Flying - - CONTENTS - By John Zim­mer­man

Five key rules for bet­ter de­ci­sion-mak­ing when fly­ing with datalink weather

Here’s an emerg­ing safety story that hasn’t re­ceived much at­ten­tion: Fa­tal ac­ci­dents caused by weather are de­clin­ing. No­body should be pop­ping Cham­pagne bot­tles just yet, but there is enough data to sug­gest a steady down­ward trend over the past few years.

What’s the cause of this en­cour­ag­ing course re­ver­sal? There are prob­a­bly many, but the in­creas­ing use of datalink weather in the cock­pit de­serves se­ri­ous at­ten­tion. Over the past 10 years, the num­ber of pi­lots fly­ing with some type of cock­pit weather, typ­i­cally ei­ther ADS-B or Sir­iusXM, has ex­ploded. Por­ta­ble ADS-B re­ceivers in par­tic­u­lar re­ally took off about five years ago, right around the time the fa­tal weather ac­ci­dent rate started de­clin­ing.

Datalink weather is hardly a mir­a­cle cure, as the Na­tional Trans­porta­tion Safety Board and FAA have fre­quently re­minded pi­lots, but the data cer­tainly is sug­ges­tive. The lim­i­ta­tion we con­stantly hear about is that radar is not real-time: Those images are de­layed, some­times by as long as 20 min­utes, so they should not be used for close-in storm avoid­ance. That’s crit­i­cal to re­mem­ber dur­ing thun­der­storm sea­son, but un­for­tu­nately, the gov­ern­ment drum­beat about this mi­nor lim­i­ta­tion has ob­scured the huge in­crease in safety that’s pos­si­ble with this in­creas­ingly ad­vanced equip­ment.

The key word there is pos­si­ble. Tech­nol­ogy is rarely good or bad; it’s merely a tool. To make datalink weather a tool that im­proves safety, it has to be treated with re­spect. That means un­der­stand­ing the on­board avion­ics at a deep level, whether it’s a fully in­te­grated glass cock­pit or a por­ta­ble ADS-B re­ceiver, and mak­ing it part of reg­u­lar re­cur­rent train­ing.

Some real-world weather fly­ing ex­pe­ri­ence is also a must, since the most valu­able lessons sim­ply can­not be learned from a text­book. A safe pi­lot is a weather geek and seeks out op­por­tu­ni­ties to fly (safely) around dy­namic weather con­di­tions. Af­ter 15 years of mak­ing these flights with datalink weather, I’ve changed how I fly cross-coun­try trips, both VFR and IFR. I’ve also de­vel­oped a few rules for us­ing datalink weather. These aren’t com­pre­hen­sive, but they help struc­ture my de­ci­sion-mak­ing. 1. Un­der­stand the big picture first. A doc­tor wouldn’t op­er­ate on a pa­tient with­out first un­der­stand­ing the un­der­ly­ing con­di­tion, and nei­ther should you read a metar with­out first con­sid­er­ing the over­all weather sys­tem you are fly­ing in. The first step to safe weather fly­ing starts on the ground, where you de­velop a the­ory about what’s go­ing on

in the at­mos­phere. That comes from re­view­ing the sur­face anal­y­sis, the up­per air charts and the fore­cast dis­cus­sions. Find out where the lows are, where the fronts are mov­ing and what the winds aloft are do­ing. This big picture sets the rest of the weather in­for­ma­tion in con­text, but it of­ten isn’t given the im­por­tance it de­serves.

2. Take in enough data, but not too much. Once you have a the­ory, it’s time to go fly­ing and test that the­ory by ap­ply­ing real-world data to it. For­tu­nately, pi­lots have more data at their fin­ger­tips than ever be­fore, so it’s easy to get a de­tailed picture of the at­mos­phere around the air­plane. Un­for­tu­nately, all this data can lead to two mis­takes. First, you can’t get so locked into the col­or­ful radar im­age that you ne­glect other weather prod­ucts, such as metars, TAFs, pireps and winds aloft. Radar is fan­tas­tic, but it’s only a part of the story.

At the other ex­treme, it’s easy to get over­loaded with data and ei­ther for­get to fly the air­plane or talk your­self in cir­cles with­out ever mak­ing a de­ci­sion. In par­tic­u­lar, be care­ful about con­fir­ma­tion bias, where you search for any piece of in­for­ma­tion that con­firms what you want to be­lieve. If the weather is be­low ap­proach min­i­mums at all three air­ports near your des­ti­na­tion, don't keep search­ing un­til you find one good metar. That’s false hope, and it’s dan­ger­ous.

It takes prac­tice, but the goal should be to re­view enough data to have a com­plete picture of the weather in front of you, but with­out get­ting mired in the weeds.

3. Watch the time stamp. Here’s your re­quired warn­ing about the de­layed na­ture of datalink weather. Yes, that radar im­age could be any­where from five to 20 min­utes old, and a lot can change in a thun­der­storm in that time. Care­fully watch the time stamp on the app or MFD to make sure you’re get­ting cur­rent weather, and re­mem­ber that “four-minute-old” radar only means the re­ceiver got that in­for­ma­tion four min­utes ago — it could ac­tu­ally be 10 or 15 min­utes since the radar sweep.

That’s why the oft-re­peated advice to use datalink weather for strate­gic avoid­ance in­stead of tac­ti­cal pen­e­tra­tion is smart. But there’s more to it than that. If you have a good idea of the big picture, it’s easier to fit chang­ing weather re­ports into your men­tal model. Is that storm build­ing rapidly be­cause of a fast-mov­ing cold front or be­cause it’s a hot sum­mer day with un­sta­ble air? An­other tac­tic is to an­i­mate the weather charts (if pos­si­ble) to see any trends. Of­ten, the di­rec­tion and speed of change mat­ter as much as the spe­cific im­agery. 4. Make big de­vi­a­tions early on, and change flight plans. The ob­vi­ous les­son from the pre­vi­ous tip is to avoid se­vere weather by a wide mar­gin. That re­quires a change in mind­set for many pi­lots. With datalink weather on board, I spend a lot less time fly­ing up to weather and then ask­ing for “10 de­grees left, 20 de­grees right” as I pick around cells. In­stead, I look at the weather map and change the route of flight 50 miles ahead of time: “Re­quest­ing di­rect Boiler VOR, Victor 97, Chicago Heights to avoid weather.” This might add four min­utes to the flight, but it pro­vides a mar­gin of safety, traf­fic con­trol (since they can en­ter it into their com­puter and pass your new route along to the next sec­tor).

5. Your eyes get a veto. The best weather sen­sor in any air­plane is an ob­ser­vant pi­lot’s eyes, backed up by datalink weather, not the other way around. In the end, weather avoid­ance in light air­planes is very much a vis­ual process — even when fly­ing IFR. In­stru­ment pi­lots can and should fly through clouds, but the best strat­egy is to stay vis­ual as much as pos­si­ble and avoid nasty-look­ing clouds. Never let an iPad screen talk you into fly­ing through weather that your eyes don’t feel com­fort­able with. I’ve de­vi­ated around plenty of buildups that were not show­ing up on the radar yet sim­ply be­cause they looked omi­nous to me.

No mat­ter how many hours you’ve logged, weather is a chal­lenge. Un­like in­stru­ment ap­proaches, which are static and re­ward rote prac­tice, weather is con­stantly chang­ing and de­mands nu­anced de­ci­sion-mak­ing skills. We must ap­proach every flight with a flex­i­ble mind­set and be dis­ci­plined enough to play the hand that Mother Na­ture deals us. She does not care about the fore­cast, so the only sure thing is the late Richard Collins’ first rule of weather fly­ing: “What you see is what you get.”

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