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Feature Article 1

FEATURE ARTICLE

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

 

Go/No-Go Decisions

Aviation periodicals are filled with Accident Analyses and Never Again stories.  These are usually offered as learning experiences, often on the judgment of the pilots.  Several of the West Valley Flying Club Newsletter articles have been similar flavors.  For this issue, I thought I'd offer a few brief synopses that are a bit more boring: cases where I elected not to continue with Plan A, and what ended up happening.

Markleeville Hiking

The most recent situation where this occurred was Tuesday May 12.  I had arranged for a day off work, had packed a pack, put my bike and hiking gear in the back of the car, and was ready to fly to Markleeville near Lake Tahoe for a day of bike riding and hiking.  I'd been looking forward to this trip for over a month.  I had been watching the weather throughout the week and noticed that a low pressure system would be moving into the area, bringing with it high winds.  The night before my departure, the winds at 9000 and 12000 feet during the time of my arrival into the area were forecast at 24 knots and 33 knots respectively.  Mountain flying guidance says to consider staying on the ground when winds are over 20 knots and do stay on the ground when they're over 30 knots over the ridges.  Still, the 33 knots was pretty close to 30 and I was hoping the forecast would be better the following day.

On Tuesday, I woke up to find that indeed the forecast and improved slightly and the 12000 foot winds were now at 27 knots.  After looking over the full briefing, I headed to the airport to preflight.  After unlocking the plane, I reconsidered the forecast and the trending conditions.  Things were unlikely to improve during the day.  The consequences of underestimating the winds were potentially severe.  I locked the plane back up and headed home, disappointed.  Of course at this point I'd already made the right decision, given the risk factors.  However, looking at the weather reports later in the day indicated the winds at 12000 feet were at 44 knots.

Yellowstone Return

Coming back from Yellowstone one summer, I stopped with my backpacking buddy in Elko, Nevada to get gas and check on weather before crossing the Sierras.  Looking at the forecast and the weather radar, it was clear that we wouldn't be departing in the next hour or so: isolated thunderstorms were predicted to pop up all afternoon and there were spots of red for a hundred miles in either direction from where we'd hope to cross.  Still, I hoped that the storms would die down as the afternoon wore on and we'd still get home that evening.  An hour or two later the storms were still popping up.  This decision was pretty clear: we called a nearby hotel and the shuttle van came to pick us up.  My friend and I had a great Basque meal and the shuttle driver pointed out the local brothel (we didn't visit).  The following morning we were up early to get a start before the thunderstorms starting popping up.  We passed well clear of one cell about forty miles outside of Elko and made it over the Sierras with clear skies.

Forest Fire

In 2013, the Rim Fire burned for eight weeks just outside Yosemite.  I had been contacted to do a Mountain Checkout. I asked my client to choose from a number of airports that met the criteria for a Mountain Checkout and plan the flight.  Either South Lake Tahoe or Alpine County was first on the list.  The area forecast mentioned smoke aloft at the altitude we'd be flying at.  As we approached the western side of the Sierras, visibility dropped slowly but steadily.  As the foothills grew taller, my client recognized that he was having a hard time seeing the ground and forward visibility had decreased to less than ten miles.  We briefly discussed options and elected to make a turn to the north.  As we got farther from the fire, visibility improved dramatically.  We proceeded to Blue Canyon and Truckee airports.  We were able to complete the checkout by executing a well-considered second option, rather than continuing into deteriorating conditions or simply returning home.

Western Flying Adventure

My family and I were flying from San Carlos via Elko (again) to Bozeman, Montana.  After spending a planned night in Elko, I obtained a weather briefing and noted that thunderstorms were a possibility along our planned route of flight.  In this situation, however, the weather was forecast to be developing west of our planned route, which was almost perfectly northeast.  Additionally, along our route of flight lower terrain consistently remained to the northeast, with many small airports along the way as escape routes.  Although the weather forecast was not what I hoped for, there were enough escape routes and options that we elected to depart for Bozeman.  Along the way, I got updates from Flight Watch about the developing weather.  With the exception of one rainstorm which was dramatically visible but far to the west, the predicted thunderstorms were actually developing later than expected.  My family and I were able to safely complete our flight, hours before the weather moved in.  In this case, we could of course have been conservative and remained in Elko, but the myriad options gave me the confidence to fly as planned and get an extra day in Bozeman.

These scenarios have mountain flying in common.  In general, flying in the mountains presents greater hazards and uncertainty than flying over the Central Valley.  However, even flights in the Bay Area can present questions about when the right time to depart is in the face of slow-to-burn-off fog or the strength of crosswinds in the winter.  Most of us have these tales of when we were happier to be on the ground wishing we were up than we would have been in the air wishing we were on the ground.  With general aviation, it's important to remember to constantly be evaluating the current situation and the plan, and to be open to changing the plan if the situation is worse than expected.
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