Winds of Change.....

Since we've had fairly low and windy weather much of the week, I hadn't had a chance to fly since Sunday, and with a little free time this afternoon, I figured a gas run would be a good idea. There was a line of weather to the north, roughly paralleling the Texas coast, but all of the motion was along the line, and the line itself was sagging only very slowly south towards us. My usual cheap fuel airport is about 20 minutes up the coast, and I watched the XM for a few minutes to see if the timing was going to work - it would be close, but I had several good options of other place to go if I guessed wrong and lost th race, so there was little danger of a problem.

When I took off from home base, the wind was 160 @ 9, gusting to 21, so I trolled out and took of on runway 14. I made a very quick trip over to the fuel stop, turned around in just 7 minutes (taking on 25 gallons of fuel at $3.47/gallon - darn cheap these days!), and was headed back to home base. the line of weather was creeping slowly south, and as I approached th field, I actually passed under what looked like the roll cloud, but it was 1500' up, and the visibility was excellent - the rain hadn't really started. Not wanting to waste any time (since I had ridden the motorcycle to the airport, and didn't want to get wet!), I entered directly onto the downwind for 14 as I came in from the east, and took quick look at the wind sock - straight down the runway. Our AWOS transmitter has been a bit intermittent, and I wasn't hearing anything, but no matter - there was no traffic, as the weather looked worse tan it was. As I turned base to final, I was surprised to overshoot quite a bit - but then, I was still carrying carrying excess speed, decelerating nicely for a touchdown. I glanced again toward the sock - still straight down the runway.

As I crossed the threshold, I thought "wow, I'm going fast!", but the touchdown was smooth, and the roll-out easy to control - and as I passed the sock at mid-field, it was straight down the runway - pointing the WRONG WAY! I punched the AWOS button again, and it had come back, now calling "...wind 330 at 10, gusting to 22..." !!

Holy smokes, a 150 degree change in wind direction, and an absolute gust value change of more than 40 knots in just 40 minutes - quite a surprise! of course, when I glanced at the wind sock, I "saw" just what I expected to see - it was parallel to the strip - and my brain didn't look for witch end was pointed which way.

No harm, no foul in this case, but an interesting thing to remember - the winds really Can change that fast, and with no other traffic on the CTAF or in the air, it is easy to just land the same way you took off....

(Oh yeah, the temperature dropped about 30 degrees as well - the front had more power than it appeared!)

Paul

A wind change like that doesn't supprise me. Just the other day I was coming in to land at my airport and there was a chopper doing touches on the left and I was coming in on the right. winds were being reported as 260 @3 gust to 18. No big deal I'll just do a touch first and come back around for a final. I did the touch and the sock was around 260 straight out, did a wheel landing and went around for the final. I was on my short base when the chopper was told that the winds were 260@18. Ok I'll do a left side in on the runway and nose it slightly into the wind and do a three point, fine and dandy except as I was on the final and took a quick look at the sock (at the start of the runway) it all of the sudden rotated to about 160 straight out(time it took do this was about 2 seconds), oh cool I thought, I flattened the decent and flat turned it to the 160 heading and also let it drift to the right side of the runway, then let it settle in perfect 3 point on the runway. I think if I would have just done the normal wing low into the wind with rudder to center down the runway and the wind did this, I may have had the left wing come right up on me. By the time I got off the runway and taxi'd back the winds were back to 260. Oh! the runway runs 210.

One night I took off in my 9A to do T&G's to stay current. I took off on 17 after looking at the sock. I literaly stayed in the pattern, came around set up for landing and used 2,000' of runway to land & roll out. Thinking I was just rusty I tried it again, again, same result. I then happened to look at the sock and the wind had shifted to 35 @ 12 knots! This took all of 10 mins!

Then I remembered my instructor telling me to take one last look at the sock on final. Good rule to fly by.

A state park here in Indiana used to have a grass strip and we would often picnic there. On one flight I overflew the strip and saw that they had installed a wind tee. Cool! It was straight down the runway. DW, base, final, flare--this 172 sure seems to be really moving. As I touched down I went by the wind tee; it was a backhoe laid out on the ground--pointing the wrong way. We've all been there...

Bob Kelly

I always look at the windsock as I turn final. Monday the tower called the wind calm and as I came down final I could see I had a 6-10kt direct tailwind. Landed anyway for the practice but was ready for it. The wind at this airport can change 180 degrees in minutes. I have seen 4 more than 90 degree wind changes in a half hour touch and go session. Good for keeping on your toes. Don

And the verdict is - ?

Paul: So, in retrospect, faced with the same information, would you now make the same decision? Or is this a "lesson learned" story?

Here's one from my past:

I had a very close scrape (literally) with a rapid wind shift on takeoff, no less, but I didn't notice the virga overhead that would produce windshear for our takeoff that day:

I patiently waited for winds to shift around to the west for a departure out of Longmont CO at the Rocky Mountain regional flyin. Conditions for windshear that day were moderate: virga nearby, low cu's in the area, and gusty winds. My student was flying left seat in the PA28-180 and I noticed a small spattering of rain on the windscreen just before we broke ground. The Cherokee climbed out well considering the three of us on board (his wife too) with full tanks, and some gear in back. But all that went away at approx 200-300 AGL when airspeed dropped off and our climb deteriorated into a steady sink. I took the plane shortly after the windshear hit. We got to about 50 feet over a grass field, and as I surveyed the terrain/obstacle situation I noted the grass blown flat to the ground right on our tail I had a few seconds to make the decision to continue to fly or put the plane down while I still had flying airspeed. The "out" in this case was that the terrain gently sloped downhill to the northwest, and it was fairly obstacle free. So I eased into a gentle right bank, maybe 10 degrees, and just hoped for enough time to fly out of it. And that we did - after spending what seemed like an eternity waaaay to close to the ground. Thank God all the windshear training I'd received payed off that day.

Lesson learned: When surveying your takeoff or landing weather, check overhead too! Not even the most advanced onboard windshear system would have detected that one.

Paul, thanks for sharing. Reminds me of the time I was going into Helena, MT a couple years ago. The vis was about 3 miles in smoke. I called tower around 10 miles east after listening to the atis. Now, I don't know how unique this is, but there are three wind measuring systems at the Helena airport. The tower advised me that all three winds were at 90 degrees to each other, all in the 15g20 range. I was beginning to think this wasn't a good idea. I was straight in for 27 or about that, and the wind at the east or approach end were out of the east. However, the winds at the west or departure end were westerly. I guess that explains why the winds were from the south on the north side of the airport, since those easterly and westerly winds had to go somewhere. You all with me still? Anyway, they cleared me for 27, and I told them I'd plan a touchdown towards the west end (I think it is around 2 miles long). On final, gps was showing that I had about a 20 knot tailwind. I flew along the runway at around 15 feet until I was maybe 3/4's down the runway, then landed. GPS showed something like 50 knots ground speed when I decided to land. There were some interesting control inputs during that little runway flight.

Bill Wightman said:

Paul: So, in retrospect, faced with the same information, would you now make the same decision? Or is this a "lesson learned" story?
.

Click to expand...

Several lessons, but the most important is never assume anything. I fly in and out of that field like it's my driveway - I can do it almost in my sleep. No traffic, no one on the radio - land on the runway you took off on a few minutes before! And, of course, just took a Quick look at the sock. So the lesson is - stay sharp!

The landing was actually no problem, and by the time I realized my mistake, I was already pretty slow. If I had seen the sock on final, I probably would have gone around - I don't usually tempt fate in a tail dragger! Once I id see what was going on, I instantly went into "hi gain" on the rudder - I wasn't going to let any sideways motion develop at all, and it didn't.

Never assume, and if you see what you expect to see, take another look!

Paul