Plane & Pilot
Tuesday, November 6, 2012

IFR Strategies In Convective Weather


A tactical flight from coast-to-coast in a Columbia 400 from above the weather to underneath the overcast



A Garmin G1000 screenshot of the final part of the original route to Erie. Each of the red and white squares are individual cells with an arrow showing their direction of movement. Joe Shelton turned north to stay on the upwind side of this gauntlet. 
It may sound like we departed on a wing and a prayer. But, I had a simple plan. Remain on top in VMC conditions as long as possible and since the ceilings were forecast to be high enough to fly safely underneath, stay on top until it became necessary to descend below the ceiling to complete the trip. I had a set of guiding criteria. First, the ceilings had to remain high enough for continued safe flight through to the destination. Second, we'd remain predominantly VMC on top until that became difficult. Third, a descent through anything more than light icing conditions was unacceptable. Fourth, there had to be a golden escape alternative at all times. We departed with about six hours of fuel on board, so, if nothing else, we could do a 180 and easily return to a clear airport behind us.

With those criteria firmly in mind, we continued northeast. The scattered-to-broken undercast eventually became solid, and the tall and sometimes ominous lines of buildups to both our right and left became more imposing. The severity of the two lines was confirmed on the weather page on my Garmin G1000's MFD.

I comfortably punched through a few benign-looking clouds and asked for deviations around a couple of more ominous buildups. But unlike some days where you can watch the cumulus rise, on this day, the clouds we were passing didn't seem to have much instability.

At one point, I was looking at a buildup directly ahead and decided that while it looked benign, it probably warranted deviating. When I asked for a deviation, Center wondered why because their radar wasn't showing anything. An "aha" moment: Always ask for and use Center's radar eye and experience; they're there for you. But don't ever believe that they know more than your eyes tell you. It takes water droplets for radar to show anything, and this about-to-be thunderstorm wasn't mature enough yet. We received clearance for a deviation and skirted the buildup, but there was enough instability that we could feel turbulence even though we were miles upwind of it.

You've probably heard that you shouldn't rely on satellite weather for tactical guidance. Nothing I've seen disputes that fact, especially with fast-moving weather. But there are a lot of different types of weather information available, so when the weather is questionable, be sure to continually review everything that satellite weather offers. It's very useful for understanding the big picture and tracking weather patterns. I kept my eye on the Erie area weather throughout the trip, and periodically checked the current METAR, after verifying the reporting time, so I'd have a sense of whether we could make our destination.

I periodically turned on Cloud Tops and then Echo Tops to look ahead, so I'd have a sense of how long I could expect to stay at my cruise altitude. Technology aside, I knew it was going to be my Mark I Eyeball that provided the final weather navigation.

As we continued toward Erie, I continued to cycle through almost all of the weather information available through the G1000. My challenge was how to track the surface weather while continuing to monitor the rest of the weather picture. The G1000 has a feature on the weather page called METAR that displays a flag by each airport icon indicating whether that airport's last transmitted METAR was VFR, LVFR, IFR or LIFR. By turning on the METAR display and checking the actual reported weather at selected airports, I kept a running situational awareness on the weather below the overcast. I also kept Flight Watch active in the background, so I'd hear any information germane to my routing. In such a case, I listen for what the specialist tells others, but also listen for PIREPs for things like ice, turbulence, etc. (On a prior flight, I had once heard that my destination had gone below minimums over an hour before I'd have been in range to hear the ATIS, so I had plenty of time and fuel to plan a diversion.)

About this time, ATC offered that it looked like our clear route was beginning to close, and they recommended that we accept a deviation to the left to avoid the significant weather. That was an acceptable option because it would keep us out of the dual thunderstorm-line weather gauntlet and to the west of the more intense weather. It would also keep us upwind of all of the current cells. If you have the choice, always try to remain upwind of significant weather because the weather could move faster than planned or than SatWeather shows.



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