An email I received recently concluded with a one-word expression of good wishes: “Tailwinds.”
Pilots love tailwinds. They speed us to our destination, so we scan winds-aloft forecasts for cruise altitudes where we can find them or most efficiently exploit their effects.
Don’t let your tenderness for tailwinds tempt you to take off or touch down with one. When groundspeed exceeds airspeed, it can pose problems beyond the obvious hazard of increasing the amount of runway you’ll consume.
A more pronounced, but less obvious, hazard is losing directional control, either before there’s enough lift for flight on takeoff, or after touchdown on landings. In those high-groundspeed, low-aerodynamic-control scenarios you could skitter off the side of the runway before you have time to recover.
Reviewing the takeoff and landing performance charts in the pilot’s operating handbook for your aircraft lets you figure runway consumption under headwind and tailwind conditions. According to the short-field landing performance chart for a Cessna 1978 172N, you would increase published distances “by 10 [percent] for each 2 knots” of tailwind up to 10 knots. (Does a short-field landing with a tailwind strike you as ill-advised? Accident investigators include such pilot decision-making when determining probable causes of mishaps.)
Some pilots who fly from long runways dismiss the risks of operating in tailwinds—but a long runway doesn’t solve the directional control dilemma.
Once in a while a tailwind landing is necessary, as the pilot of a Van’s Aircraft RV–12 discovered after experiencing an engine failure on takeoff.
The pilot made it back to the runway, “but with an airspeed of 65 Knots (best glide) and a gusting tailwind, my groundspeed back to land was excessive and contributed to my lack of control on landing,” the pilot wrote in a filing with the Aviation Safety Reporting System, explaining why the airplane ran off the side of the runway and struck a taxiway sign.
If the foregoing turns you off from tapping “Tailwinds” as the signoff for your aviation emails, the ever-popular “Blue skies” makes a cheery alternative.