VFR is not always VFR

I knew this would be a VFR trip and a low and slow ride across North Florida, South Georgia, and eventually Alabama. One of my stipulations for ferrying an unfamiliar piston airplane is VFR weather. This is non-negotiable.

The little Cherokee had solid bones but no frills. After about an hour in the sky, I noticed the horizon indicator tumble. My aviation-savvy nonpilot friend in the right seat noticed the vacuum gauge go to zero. The vacuum pump had given up. I continued the flight because the weather was still VFR and we had a wonderful natural horizon.

As we approached the Georgia line, the visibility began to change. Smoke from controlled burns combined with an inversion layer quickly started to eat away at my natural horizon. The persistent ridge of high pressure or sinking air aided in trapping the smoke in the first 10,000 feet of the atmosphere, right where most piston engine aviators spend their time.

This was not good. Despite airports reporting VFR conditions, I knew I needed to find a place to land. A quick glance at the iPad showed Valdosta, Georgia, was the closest airport, and I headed there. Despite the smoke, I was able to make a visual approach to the airport albeit with a bit of vectoring help from the controllers until I got close.

The lesson: Despite VFR conditions being reported and forecast, the visibility can still be IFR. Sometimes the lower visibility is a far enough distance between ASOS/AWOS stations that VFR conditions are still reported along the route, giving you a false sense of security.

This predicament could have been avoided with a bit more forethought on my part and a realization of the data available these days. As a meteorologist, I am often consumed with worrying about weather and visibility issues from the traditional culprits: thunderstorms, fog, and low ceilings. These days several data sources are available that allow reliable detection and prediction of smoke.

When the new generation GOES (Geostationary Operational Environmental Satellite) 16 and 17 weather satellites were designed, they were equipped with an Advanced Baseline Imager or ABI. The ABI tracks and monitors a wide variety of meteorological phenomenon far beyond just clouds. The instrument can also track smoke and dust particles. As a pilot, this is a helpful tool because you’re able to see smoke as well as dust in great detail. The GOES Image Viewer website from NOAA (star.nesdis.noaa.gov/GOES) is a resource of a wide variety of GOES satellite products including those that display smoke and aerosols that can limit visibility for pilots.

Let’s explain visible satellite imagery. It is almost like someone having a high-resolution camera in space and taking a picture of the Earth from more than 24,000 miles away. It is a great perspective. The biggest limitation of visible imagery is that it is available only during the daylight hours. Infrared imagery does not allow smoke to be viewed since you are looking at cloud temperatures to create an image. As shown in the satellite image, smoke is viewed as elongated, wispy, and somewhat translucent. The GeoColor True Color Daytime visible product is an excellent method to view smoke on a high-resolution Earth background. This data is updated every 10 minutes and provides useful information during rapidly developing natural disasters, routine weather, or in this case smoke. Plus, the GOES satellite is able to determine wind direction, allowing you to track where the smoke is moving using the GOES-derived wind motion. The computer generated wind barbs are overlaid on the satellite imagery, making for a fairly easy-to-understand map.

Based on higher resolution computer models—the rapid refresh (RAP) and high-resolution rapid refresh (HRRR)—we can predict where low visibility from smoke will be a problem. The HRRR-Smoke online tool from NOAA (hwp-viz.gsd.esrl.noaa.gov/smoke/index.html) allows multiple overlays and toggles to showcase smoke, surface-based smoke, visibility, and precipitation. This graphic is highlighting surface-based smoke based on the HRRR and where the smoke will likely be located during a given forecast timeframe.

The tool also allows you to show visibility in miles for a given timeframe with the ability to pan and zoom on the map.

The user can add as many overlays as needed to get good idea of the current visibility. Users can select either the RAP or HRRR forecast models. The HRRR has the advantage of 3-kilometer resolution, giving you a better picture of the upcoming weather. These smoke and dust forecast products are best used during the spring and summer when controlled burns and wildfires are more common. The visibility is usually even more reduced during the afternoon and early evening as the haze layer becomes more developed.

I have spent 26 years as a meteorologist and there is more weather data available to the public now than ever before. This data can be helpful in our flight planning, but it can also be like “drinking from a firehouse” to be able to determine what is useful, how to use the data, and where to find it. Had I spent a bit more time examining some key satellite data before I travelled to pick up the Cherokee, I would have been able to make a much better “go/no-go” decision.

JP Dice is a veteran meteorologist, flight instructor, and corporate pilot flying Cessna Citations and Gulfstreams.