![Sometimes the most critical lessons for pilots come from understanding what actions to avoid. [Credit: IFR Magazine]](https://flyingmag1.b-cdn.net/wp-content/uploads/sites/2/2025/09/FLY0925_1.9-IFR.jpeg?width=1265&height=876)
Pilots know well the emphasis on checklists, procedures, and best practices. These are things that deliver positive results to keep us working safely and efficiently.
But sometimes the most critical lessons come from understanding what actions to avoid. In aviation, a single poor decision can cascade into a dangerous situation with great speed.
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So we’re going to flip the script and explore some things not to do in regard to aviation weather—those habits, misconceptions, and mistakes that lead down a long path that could end with a National Transportation Safety Board (NTSB) report.
I hope that by covering these negative aspects of aviation meteorology we can all build a more comprehensive safety net for ourselves and learn some interesting concepts in the process.
Overconfidence
I used to be a storm chaser during the 1990s and early 2000s, and I eventually authored a 300-page book called the Storm Chasing Handbook. Since then I have dropped out of storm chasing for a few reasons—a new family and the growing dangers from “chaser circuses” and the crowded roads close to storms.
But I also find myself a little more worrisome of storms than I used to be. In those early days, ignorance was bliss. The more I study storms, and the more I look at radar data (with 372 case studies on my hard drive), the more I’ve seen how common powerful circulations and dangerous structures are, even in weaker storms.
From a meteorology standpoint this makes storms even more fascinating to study, but it also makes me concerned when it comes to safety.
In my library there’s an old Air Force technical report from 1970 that explored weather procedures at airlines like Continental, Braniff, and Delta. In those pages, it summarizes thunderstorm safety with the simple sentence: “Treat every thunderstorm as a hazardous one, and avoid rather than penetrate thunderstorm activity.”
This deserves consideration, because thunderstorms are, by nature, chaotic processes. Even with the best radar analysis tools, and a wide array of velocity, spectrum width, and dual-polarization products, it’s often difficult to mentally integrate exactly what’s taking place in a storm.
Even the seemingly weak “air mass storms” can develop brief dynamic circulations, as in the case of the Delta L-1011 disaster at Dallas-Fort Worth (KDFW) in 1985 and the Pan Am 727 crash at New Orleans (KMSY) in 1982. Both of these events took place in the Southern states during the stagnant months of midsummer, and none of them were foreseen.
So I am taking this moment to draw on my decade of storm chasing and 35 years of meteorological experience to reiterate that call to treat every thunderstorm as if it were severe, and give them as much space as you can allow. You can certainly roll the dice flying into one, but why take that risk when other options are open.
Old Radar Imagery
Many of us have become accustomed to using radar apps. It’s easy to forget there’s a long process that goes into creating the data. First the WSR-88D radar site has to gather the data. Then the information has to flow out of the radar site over wideband data lines to a distribution service, then to your app.
In the midst of this flow of data, it’s quite common for delays and outages to silently appear in the process. Radar sites occasionally drop offline during heavy weather, sometimes due to equipment damage, other times from communications outages. When it happens, it’s easy to miss the moment when data stops flowing. Imagine making a decision without realizing you’re looking at old data. It happens, and every seasoned forecaster has seen that.
For this reason develop a habit of double-checking the radar product time and making sure the radar picture agrees with the weather you’re seeing.
When critical decisions are on the line, pull up a neighboring radar site covering the same area and check another radar source. Make sure these pictures match up with the weather you’re seeing outside or with what satellite and surface data you can obtain. Radar mosaics blend data from multiple radar sites to present a regional or national picture. You should never use these for tactical navigation, because these are typically updated as infrequently as 10 minutes and not when each radar scan comes in. There will be additional latency on top of this, since radars are in many different stages of their scans, all of which take several minutes.
If you must navigate through storms using NEXRAD images, use only single-station imagery from a nearby site. Depending on the app and source, single-station imagery might arrive less than 60 seconds after the product was generated. But monitor the product time.
Also remember that standard 0.5-degree imagery only samples the lower atmosphere, so use the composite reflectivity product rather than base reflectivity to see the maximum detected value at all elevations. When flying directly over a radar site you will be over the “cone of silence,” since the antenna can’t tilt higher than 20 degrees. So when you’re within about 20 miles of a radar site and above 10,000 feet, you should choose a different radar site.
If things get difficult, cut your losses and get assistance from air traffic control (ATC). It has the weather on scopes and can give you a good vector away from the worst hazards.
Microbursts
We all know how ground schools drill aviators into respecting the thunderstorm. Give them a wide berth and you’ll avoid their many hazards, including microbursts.
But this oversimplification can lull pilots into a false sense of security. While microbursts are indeed often associated with convective activity, they can occur without thunderstorms.
Virga can be a major source of downbursts and turbulence, and it doesn’t require a storm. All it needs is moisture and instability in the middle troposphere, and lots of warm dry air near the surface. In forecasting we refer to this as an “inverted-V profile,” referring to the telltale appearance on Skew-T diagrams. When elevated precipitation forms, it produces large cells of precipitation that evaporate on the way down. The precipitation stops, but the momentum doesn’t.
Evaporative cooling combines with dry air entrained in the sinking downdraft cell, increasing the downward velocity. When the downdraft reaches the surface, we get strong gusty winds, strong low-level shear, and we occasionally get visibility restrictions from blowing dust. The risk to aviation is that the downdraft speed can exceed the climb rate of your airplane. This can certainly be a problem when there’s cold air aloft and you’re heavily loaded.
So when you see the telltale streamers hanging down from a mid-level cloud layer, it’s a good sign to be on guard and monitor what’s going on. Remember, the danger zone extends well beyond the visible precipitation.
If the conditions at your airfield get out of hand, it may be a good idea to divert until things settle down. Virga usually clears up within an hour or two. If you haven’t taken off yet, maybe it’s a good time to wait a bit.
METARs Can Lie
METAR reports only observe the cloud conditions at the reporting airfield. Even worse, ASOS systems have no ability to see what is going on around the airfield and off in the distance. The ceilometer only observes conditions along a vertical axis.
For pilots who fly frequently in mountainous terrain, these peculiarities are well understood. But for others, this can be a big risk when you’re flying cross country into unfamiliar areas. The METAR at Salinas, California (KSNS), can be much different down the valley at King City (KKIC), which has no ASOS site.
This is where it’s important to look at a surface chart, such as the one at AviationWeather.gov to look at all stations and get the big picture. Check out the closest TAFs to try to assess what ceilings and visibilities are at various airports. Most electronic flight bags (EFBs) and Internet aviation sites like SkyVector.com allow you to see an airport’s METAR and TAFs directly from the chart.
Also use satellite data to properly size up the cloud situation. Some of the best satellite images I’ve found are at College of DuPage Weather (weather.cod.edu/satrad), which includes the very important zoomed images of different regions and localities. There’s no reason to be using poor-quality, coarse imagery in 2024.
College of DuPage also provides the amazing multispectral “NT Microphysics” images that will let you see all the hidden fog and stratus layers at nighttime. I wish we had these tools 20 years ago. They are incredible products, and I invite you to take a look.
Look Beyond the TAF
At a big airfield, it’s easy to think that its TAF is all you need. But a TAF has very limited scope, and there’s also the issue that only one forecaster is looking at the weather there.
One easy trick is to check a military airfield nearby. These are produced by different forecasters. (I wrote TAFs for Dyess Air Force Base, while the National Weather Service at Fort Worth composed TAF for Abilene Regional Airport [KABI] in Texas 8 miles away.) If the airfields are reasonably close and the terrain is similar, you can compare the two to look for any unexpected ceilings, visibility restrictions, or precipitation. It’s confidence building if they look the same. But major disagreements are a sign to dig deeper.
It also pays to view the AviationWeather.gov site, Weather > Forecast, and look at the ceiling, clouds, and precipitation fields. These come from some of the best model data available and provide a second look to help put the TAF into context.
Model data has long had a tarnished history, right up through the 1990s and 2000s. But there have been vast improvements in quality. I was once skeptical of model data, but the improvements over the past 15 years have been tremendous. So definitely check out some of these tools. It takes no more than a minute to look at the key fields for your destination.
Also TAFs only extend 24 to 30 hours out, so if you’re arriving toward the end of this range, you might be dealing with unforeseen changes. Checking the local public forecast helps give you the big picture and some awareness of what issues might be coming.
This column first appeared in the September Issue 962 of the FLYING print edition.
