet.  We climbed until we reached 10500 feet.  Visibility was better at the higher altitudes, but not great and still decreasing.  At this point, we obtained an IFR clearance.  There were other aircraft on frequency describing themselves as being in IMC.  As soon as we passed Lake Shasta and were out of the mountains, the smoke dissipated.  We had a smooth flight back to San Carlos.

In addition to the wildfire TFRs and news reports, there are a few other clues as to what the smoke situation may be.  Area forecasts (FA) will sometimes contain forecasts of the top of smoke as well as its coverage.  Area forecasts will be discontinued in 2016, but hopefully their replacement will contain the same data.  Terminal area forecasts (TAFs) will note smoke with FU after the visibility.  Unfortunately, the absence of smoke in a forecast doesn't mean you won't find it, but if it's there you're almost certainly going to experience it.

Flying requires constantly assessing the current flight conditions and choosing when to execute a backup plan.  When flying during wildfire season, take the possibility of reduced flight visibilities and ceilings into account.  Consider what alternate routes you may be able to take to avoid the smoke during the en route portion of your flight.  In the most severe cases, be ready to execute an instrument approach or to continue flying to an alternate if your intended airport is enveloped in smoke.

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