Getting Weatherwise With Radar

Benjamin Franklin claimed, “Some people are weatherwise, but most are otherwise." As pilots, we need to be the former, and that certainly includes having a solid understanding of how to interpret and use radar weather information from multiple sources.

Panel-mounted GPS

Let's start by looking at weather displayed by a panel-mounted GPS. Our view will be somewhat generic to get the big picture of what we need to be thinking about. 

The first aspect is device configuration. If you hop into a G1000 aircraft with zero experience, your eyes and mind will quickly become overloaded with display and configuration options for a variety of MFD levels. Download the manual or read the physical one, watch G1000 videos, and become very familiar with how to select the options you want displayed.
 
You need to take your time and strategize how to approach learning whatever weather radar system is in your plane. For example, if your display is a touch screen, you’ll want to know your way around it and understand its quirks to avoid wasting time when you’re trying to find something. Booking time with a knowledgeable instructor who can walk you through exactly how things work can be invaluable. 
 
Ben Franklin also said, "You may delay, but time will not," which is why you need to know what kind of feed delay your system has. If you're flying 120 knots and the feed delay is six minutes, how far did you just fly? 

Yep, 12 miles. Penetrating the heart of a cell doesn't take long if you think you’re crossing behind it but are instead splitting it straight down the middle at night. The tail end won't be where you thought it would be at all, and the outcome of that decision could be less than favorable.

Non-panel Weather Radar Displays

Now, let's consider non-panel weather radar displays. A Sentry paired with ForeFlight will give you FIS-B (Flight Information System - Broadcast), which is great, but again, you need to know the delay time and how to configure ForeFlight to deliver what you're seeking. For example, the Radar (Classic) and Radar (Lowest Tilt) options make a difference in the density of display you see. Off the top of your head, do you know the difference between the two?
 
Radar (Lowest Tilt) gives you a look closer to the horizon. You'll also see more colors (intensity levels), of which you surely want to be aware.
 
But suppose you don't have an ADS-B receiver and only have your ForeFlight-equipped iPad with cellular service. The word that should occupy your attention is "intermittent." You might receive some degree of signal, and then again, you might not. So, is flying in or approaching questionable weather something you can foresee with a high degree of certainty? 
   
Nope. No brainer—don't bet on that lil’ pony to win.

Suppose all you have is whatever ATC is seeing on its radar. What does this really mean for you? ATC could be equipped with Terminal Doppler Weather Radar (TDWR). Even so, there are limitations like curvature of the Earth and distance, range folding (random streaks and lines that aren't actual storms), blind spots (can't always scan directly overhead), and false positives (bird flocks/ground clutter). There also can be time feed delays just as with on-board equipment.
 
ATC certainly can advise you of cell presence and location, which is especially helpful at night. It can tell you which way the cell (or cells) are moving. But if ATC doesn’t have Doppler (which you won't necessarily be aware of), it may just be seeing precipitation returns without more in-depth information. And remember, not all Class Delta airports have radar (e.g., KEDC, near Austin, Texas).
 
Since all flights originate on the ground, how about we consider using the radar display resources available to us while we’re still on the ground? There are several apps, like MyRadar, Doppler Radar - Live, Weather Radar NOAA, Windy, The Weather Channel, and, of course, ForeFlight. With each of these, the time display can differ, so again, you want to be aware of this. 

For example, with ForeFlight, when you hit the "Play" arrow while looking at radar, it runs through about a 45-minute spread, but it only shows you how the cell moved, not what its current and exact movement is at present. Even then, there can be about a 10-minute delay in the last display.
 
Radio detection and ranging (RADAR) is your friend, so long as you understand its functions and limitations. Heed Ben Franklin’s words, and be weatherwise with all the tools at your disposal. The guy certainly understood a thing or two about the perils of lightning striking a flying object. Plus, he’s on the 100-dollar bill, which gives his two cents a 5,000x multiple. That’s pretty powerful stuff, folks. 

Know Before You Go