Radar and Drift

Radar and Drift

Radar and Drift

Radar and drift. I bet you’ve never heard those words used in the same sentence. Fading, attenuating and even marching are interesting words occasionally used with the term “onboard radar” – but drift? Yes, drift has an important meaning when it comes to using onboard radar. However, my contention is not that the radar itself drifts, but that our use of onboard radar can drift. Let’s explore.

The Meaning Behind Drift

Drift is an interesting word. We use it frequently in aviation, but mostly in relation to a takeoff or landing as in “I drifted off centerline.” Or on a cross-country, I might “drift off course.” Or during an IFR flight, a pilot might “drift off altitude by 100 feet.” In each of those situations, there was a standard (centerline, course, altitude) and drift means an unintentional movement from that standard. Drift is an enemy to aviation and one that every pilot needs to keep a sharp lookout to avoid.

During refresher training, there’s another form of drift that I intentionally look for – drift from known standards and practices. You’ve probably heard this before: “I used to do it this way, but I started doing it that way.” I see it often when pilots of one particular airframe talk to a pilot (or well-meaning, but uninformed CFI) who operates a different type of airplane. Practices that work well for one airframe may not work well for another. When these practices are errantly transferred to the different airplane, drift occurs. I see it frequently in refresher training, and it’s one of the reasons that every twin and turbine pilot should pursue type-specific training, not just training from a local CFI. The CFI may be highly-competent yet does not know much about the specific airframe you operate.

So, how do drift and onboard radar fit in the same sentence? The connection lies in defining the standard from which drift can occur. When it comes to thunderstorms, the standard is every pilot should remain 20 miles from thunderstorms and should not drift closer. But here is an example of how drift can still happen.

Drifting Too Close

A few years ago, I flew in an MU2 Marquise with a veteran airline and commercial pilot. Our flight was from Montreal, Canada back to Texas, and after flipping a coin, it was determined that I was to be the left-seater for this long flight. Draped across much of the United States on this summer afternoon were splotches of slow-moving thunderstorms, and inside some of the bigger splotches were some fairly intense cells. We climbed up to the smooth, clear skies at FL260, well on top of everything except for the convective stuff punching through the haze layer. We settled down to what appeared to be an easy flight.

About two hours in, we started receiving the normal calls from ATC advising of “scattered moderate to extreme cells from our 10 o’clock to 2 o’clock,” along with the usual “cleared to deviate right and left of course, advise when direct destination.” There were plenty of holes in the scattered cells, so my veteran pilot slipped off to the empty cabin for a short snooze (yes, the MU2 is a single-pilot airplane).

I then fired up the onboard radar, had downloadable radar on the GTN750, and contrasted everything against what my eyes were seeing through the front windscreen. I remained in the clear, smooth air and weaved around scattered cells somewhere over Indiana. Picture a rather boring flight with the autopilot on HDG mode and my guiding the airplane along through the cumulous valleys. Nothing to it. We’ve all been there – 5 degrees right, 10 left, just a little touch of the heading bug back and forth.

After about 30 minutes or so, my bored friend woke up and stuck his head in the cockpit to “check in” and see our progress. He looked out the left window and said frightfully, “What are you doing? That’s a thunderstorm right there!” 

Rather offended, I showed him the radar showing that we were in the clear, and I pointed to the blue sky that dominated the front windscreen. He merely pointed to the cell not too far out the left window and said, “You are crazy!” 

He plopped down in the right seat, belted in, and told me my risk meter was broken. Of course, I took serious offense, sulked quietly, and turned the heading bug 5 degrees more right. There was no turbulence, nothing that would have even awoken a sleeping passenger, but he was right. My risk meter was broken. I had drifted from a position of being respectful of thunderstorms in my early years in aviation to a point that I was willing to go between cells, cut corners around cells, and generally “just get too close.” I had appropriate confidence in my ability to operate onboard radar and stay out of the convection (and associated updrafts and downdrafts), but the convection is only one threat on the long list of threats a thunderstorm can provide. The threat of lightning and hail are ever-possible with any thunderstorm, and distance is your best friend when avoiding these enemies. The FAA standard to remain 20 miles from any thunderstorm had faded through many “uneventful close encounters” with cells. I had drifted from that standard to the point where I got comfortable and flirted with disaster.

Want proof that being close to a thunderstorm is no good? There are three PA46 owners I know who have sad tales to tell from thunderstorm experiences in 2018. These are certainly lessons you want to learn from others’ mistakes as opposed to your own.

Lessons Learned

The first is a Meridian owner who flew about five miles from “a small storm that didn’t look like much at all.” The flight seemed normal, and no one onboard noticed anything unusual in flight, but upon landing it was apparent that lightning entered at a prop tip and exited via a static wick on the tail. While initially appearing to be minor damage with minor ramifications, the extent of the financial and scheduling pain was soon felt. 

Due to the lightning strike, the engine had to be removed from the airframe and disassembled so the parts could be demagnetized. This took four months, and even though insurance paid for part of the invoice, there were still large costs associated with “betterment” – a really nasty word in the insurance industry for any airplane owner who doesn’t keep large amounts of cash-reserve. 

The second story is of a JetPROP pilot who flew in the clear between two cells at FL270. He remained in the clear, but then heard some unusual sounds while in flight. Upon landing, there were dozens of pockmarks in the leading edges of the wings, tail and nose area. Hail had been thrown from the storm and he flew through the onslaught. The airplane will fly again but with lots of repairs, $30,000 in new deice boots and a newfound appreciation of the power of a thunderstorm by the pilot.

The third owner story is a Malibu pilot who never even knew something happened. But during the airplane’s annual, the entry and exit wounds of a lightning strike were discovered. The airplane was repaired, but “avionics gremlins” continue to show up a year after the suspected day of the strike. 

Each of these airplane owners will suffer the most financial loss when they try to sell their airplane. Buyers of airplanes are justifiably wary of airplanes that are damaged by lighting or hail. Damage history significantly lessens the value of an airplane.

Needless to say, the owners now steer clear of thunderstorms and would relate that the downtime, financial loss and heartache was absolutely not worth the few minutes saved by skirting a thunderstorm. It is simply not worth it. You might get away with it once, twice or a hundred times, but if you play with snakes, the snake will bite somewhere along the way – and the strike could be deadly. And a thunderstorm is no garter snake; it’s an emotionless viper full of deadly venom.

Closing Thoughts

While I’m a big believer in onboard radar, I’m not a believer of using onboard radar to skirt a storm. The pilots who “go tactical” should avoid the most potent of the deadly venom (storm convection), but going tactical can lure you close enough to the storm so that lightning and hail can ruin your day, your airplane or even your career if you are a professional pilot. 

If you have onboard radar in your airplane but don’t know exactly how to use it, don’t even think about going tactical near a thunderstorm. In my experience as a long-time instructor in the twin and turbine community, most pilots do not know how to properly operate onboard radar. Some have been to a classroom-only radar class, but the vast majority have not experienced years of mentorship by a true radar veteran (like most airline/military pilots), and don’t have the experience to roll the dice around thunderstorms. 

Operating onboard radar is an art and a science. You need to understand how it works, and you also need the real-time experience to make it tell you where the deadly snake lies. If you blunder into a thunderstorm, you’ll either not live to tell the story, or the story you tell will be of sheer terror and a bent airplane. The convection in a thunderstorm is greater than you or your airplane can handle; a thunderstorm will win every time. Avoidance is your only option. Drift away from thunderstorms, and the life you save may be your own. 

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