Reeling In Rough Air

As a student pilot, I recall flying on my own to the familiar rural airport where I had first soloed to hone my soft- and short-field skills. After proving to myself that I had those maneuvers down pat, I realized I still had about 30 minutes left until I needed to head back to my home airport.  

It was a hot summer day in Central Texas and an absolute sauna in the cockpit of my Skyhawk. As such, I decided to climb to more comfortable temperatures for a steep turn rehearsal.

At TL027 (my cheeky notation for Temperature Level 27C), I performed clearing turns and a steep turn to the left, flying through my prop wash upon completion. I patted myself on the back for nailing the turn in bumpy conditions and began rolling into a right steep turn.  

WHAM!

Apparently, sledgehammers were falling from the sky, and one had hit my airplane, sending me sharply downward. In response, I pulled hard on the yoke and simultaneously experienced a vertical gust from below—or so I thought. 

Flying back home, I experienced more of the same aggressive turbulence, fighting to maintain at or below 2,000 feet per ATC’s instructions. After explaining this scenario to my CFI, he grinned and told me how I had worsened it. While the air caused half the sudden, jarring changes in altitude, the PIC caused the other half. Oops.

In theory, we all know how to fly in turbulence: Slow to Va and focus on maintaining attitude instead of altitude. But keep in mind that mitigation and avoidance are important elements of dealing with turbulence, especially if you’re carrying nervous passengers in your GA airplane. The turbulence experienced in an SR-22 may be frightening to non-pilot passengers compared to the Airbus A320 turbulence they’re used to.

Here are some insights and mitigation and avoidance tips when considering turbulence.

Turbulence ≠ shear
Turbulence is annoying but rarely dangerous. Shear can bring you out of the sky. Brief wind conditions and forecasts along your route before taking flight, and continue monitoring them during flight. We mostly avoid turbulence for comfort but must avoid shear for safety.

Know what Va actually is
As a refresher, Va is the speed at and below which the airplane will stall before its limit load factor can be exceeded. It’s listed in the POH for your aircraft in the Limitations section and is the speed at or below which you should maintain in turbulent conditions.  

Know what Va is at different weights
Depending on the make and model, the POH may list several Va speeds based on weight. For example, in the Cessna 172R POH, calibrated and indicated Va speeds are listed based on three different gross weights. 

If you’re loaded to the gills at 2,450 pounds gross, Va is 99 knots indicated. But, if you’re just a couple of passengers lighter at 2,000 pounds gross, the indicated airspeed for Va is lower at 92 knots. 

However, some POHs only list Va at gross weight. If that’s the case and you’re not flying at gross, you can still figure it out. Per Barry Schiff, “Va for lighter weights can be approximated by reducing the published Va by two knots for each 100-pound reduction in gross weight.” As with all performance calculations, err toward conservative (slower) numbers, and remember that you’re losing the weight of burned fuel as you fly.

Weight is great
The heavier you are, the harder it is for turbulence to push you around (refer to the aforementioned SR-22 vs A320 comparison). The greater mass of a planeload full of bodybuilders and 100LL won’t be pushed as far as the solo marathon runner flying with ⅓ tanks. 

Imagine kicking a beachball that weighs only a few ounces, then imagine kicking a 14-pound bowling ball with the same force. The ball is your airplane, and your foot is the wind. The bowling ball won’t move nearly as far. Also, don’t kick a bowling ball. It hurts.

Turbulence is born of contrast
Lighter ground or water next to darker ground can create a sharp temperature gradient by radiating heat at different rates, disturbing the air above it. Hills and mountains direct air such that it changes direction and speed and can cause rotary air movement. 

Temperature and pressure differences between large air masses breed turbulence at and around their intersections. When planning and performing a flight, stay mindful of permanent turbulence makers, like geographic features, and more transient causes, such as frontal boundaries.

Do as I say, not as I did
As a solo student pilot flying through rough air on that sultry summer day, I had not fully absorbed the best practice of flying with fingertips on the yoke and focusing on maintaining attitude as opposed to altitude. My neophytic reactions made my ride twice as wild as it had to be. 

So, the final pointer is to remember to employ the classic rules we all know: use a light touch on the controls to maintain attitude as opposed to altitude, and slow to the Va speed you calculated before your flight.

Know Before You Go