The Myth (Almost) Of Tailwinds

Mooney was ready to pull the plug on the project, and I was advised the new TLS would need to return to Kerrville for sale if I couldn't set the records by April 1. Finally, on March 24, my luck changed. A fast-moving cold front had raged through Southern California the night before, and I caught the tail of it the following morning for a fast ride across the country.

I launched out of Long Beach, got a vector over the Pacific off LAX, climbed to FL250 and ripped back across LAX VOR with a groundspeed well above 300 knots, the result of roughly 80 knots of tailwind.

The first record, from LAX to Albuquerque, scored 294 knots. The second, the cumulative leg from LAX to Dallas, logged a speed of 283 knots, and the segment from Dallas to Jacksonville recorded a still respectable 260 knots. The overall average record speed from Los Angeles to Jacksonville worked out to 261 knots, just over 300 mph. That included a superfast descent and landing at Dallas Love for fuel and sandwiches.

With the successful Los Angeles--Jacksonville flights, the American NAA and the International FAI granted me four city-to-city speed records in weight class C1B, and four more in the unlimited class. Since 1994, I've added 20 more international speed records to places as diverse as Iqaluit, Nunavut, Canada; Kulusuk, Greenland; Reykjavik, Iceland; and Edinburgh, U.K.

Many of those records were flown with the benefit of tailwinds, a not-so-simple matter of waiting for the right conditions before launching; picking the optimum altitude for best speed and the most efficient method of climb; minimizing aircraft weight and flying with the CG close to the aft limit; reducing drag as much as possible; and calculating the fastest method of descending at the destination. Fortunately, city-to-city records don't require a two-way effort. (In contrast, seekers of ultimate speed records must complete a two-way run above a 3 km course, specifically to nullify any benefit from the wind. In 1989, when Lyle Shelton tried for the world prop/piston speed record in Las Vegas, N.M., he made two two-way runs in his modified Grumman F8F Bearcat, Rare Bear, averaging 528.3 mph to obliterate the previous record by nearly 30 mph.)

Trouble is, tailwinds are more fickle than you might imagine. In the real world of business and personal travel, most pilots don't have the option of waiting for perfect conditions to make their trips. Perhaps for that very reason, the uninitiated might expect the laws of probability to produce headwinds and tailwinds with roughly the same frequency, effectively canceling each other out.

Unfortunately, there are a number of reasons why that's not normally the case. The dominant wind pattern across the U.S. is west to east. That might imply you'll break even if you fly an out-and-back horizontally across the country.

Even if that were true (which it isn't), simple math suggests that headwinds act on an airplane longer than tailwinds, so you'll always lose time in any consistent headwind/tailwind situation. A 100-knot airplane flying into a 20-knot headwind will require 2+30 to complete a 200 nm trip. Turn the airplane around, and the return trip will demand 1+40. That's 4+10 for the round-trip. In no-wind conditions, the same airplane will demand only 4+00 for the round-trip, so you're better off with no wind at all than with a tailwind. In order to break even on the return flight, you'd need to increase the tailwind to 33 knots. (The situation deteriorates even further as the wind increases in strength. With the scenario above, a 50-knot, direct head-/tailwind results in a total flight time of 5+20 compared to 4+00 in no-wind conditions.)

One standard trick to avoid losing speed to winds is to fly the tailwind leg as high as possible, where the wind is strongest with minimal influence from the topography below, then make the return trip as low as feasible to operate in the least headwind.

Trouble is, that won't work everywhere. There may be geographical factors that tend to work against you in flying high/low. Folks aviating out West, where mountains interrupt the horizon, may need to fly high on both legs. The high/low trick can work well in the Midwest, where it's easy to be convinced the earth truly is flat, but it may not be viable over the Rockies or Sierra Nevadas.

Then, too, pilots who've been flying for a few years know that any consistent wind from any direction on a round-trip always costs you speed. A direct, 90-degree crosswind of any velocity will always subtract a knot or two from groundspeed, and you won't begin to realize any advantage from a tailwind until it's at least five degrees behind you. That means you start off with a 10-degree disadvantage. Score: wind 190, pilot 170.

Similarly, strong winds often make the ride rougher, and that means less efficient. While it's certainly possible to find tailwinds that will whisk you to your destination with a ride as smooth as a pool table, the cobblestone road is more often the case when the wind is brisk. Turbulence of any kind always costs you speed, more on some airfoils than on others, so smooth air with minimal wind allows a wing to operate with maximum efficiency.

In an age of XM weather and GPS direct flight plans, the tendency is to punch up the destination identifier and fly the resulting course line. That will work, but don't be too quick to blindly follow the GPS mantra of direct-to.

For some pilots, there may be a better method, and it's called pressure-pattern flying. This can be a partial solution to unfavorable winds, but it's usually reserved only for high-Mach aircraft flying long distances. It doesn't work well on short hops, because weather systems are too large and far apart to impart any benefits over short legs.

If you're traveling coast to coast in a modestly fast airplane, you might consider selecting a route that logs more miles but provides you with better winds; then, pull the same trick and choose a more favorable route for the return. Airlines and other operators of long-range turbine equipment sometimes employ this technique to reduce en route time. After all, time, not distance, is all that matters, and the airlines are masters of that equation. (Remember that the next time you fly from San Francisco to Orlando by way of Boston.)

When I fly Pacific deliveries from the mainland, the average wind component on the first leg to Hawaii nearly always is negative, usually minus-2 to minus-8 or so. (Any worse than that, and I'll usually wait another day or two for more favorable winds.) One way I can sometimes turn the flow to my advantage is by checking wind patterns farther up the coast to see if I'm better off flying north sooner in the trip.

I'm based in Southern California, so I typically start off from Santa Barbara with direct headwinds, then watch the wind gradually shift around clockwise to the tail about 1,200 nm out. If I can expedite that shift a few hundred miles sooner, then it might be smart to depart farther north along the California coast or route slightly north of a great circle to Hilo or Honolulu.

In fact, no matter how long the leg, you can help alleviate the effect of headwinds or take advantage of tailwinds from the moment you leave the ground. If I'm in a turbine and climbing into headwinds, I'll sometimes use a cruise climb to allow me better forward speed. If the winds are going my way, I'll use a slower, near-Vy climb to gain maximum altitude as quickly as possible.

At the opposite end of the flight, I'll maintain height as long as possible in strong tailwinds, then descend at a high rate. I'll reduce altitude more leisurely in headwinds. The advantage may be small, but with turbines or even a big piston single, a few minutes saved can be a significant advantage.

Make no mistake about it, tailwinds do exist, though they're rarely available when and where you want them, and they're almost never as strong as forecast. An old-time ferry pilot (probably named Murphy) once imparted a rule I find helpful and more accurate than the weatherman's best guess. Cut any forecast tailwinds in half and add at least half to any predicted headwinds. It usually works for me.