Trying to reason with thunderstorm season

By JEB BURNSIDE.

Welcome to the first of what is planned to be a monthly installment about pilots. We’ll look at how well they aviate, how poorly, and how they can do better. We’ll pick apart news items affecting them, and also have some thoughts about their future.

It’s that time of year in the Northern Hemisphere, when warmer temperatures easily translate into thunderstorms, making them much more prevalent.

With that in mind, a friend called the other day to pick what’s left of my brain on how to plan an upcoming cross-country. And by “cross-country,” I mean crossing the country: He’s based in the Pacific Northwest, and has business in South Carolina. He’ll be flying a fixed-gear Cessna single.

He’s instrument-rated, and an accomplished pilot and aircraft owner, but hasn’t had much experience crossing large sections of the country and dealing with weather patterns. I’ve done more of that kind of flying than he has, and he had a few questions. (Meanwhile, if I needed some advice on getting in and out of remote, back-country airstrips or mountain flying, he would be my go-to guy.)

We both were in front of computers, so we brought up a site displaying real-time Nexrad weather radar and started playing what-if.

On that day, a cold front was forming a slight bow, extending from Michigan to Texas. It was a varied mass of green, yellow and red, with a slight gap just west of Paducah, Kentucky (KPAH). He asked me if I’d try to shoot that gap. The quick answer was “yes,” but came with some caveats.

Stay Visual

My first admonition was to remain in visual conditions at all times when near thunderstorms. That way, of course, you’ll never fly into one. Staying in VMC also enhances situational awareness by allowing us to keep in sight the things we’re trying to avoid. And unless something behind us closes our escape route, we’ll always be able to do a 180 and try something different.

Another reason is certain combinations of lighting, perspective and cloud color can trick pilots into thinking there’s blue sky through that gap up ahead when in reality it’s just more cumulonimbus. And if you’re looking at them up close and personal while trying to find a gap, it’s a good idea to do so both with and without sunglasses, which can mask some of those colors but help with depth perception by minimizing glare.

We also talked about ways to use Nexrad imagery while airborne. We’re really spoiled these days with Nexrad in the cockpit via ADS-B In or SiriusXM Aviation, but some additional caveats apply. One of them is the latency involved.

The ground-based radar system scans the sky around it, processes that data, turns it into images and delivers it to whatever service you use before uploading it to your aircraft. That can take a while — up to 20 minutes, according to the NTSB — and a lot can change in that time. What you’re looking at out the window isn’t what’s on your Nexrad, and vice versa.

Another Nexrad-related caveat is to not make the mistake of thinking a depicted gap in a cold front means severe clear weather. We both pulled up the Metar for Paducah and noted it was advertising something like 2,500 overcast and five miles. That’s decent weather at the surface but it’s likely there were layers above that overcast up into the flight levels, one of which easily could have been at cruising altitude.

And just because Nexrad wasn’t painting anything right then, it doesn’t mean there wouldn’t be something there in 20 minutes or so.

Get Upwind

Another thought we discussed was how, in fact, to shoot such a gap. The cold front generally was moving from the west to the east, but the flow along the front itself was from the south-southwest. That was evident from Nexrad’s depicted cell movement along the front, as opposed to checking the winds-aloft forecast. I strongly suggested he would want to proceed slightly past his intended gap before turning and shooting through it to take maximum advantage of his speed advantage and avoid lingering in the “danger zone” any longer than necessary.

Regardless of whether we’re flying a Boeing or a Beechcraft, the one tool we all have when dealing with thunderstorms is our aircraft’s speed and maneuverability.

Weather systems, on the other hand, typically are large masses of air that don’t move as fast as we can and rarely make abrupt direction changes. (If you find a cold front or thunderstorm is matching your airspeed, that’s a good indicator you should land somewhere and wait for it to move off — or get a faster airplane.)

By flying to a position upwind of a gap you want to fly through, then turning toward it and doing the deed, you might lose a few minutes, but you’ll gain a tailwind, at least while aimed at and moving through the gap. Doing so minimizes your exposure and restores your relative speed advantage, allowing you to get through the gap and past the worst weather as quickly as you can.

The kind of gap we’re thinking of, of course, is a “real” gap, one with visual conditions. And if you’re living right, that tailwind might also carry you the rest of the way to your destination.

There are a host of other considerations when considering thunderstorms, including terrain and airspace, on-board fuel, available divert fields and their weather, and much, much more. Sometimes, the best decision is not to fly at all, or to land and let the nasty stuff move over and past you.

And remember: Never, ever fly into a thunderstorm unless you have no other choice. And you always have other choices.