Human Factors: The wind at your back is for sailors

The official records don’t say why the 71-year-old private pilot was making the flight from Falmouth, Kentucky, to Spruce Pine, North Carolina.

Maybe he was planning to grab lunch at Famous Louise’s Rock House Restaurant, only three miles from Avery County/Morrison Field (7A8), or maybe he was headed for a few days at the Springmaid Mountain Resort.

But we do know that the solo flight was uneventful, and that before he departed — as he’d never been to 7A8 before — he called the FBO and “was informed that best practice was to land uphill on 33 and take off southbound downhill on 15,” due to the slope of the runway.

He also checked weather with flight service before departing.

He did not, however, bother to check the wind on his arrival before setting up to land.

I bet you just heard the first link in the accident chain clink solidly into place.

The Accident

The pilot spirals down to pattern altitude from 7,500 feet in his new-to-him 1964 Beech A-23 Musketeer, joins the pattern, and sets up for final approach at 80 knots on the preferred uphill Runway 33, using his usual one notch of flaps, and then…the runway just keeps passing by under his wings. He dumps all the flaps, but the float continues.

The airplane finally settles to earth with only 200 feet of the 3,001-foot runway remaining in front of the Musketeer’s bright orange spinner.

The pilot slams on the brakes, but energy wins the day. The airplane exits the runway, crosses the 170-foot long overrun at the teacup, travels across a short grassy area, plows through the perimeter fence, travels down a small embankment, and finally comes to rest on State Road 1101, blocking the eastbound lane.

Both the pilot and the airplane suffer broken noses. The airplane’s is more serious — it is later sold for scrap.

As the dust settles, and the pilot crawls from the wreckage, it dawns on him that he might have had a tailwind.

He later tells an NTSB investigator, “I believe a tailwind was pushing me,” and in his report of the accident to the NTSB he wrote, “My error was not checking the wind direction.”

The Pilot

The private pilot had 500 hours in his logbook. He purchased the Musketeer a little over a month before the accident, and while he had 35 hours in the make and model, he had only flown his new ride for 10 hours, two-and-a-half of them the day of the airplane’s final flight. He was due for his flight review the following month.

The NTSB

The NTSB’s final word on the cause of the accident is: “The pilot’s failure to familiarize himself with the wind conditions at the destination airport and his failure to attain the proper touchdown point during landing, which resulted in a long, tailwind landing and subsequent runway overrun.”

Analysis & Discussion

On one hand, the pilot showed good judgment in calling the locals for intel before flying into a new-to-him airfield.

But why didn’t he check the wind on his arrival?

The answer to that might be found in his discussion with the investigator from the NTSB, who said the pilot told him, “I should not have assumed just because I was told to land northward, because it is upsloping, that that was the right way to land.”

That’s an interesting statement that we can all learn from. 7A8 is an uncontrolled airport, so no one can “tell” any of us what to do there. But in learning the recommended procedure for the slope, did the pilot somehow translate that information into a mandatory instruction?

Or perhaps he was the victim of plan bias. He knew the preferred procedure and planned to use it. Did his plan place blinders around his eyes and mind?

But to the point of not checking the wind?

Now, 7A8 does not have a weather robot, and the nearest is at Foothills Regional Airport (KMRN), more than 20 miles east in Morganton, N.C., worthless information given the terrain difference between the two.

Foothills is the airport the NTSB used, as its investigators had nothing else, but the field is out on the flatland northwest of Charlotte, while 7A8 is tucked up way into the Blue Ridge Mountains, so we can’t say with any degree of certainty what the wind was actually doing that day.

But 7A8 does have a windsock. You can even see it on Google Earth, much less from the traffic pattern, so there’s no excuse for not looking at it.

And if he had, and if the tailwinds had been light, perhaps he still would have elected to land upslope with a tailwind. But if he had been cognizant of a tailwind, I wonder if he would have been quicker to pull the trigger on a go-around when things went awry.

The pilot stated to authorities, “I waited way, way, way too long to go around,” but in the end, “I did not feel like I had enough room to abort the landing, so I chose to lock it up.”

Slopes and Tailwinds

Let us do what the pilot would, no doubt, like to do: Go back in time before the crash. If he had checked the wind, would it have changed his plan?

The slope of Runway 35 at 7A8 is a pretty respectable 3%, meaning the far end of the runway is 33 feet higher than the close end.

Using the standard rule of thumb, on landing, this uphill slope would have had the effect of making the 3,001-foot runway seem to the airplane as if it were nearly a third longer at 3,900 feet, what is sometimes called “performance length” (every 1% of gradient is equal to a 10% increase or decrease in effective runway length).

Of course, the opposite is true, with a reduced performance length, had he chosen to land downhill. Now the 3,001-foot runway “becomes” 2,100 feet.

Of course, that’s all without wind. So the real question is, when weighing tailwind vs. slope, how strong does the tailwind need to be to overcome the landing advantage of a slope?

The answer to that, in this case, is roughly 6 knots, which would increase landing distance by 30%, as landing distance — again as a rule of thumb — is increased by about 10% for every 2 knots of tailwind.

Another way of saying all of this is that you can make a case for landing uphill here with a tailwind of up to and maybe a little beyond 6 knots, as the slope and the wind cancel each other out. With tailwinds stronger than that, the wind will start “shortening” the length of the runway (performance-wise). But at this point, if you turn around and land into the wind, the headwind is now off-setting the downhill slope.

The Takeaway

So what’s our takeaway here? I see three.

1. First, don’t underestimate tailwinds. It doesn’t take much wind at your back to have a big impact. No pun intended.
2. Second, be alert to plan bias and remember that, in aviation, very little goes according to plan. But that’s what makes it fun.
3. Third, always be primed to go-around. Regardless of all the other factors, if the pilot had deployed a go-around early in the float, we wouldn’t be talking about him from where the wind was — behind his back.

The Numbers

Want to read more? Read General Aviation News’ Accident Report here. Download the NTSB’s final report here or view the items on docket here.