I Survived a Downwind Turn

One of the most persistent misconceptions in aviation is that so-called downwind turns are dangerous. Proponents of this fallacy typically present the following basic argument:

Consider an airplane flying due north at, say, 100 KIAS into a 30 knot direct headwind. The airplane’s groundspeed is therefore 70 knots. If the airplane, still flying at an indicated airspeed of 100 knots, turns 180 degrees to a heading of due south, it needs to “gain” 60 knots to match its new groundspeed of 130 knots—that is, the sum of its airspeed and the wind velocity. A pilot who doesn’t take care to add power or push the nose down to help the airplane “gain energy” in the turn risks stalling and falling out the sky.

That argument may seem logical and consistent, but it doesn’t hold up when we actually do the experiment, as you can see in the video below.

I took advantage of an IFR training flight with a student in a C172 to capture the “downwind turn” phenomenon in action. We had flown an instrument approach and then climbed to 4000 ft to enter and fly the published hold at CARRO intersection, a fix located 24 nm southwest of the SEA VOR.

The track data shows that as we flew the outbound leg of the hold, we were cruising at about 100 KIAS almost directly into a wind of about 30 knots.

When we turned 180 degrees back inbound to CARRO, our airspeed remained essentially constant (the student was hand-flying the aircraft, which doesn’t have an autopilot).

Our groundspeed varied from about 80 knots outbound to some 120 knots on the inbound leg. But the pilot didn’t have to add power—or do anything else out of the ordinary—to keep the airplane flying. He just turned as if we were flying on a dead calm day. Because from the airplane’s perspective in the air, the 30-knot wind aloft didn’t exist.

And without looking outside at the ground or checking the groundspeed and wind displays on the PFD, we wouldn’t have sensed the wind, either.

We gained groundspeed thanks to the push from the wind.

As many experts have tried patiently to point out, the key to this situation is knowing that velocity and energy are measured with respect to specific frames of reference.

For example, the kinetic energy of an airplane that concerns us during takeoff, landing, and cruising to our destination—or when crashing into terrain—is a function of groundspeed, which is measured with respect to the earth.

If you are flying at, say, 60 KIAS in zero wind, when your wheels touch the runway you have the kinetic energy associated with 60 knots groundspeed and the aircraft’s mass.

Touch down at, say 60 KIAS into a 20 knot headwind, however, and you have the kinetic energy associated with a velocity of 40 knots, with respect to the earth.

But in both of those situations, your speed through the air remains 60 knots.

As the following excerpt from a column in AOPA Pilot by Catherine Cavagnaro succinctly explains, changes in the aircraft’s kinetic energy with respect to the ground are powered by the wind, and the change in groundspeed applies regardless of the aircraft’s mass or power, because the aircraft is always moving within and along with the air mass in which it is flying, just like a leaf, or a branch, or a boat floating downstream in a river.

A baseball that hits a wall gains no energy in the process. But when it hits a fast-swinging bat, it gains a significant amount before it soars toward the outfield. In the flight scenario, the airplane plays the role of the ball and the wind is the swinging bat. Without wind there is no change in energy from the departure leg to the downwind leg. But the 20-knot wind supplies the extra energy that increases the groundspeed of the airplane. It’s the same energy increase we enjoy as we travel cross-country with a strong tailwind. To avoid a stall in any turn, take the same precautions one does in an ordinary no-wind situation. (Proficiency: Relax and Go With The Flow, AOPA Pilot, August 1, 2019, by Catherine Cavagnaro)

In the air, your energy with respect to the airmass remains the same, regardless of which direction you fly and the presence of wind, if any. You can maneuver at will, and at a given airspeed, the airplane’s kinetic energy with respect to the airmass, regardless of the wind direction, doesn’t change. And when considering stall speeds, your airspeed (actually, angle of attack) measured with respect to the airmass is all that matters—because that velocity is what the wing experiences.

Of course, wind shear—an abrupt change in wind direction and/or speed—and vertical gusts–does affect an airplane. Those phenomena cause variations in angle of attack and G loads. But the myth of the downwind turn isn’t about wind shear. It’s an error caused by conflating frames of reference.

For more information about this topic, see the following articles and other videos:

And for a wonderful presentation about frames of reference and the fundamental principle of relatively (not limited to Einstein), see: Relativity Crash Course by Ramamurti Shankar, a professor of physics at Yale University.

A Gusty Crosswind Landing at KBFD

I have been flying the A36 Bonanza on another coast-to-coast trek to work with the crew at Pilot Workshops. On such long xc flights, you often must deal with challenging conditions, and such was the case when I landed at Bradford, PA (KBFD) for fuel (video below). I had been flying directly into strong headwinds the entire day (unusual when traveling eastbound) as I tracked just north of a strong low-pressure system.

The gusty, shifting winds at KBFD were generally 30-40 degrees off any of the available runways, so with the help of the information in ForeFlight, I chose runway 14 and wrestled my way to the ground.

The wide, sturdy landing gear of the Bonanza handles crosswinds well (the max demonstrated xwind component is 17 knots).

A Low IFR Approach at KOLM

After a long stretch of widespread fog and icy clouds, the skies in the Puget Sound area cleared—mostly—creating a good opportunity to fly an instrument approach in LIFR conditions at Olympia, the state capital southwest of Seattle.

Ride along in this video at my YouTube channel as I make the short hop in the A36 Bonanza from Boeing Field to fly the RNAV (GPS) RWY 17 approach at KOLM.

The approach offers LPV minimums to the same 200 ft DA and ½ mile visibility as the ILS, and I broke out only a couple of hundred feet above the decision altitude.

The sophisticated avionics and Garmin GFC 600 autopilot in the Bonanza make it easy to fly such approaches. But the skies were busy with training flights, and ATC had its hands full. As you’ll see, one confusing instruction from Seattle Approach had me scratching my head until the controller and I got on the same page.

ILS at Boeing Field (KBFI)

After flying a low approach almost to minimums at Bremerton (KPWT), I made the quick return to Boeing Field (KBFI) via radar vectors to the ILS RWY 14R, where the weather was better, with a ceiling of about 1000 ft. and good visibility below the clouds. As you’ll see, it’s a moderately busy flight given the short distance and the usual challenge of fitting into the flow at KBFI.

On this late-November afternoon, however, I enjoyed the rare treat of cloud surfing above a solid undercast, with blue skies above, at least for a few minutes. Keen observers will even spot Mt. Baker in the distance as I turn northeast.

For more information about the technique of setting a course to a fix, which I often use when flying the ILS at KBFI, see Setting a Course v. Vectors to Final. To learn about annotating electronic IFR charts, see Annotating IFR Charts.

A Visual View of an Instrument Approach

I always have instrument students fly their first approaches in visual conditions so that they can see how the displays in the cockpit correspond to the view outside.

Ride along as I fly an RNAV (GPS) approach at Hoquiam, WA (KHQM), and observe how close you come to terrain and other obstacles while following the lateral and vertical guidance, and how, in this case, the autopilot maintains a steady track as it compensates for shifting winds.

This video focuses on the cockpit displays and the view from the camera on the right wingtip. I flew this approach in VMC, and I haven’t included ATC communications or general cockpit views.

You’ll also notice that I mark up charts to help me note important details during preflight planning and to guide me through procedure briefings in the cockpit.

You can learn more about my method for annotating electronic charts in a separate video on my YouTube channel. I also have a video about briefing IFR procedures.

Twighlight Takeoff

A nice twilight view of a takeoff from runway 32L at Boeing Field (KBFI) in Seattle. I was headed out to log night takeoffs and landings at Arlington, WA (KAWO), north of Seattle. Although runways 14 were in use, the tower offered an opposite-direction departure from runway 32L to speed my on my way.

As I depart, you can see a “string of pearls,” the lights of airliners inbound to land on runways 16 at Seattle-Tacoma International Airport (KSEA).

An ILS at Night

Clear skies recently offered an opportunity to log a little night flying time and to practice an ILS at Boeing Field (KBFI). I can’t log the approach for IFR currency (I wasn’t under the hood and didn’t have a safety pilot), but it’s still good practice to fly approaches in VMC when possible to reinforce IFR procedures.

An RNAV Approach at Walla Walla

Here’s video of the RNAV (GPS) RWY 20 approach at Walla Walla, WA (KALW). Because my A36 Bonanza is equipped with WAAS-capable Garmin GTN 750, I can fly to the ILS-like LPV (localizer performance with vertical guidance) minimums. Given the choice between an ILS and an RNAV procedure with LPV minimums, I usually choose the RNAV approach. It’s easier to set up with no CDI switching required.

Aerobatics with Data

Here’s a look at an aerobatic ride with data from a Garmin VIRB Ultra 30 camera’s sensors overlaid. The GPS-based position, speed, and altitude don’t match the information from cockpit instruments precisely, and the sensors sometimes can’t keep up with the dynamics of aerobatics, but the data do give you an idea of how quickly things change during aerobatics. We also had a tailwind of about 6 knots during the landing, so the GPS-derived groundspeed is higher than the indicated airspeed during the approach and landing.

It’s also worth noting that during aerobatic rides I try to fly smoothly and keep the Gs under control. Rides aren’t aerobatic contests or airshows.

To display the data in a video, I first import the video and corresponding data into the free Garmin VIRB Edit program. After choosing the gauges to display, I export the video and do the final editing in Adobe Premiere Elements.