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.

Crosswind Takeoffs and Landings

Even with a brisk crosswind blowing across the runway, many pilots are reluctant (or neglect) to use all of the available flight controls during crosswind takeoffs and landings.

As the FAA Airplane Flying Handbook explains:

The technique used during the initial takeoff roll in a crosswind is generally the same as the technique used in a normal takeoff roll, except that the pilot must apply aileron pressure into the crosswind. This raises the aileron on the upwind wing, imposing a downward force on the wing to counteract the lifting force of the crosswind; and thus preventing the wing from rising…

While taxiing into takeoff position, it is essential that the pilot check the windsock and other wind direction indicators for the presence of a crosswind. If a crosswind is present, the pilot should apply full aileron pressure into the wind while beginning the takeoff roll. The pilot should maintain this control position, as the airplane accelerates, and until the ailerons become effective in maneuvering the airplane about its longitudinal axis. As the ailerons become effective, the pilot will feel an increase in pressure on the aileron control. (6-6)

Here’s a short video that shows this technique in action. During a recent coast-to-coast flight in my Beechcraft A36 Bonanza, I departed Portland, ME (KPWM) with a strong crosswind from the right.

The goal while landing, as described in the FAA Private Pilot ACS is to:

Touch down at a proper pitch attitude with minimum sink rate, no side drift, and with the airplane’s longitudinal axis aligned with the center of the runway. (Task IV. Takeoffs, Landings, and Go-Arounds)

When landing with a crosswind, you must also apply and hold aileron inputs into the wind while using rudder and elevator pressures to track the centerline, keep the aircraft aligned with the runway, and touch down in the proper pitch attitude.

Here are two short videos from the same trip that show this technique in action, first at Bradford, PA (KBFD) and then at Nashua, NH (KASH).

Another Cross-Country in the A36

In May 2022 I flew the Beechcraft A36 from Seattle (KBFI) to New Hampshire (KASH) again for for IFR Mastery sessions at Pilot Workshops. The round trip of 4956 nm required 35.1 hours of Hobbs time and included a few days waiting out weather in Wisconsin, both eastbound and westbound.

To see videos from the trip, visit the Coast-to-Coast May 2022 playlist at my YouTube channel, BruceAirFlying. The video below is from a low-level flight along the Chicago skyline as I flew from Oshkosh, WI to Valpariso, IN.

Yoke Mount for iPad Mini

When I fly the A36 Bonanza, I mount my iPad Mini on the yoke using a RAM X-Grip with the large strap hose clamp and ball and a short RAM arm to connect the clamp to the X-Grip.

This arrangement works with 1984 and later Beechcraft Bonanzas and Barons, which use conventional yokes, not the big crossbar or throw-over yokes installed in earlier models. The tube that connects the Beechcraft yokes to the mechanisms behind the panel has a larger diameter than the tube used in other aircraft, such as Cessnas, so the large strap hose clamp is necessary to secure the mount.

The X-Grip holds an iPad securely while allowing air to circulate around the tablet, reducing the likelihood that it will overheat in flight. The X-Grip works even when an iPad is in a low-profile case. But it might not hold a tablet that is in a heavier, bulkier case.

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).

Unusual Attitudes: Under the Hood

AOPA has been putting the former BruceAir Extra 300L to good use. Here’s a video that shows how the Garmin GI-275s that they installed perform during a series of unusual attitude recoveries with the pilot flying “under the hood”–unable to use outside visual references.

Takeoff and Landing Performance

Here’s a trick question: How do you how much runway you’ll need to take off today?

The gotcha answer: You don’t know. The best you can do is estimate performance based on the available data and then add a conservative safety factor.

Pilot Workshops recently posted a Tip of the Week about aircraft performance. You can find it here. (Full disclosure, I participate in the IFR Mastery series at Pilot Workshops, and I occasionally contribute tips of the week).

During stage checks at the flight school where I instruct, we ask pilots to calculate and explain takeoff and landing performance. When I review their numbers, I always ask about the assumptions behind the numbers. The discussion that follows typically goes something like this:

First, note that for most light aircraft, the POH/AFM includes takeoff and landing numbers only for short-field operations. You don’t typically find “normal” takeoff and landing data.

So the values you calculate based on the tables or charts assume setting the flaps as specified, running the engine up to takeoff power while you hold brakes, raising the nose at the specified airspeed, etc.

Is that how you typically take off?

The performance data also assume a new engine that produces rated horsepower, but none of us knows if our engine, today, is achieving that number.

Now, let’s do some basic arithmetic. The book for a C172S says that at sea level on a 20 C day, the ground run at 2550 lbs. takeoff weight is 995 ft. Call it 1000 ft. Distance to clear a standard 50 ft. FAA tree is 1690 ft. Again, assuming precise short-field technique.

Knowing the above, most pilots tell me they’d add 10 or 15 percent to those numbers as a buffer. But 10 percent of that 1000-ground roll is 100 ft. Ten percent of 1690 (call it 1700) is 170 ft.

The C172 takeoff table assumes liftoff at 51 KIAS (86 ft/sec) and 56 KIAS (95 ft/sec) at 50 ft. In other words, as you lift off and climb out, you’re covering about 100 ft/sec. In three seconds (“one-potato, two-potato…”), you fly the length of a football field (or soccer pitch). Have you watched runway stripes go by as you try to urge the airplane aloft or float a bit on landing? Runway stripes are typically 120 ft long, with 80 ft gaps between them (minimum stripe length is 80 ft).

Similar considerations apply when you estimate how much distance you’ll need to land.

These numbers are one reason that I recommend viewing REALITY CHECK: TAKEOFF AND LANDING PERFORMANCE from the AOPA Air Safety Institute and then following the long-standing AOPA ASI advice to multiply your takeoff/landing calculations by at least 1.5.

And for a more detailed discussion of aircraft performance, see Performance: What Matters Most by Catherine Cavagnaro in the July 2021 issue of AOPA Pilot magazine.

AviationWeather.gov Updates

The National Weather Service is overhauling the AviationWeather.gov website. You can preview the new look at: https://beta.aviationweather.gov/

The new site is still in the experimental stage, but many of the changes look promising. According to a tweet from the NWS:

AWC’s web developers have been working on a major upgrade for http://aviationweather.gov. New features include automatic screen resizing (looks great on cell phones), dark/night mode, and an archive.

Flying the Blake Arrival at Boeing Field

Ride along as I return to Boeing Field (KBFI) after a quick stop for fuel at the Shelton-Sanderson airport (KSHN), southwest of Seattle.

I set up for the Blake Arrival, a VFR procedure that begins over Blake Island, which lies about 8 miles west of Boeing Field.

The VFR departure and arrival routes for Boeing Field are described on the reverse side of the Seattle terminal area chart, the so-called VFR Flyway Planning Chart.

I have created more detailed descriptions of each departure and arrival route, available as a PDF in my Aviation Documents folder at OneDrive.

The Blake Island Arrival is a “south arrival” for traffic inbound from the west. It’s used when Runways 14L and 14R are active. It begins over Blake Island at 2000-2500 ft to remain below the Class B shelf in the area. You then fly direct toward Lincoln Park, just north of the Fauntleroy Ferry dock, descending to cross the shoreline at 1500 ft, then continuing down to 1000 ft, taking care to remain below and clear of the overlying Class B airspace.

Boeing Tower usually directs you to fly a right base leg for runway 14R, but sometimes, to sequence you with other traffic, ATC needs to put you on a right downwind.

Or, as happened on this day, changes your runway assignment to 14L.