Waypoints: When the wind blows

A December trip to Sparta, Tennessee’s Upper Cumberland Regional Airport and back the next day showed the dramatic effect wind can have on a light airplane. Three hours and 52 minutes there. Just two hours and 33 minutes home less than 24 hours later. The no-wind trip should have been about two hours and 45 minutes. Instead, brutal headwinds drove typical cruise speeds in my Bonanza of more than 160 knots true airspeed down to as low as 97 knots groundspeed, but mostly to less than 120 knots. Add in passage through a cold front with plenty of precipitation, temperatures just north of freezing, turbulence from the Appalachian Mountains, and darkness for the final portion, and it was a veritable weather buffet. After almost four hours we were glad to touch down on Sparta’s long runway.

The next afternoon delivered a much more pleasant flight home, with tailwinds and relatively smooth cruising over an undercast. The lowest groundspeed I saw in level flight was 167 knots; highest, 205 knots. However, in the “not fair” department, the typical push was about 17 knots versus the typical headwind the day before of around 40 knots. Is there a place where we can file such complaints?

A January trip to Knoxville proved to be almost as challenging. What should have been a no-wind two-hour-and-24-minute flight required three hours and 39 minutes. Coming home the next morning we shaved an hour and 20 minutes off the trip, with only a few knots of tailwind. The trip to Knoxville, though, proved particularly interesting because of mountain waves. The Appalachians, for all the taller they are, produce prodigious mountain waves. This trip I decided not to battle them so much and asked air traffic control for a block altitude from 6,000 to 8,000 feet msl. Later, tops of an undercast grew to meet us even at 8,000, so I asked for a block between 8,000 and 10,000 feet. ATC helpfully agreed. I left the autopilot in Nav mode, but kicked off the altitude hold and managed the vertical component by hand. The result was a much more pleasant ride with the airplane drifting up and down at the whim of the waves.

The website FlightAware.com allows you to track flights in great detail, including minute-by-minute reports of location, direction, speed, rate of climb or descent, and altitude. For the Knoxville flight, FlightAware shows a lot more updrafts than downdrafts, especially for the initial period as we bounced around between 6,000 and 8,000. Rates of ascent were frequently at or near 600 fpm, while the greatest rate of descent was 400 fpm, and most were much less. Between 8,000 and 10,000 feet the rates of change were more gradual, but the winds picked up. At one point our groundspeed dropped to 64 knots, but five minutes later it was at 100 knots, according to the website.

A week or so later, I was south-southwest bound to Florida with winds from the west at a similar 35 to 45 knots. However, because of the more southerly course, the headwind component was small, making my groundspeed and true airspeed almost match. In fact, I picked up a tailwind once we hit Florida.

So what’s the lesson here? Don’t fly westbound in the winter! OK, that may not be practical. But do be aware of the actual winds, especially on long winter flights. On both of the Tennessee trips, the winds were stronger than forecast. En route to Sparta, a couple times when the winds were particularly strong, I was looking at refueling options along the way. In the end I landed with nearly 90 minutes of fuel, but looking at it minute by minute on the fuel computer, I was not so certain I could make the intended destination with my desired 60 minutes of fuel in the tanks.

Finally, use the tools you have available. I am fortunate to have an air data computer in my Garmin G500 that shows me a continuous readout of the actual wind speed and direction, as well as a separate presentation of the wind component. That, combined with a GPS and a fuel computer, allowed me to know with great detail my options. Leverage ATC for ride and wind information from other aircraft. Sometimes changing altitude by a few thousand feet can make a significant difference in wind speed and direction. Use your head. Light airplanes are just that. We are no match for severe turbulence, icing, and in this spring season, thunderstorms—so if you have doubts, stay on the ground. The mantra: “I’d rather be on the ground wishing I were flying than in the air wishing I were on the ground” is something to live by.

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