Wicked Winds

Aviation General Aviation
1

Heading home to Spearfish, SD after golfing earlier in the day in SE Colorado (La Hunta) the winds were building and as I flew over the last half of the Black Hills, I noticed my plane was flying cocked a bit as I continued a northern heading. Groundspeed was dropping as the very strong side wind continued to increase. It wasnt anything unexpected, I checked the weather while in La Hunta and I knew there were winds above normal forecast and my 496 weather satellite feed kept me informed of wind speed and direction. I also knew winds in Rapid City were reasonable from watching the 496 during my flight so an out was always nearby.

20 miles south of the Spearfish airport I listened to ATIS report direct crosswind guts of 70mph. I called Unicom to confirm; sure enough the airport manager confirmed wicked winds, no error in the ATIS report.

I began my descent from 10,500 and at the time the turbulence wasn’t too bad. I’d flown the last hour with the autopilot off because it was rough enough I didn’t want to over work the servos. Descending into Spearfish is often rough since the airport is surrounded by the Black Hills. I should have just diverted to Sturgis or Rapid City before descending but I wanted to get down and see what things looked like.

When I dropped to 1,500 agl a few miles SE of the airport the turbulence was very significant. It was obvious I wasn’t going to land in Spearfish. I called the Unicom in Sturgis and they reported light winds, hard to believe since its downwind from Spearfish and only 18 miles east. As I turned to make Sturgis my new destination the turbulence was too much to handle.

Winds at the time of my descent into Spearfish around 4:30PM Sunday 1-27-08 had been clocked at 101 mph and a semi truck had been blown off the hi-way a mile from the airport. This information gained after the fact helped explain why I was being thrown all over the place.

I could no longer go with the wind toward Sturgis, it was too dangerous. I turned back against the wind and climbed to 8,000 trying to rise above the worst of the turbulence. I headed northwest during the climb toward the Belle Fourche airport, which is 12 miles north of Spearfish. Although the winds in Belle were very high, which was apparent from all the dirt blowing, I descended anyway to 4500 to look at the windsock and get a feel for the turbulence closer to the ground. Belle Fourche is 3200 feet and has no ATIS and no one answered their Unicom frequency. Winds were straight out of the west and blowing as bad as Spearfish. Turbulence was rough as well.

I climbed back to 8000 mostly into the wind since I felt I had more control heading into the wind. The lower speed against the wind made the turbulence more tolerable. I knew I needed to get away from the Black Hills because when I turned with the wind again Id be like a kite and I wanted to be over the prairie. When I reached 8,000 I reduced power to 2000 rpm and 18 manifold pressure and turned with the wind, within 20 seconds I had a ground speed of 220 mph.

I continued to talk to the Sturgis Unicom; they were reporting winds of only 10 mph, straight from the east. I said are you sure, Im being blown east like a kite. He confirmed winds straight down the runway from the east and he told me to land on 11 if and when I could get there. I told him I’d continue northeast with the wind till I could come into Sturgis from the northeast. While I was being blown to the east it was rough but tolerable, I was flying with almost no power over 200 mph as I continued east of Belle Fourche 30 miles.

When I got north of Sturgis I tried to begin a southerly heading to the Sturgis airport. I turned south but the winds continued to blow me east and I couldn’t get much headway toward the south. Although I was feeling a little nauseous, I was feeling better now because I knew once I got down and near the Sturgis airport, landing would be no problem. I wanted to head to the airport against the wind since I felt more in control going against the wind. I was looking forward to being on the ground, this had gone on to long.

After reaching a point about 35 miles northeast of Sturgis at 5,000 agl I started a sharp descent while heading southwest and finally made up some ground and as I got to 1,000 agl, I was finally within five miles to the northeast of the Sturgis airport.

When I landed on 11 the wind was in my face and the sock was straight out blowing 20 mph. I was very happy to be on the ground. Everything in the plane was thrown around and I hit the ceiling once so hard my headset flew off in spite of my belt being tight.

It was good to be in contact with the local Sturgis Unicom since he gave me hope if I could get to him, I’d be able to get landed. Trying to avoid getting to nauseated was a big problem since Id been in this turbulent mess for about 40 minutes.

I’ve landed at 150 different airports and the Black Hills continue to be the worst weather I’ve faced. The Rockies and the Big Horns and the Wyoming prairie can generate some real wind speeds and turbulence. If you fly in this country you kind of know what to expect and every once in a while it hands it to you in spades, today was one of those days. Seven years ago a straight-line wind destroyed all the hangars at the Spearfish airport. I often face rough turbulence descending into Spearfish, this was the roughest, at least we have all nice new hangars.

2

Wow, crazy windy. Nice job getting it down safely.

Oh, and moon? It wouldn’t hurt to post a little more often… :wink:

3

I’ll do that, I sure enjoy lurking. Thank you for the reminder. :slight_smile:

4

I’d say you pretty much made up for it today! Which Mooney do you have? The worst turbulence I’ve felt in a GA plane was in an Ovation.

5

I love reading about flying challenges such as yours. I force myself to practice in gusty winds but your story puts any winds I have been in to shame! Glad you survived it to share with us.

6

Having only crossing the Appalacians mountains experience, my mountain flying skills are practically nil, so take the following with that caveat.

My question would be, what was the forecast before your wheels went up.

If I remember correctly, in that portion of the country, the forecast was for widespread high winds.

There has been some potent weather systems this past week causing widespread airmet “tango”, but that may be perpetual in that area based on terrain just like airmet zulu is for the NE part of the country in the winter time?

In my experiences down here, the winds are usually within 20 to 30 percent of the forecasted values (I.E. forecasted winds may be 15 knots, but we end up with 20)

My next question would be, did the preflight weather forecast fail you or did you test your limits?

I do know those conditions would have skeeeered the “KRAP” (closest NWS reporting station) out of me :smiley:

28 17:52 N 47 G 59 10.00 Fair and Windy CLR 5 -4 29.39 998.2
28 16:52 N 54 G 67 10.00 Mostly Cloudy and Windy 29.31 995.4
28 15:52 N 40 G 57 10.00 A Few Clouds and Windy 29.24 992.7
28 14:52 N 41 G 52 10.00 Fair and Windy CLR 19 9 29.14 988.6

Above taken from
weather.gov/data/obhistory/KRAP.html

Incredible altimeter change in the above time frame!

Allen

7

29.14, holy crap that’s low. Winds at 41 G 52, I would have sat that one out.

8

Great story moon. FYI, the winds aloft on satellite weather fed to your 496 are forecast winds rather than actual (with one minor exception). The last time I saw this analyzed, the winds aloft forecasts were shown to be the least accurate of all aviation weather forecasts. The satellite weather wind for ground stations is the most recent ATIS/AWOS report for each station, so those are actual.

9

lieberma

My question would be, what was the forecast before your wheels went up.

I looked at the weather before leaving La Hunta, CO, I knew it was windy enroute and likely to windy to land at Spearfish. The 496 showed winds at 10,500 from 30 to 50 mph for most of the trip. In five years based at Spearfish there was only one other occasion I landed at an alternative airport because of wind. Usually if a flight is cancelled altogether its because of a snow storm or rain storm requiring IFR or no go because of ice.

If I remember correctly, in that portion of the country, the forecast was for widespread high winds. .

We have higher winds on average than many places. Wyoming has the highest average wind speed in the Nation. Spearfish is 10 miles from the Wyoming border. Between the Rockies, the Big Horns the Wyoming prairie and the Black Hills of South Dakota, wind is a normal forecast. It is unusual if I have a smooth flight between Spearfish and Denver, which I do a couple times a month to see my son and his family and/or ski or hike the Rockies where I have a condo in Dillon.

There has been some potent weather systems this past week causing widespread airmet “tango”, but that may be perpetual in that area based on terrain just like airmet zulu is for the NE part of the country in the winter time? .

On top of the contributing factor causing high winds, Spearfish sits in a bowl surrounded by the Black Hills. Its very beautiful but generally turbulence can be expected. Ill often descend from 10,500 to pattern altitude and have to reduce my speed and rate of descent because of turbulence.

My next question would be, did the preflight weather forecast fail you or did you test your limits?

The preflight forecast winds I encountered enroute were accurate. Of course there was no forecast of winds speeds on the ground near the airport of 101 mph. The flight was estimated at three hours, I didnt call ATIS for Spearfish winds, but my 496 showed my alternative in Rapid City with winds at 10 mph during my entire flight north so I was never concerned about being able to land near home.
Guy

10

FYI, the winds aloft on satellite weather fed to your 496 are forecast winds rather than actual

I know they aren’t overly accurate, especially when I’ve got a strong headwind and I’m supposed to be flying with the wind according to the 496. They’re pretty good in general though.

11

Which Mooney do you have? .

I’ve got a J model

12

29.14, holy crap that’s low. Winds at 41 G 52, I would have sat that one out.

Lawrence County Journal 1-29-08
The latest cold front to move into western South Dakota brought some wacky weather with it, including temperature drops of 50 degrees and more than 100 mph wind.
The National Weather Service in Rapid City reported the temperature dropped from 55 degrees at 1 p.m. to 4 degrees just before 5 p.m.

Other areas around the Black Hills reported similar drops.

Winds of up to 70 mph were reported near Hermosa on Monday afternoon, but the most severe winds were recorded Sunday near Spearfish.

Those winds battered the Spearfish area over the weekend, capped by the crescendo of a 101-mph blast Sunday afternoon.

National Weather Service meteorologist Eric Helgeson said a weather spotter measured the 101-mph gust 5 miles west of Spearfish at 4:50 p.m. Sunday afternoon.

Earlier in the day, a site in Deadwood notched a 60-mph reading at 3:45 p.m. At 2:05 a.m. Sunday morning, a 78-mph wind reading was recorded.

Helgeson said winds were clocked at lower speeds on the plains around Spearfish because of a little-known phenomenon called mountain wave gravity. He said the event is more common in the Rocky Mountain area. What happens is, southwest winds blow up the hills from Wyoming and come down on the east slopes, crashing down like a wave.

A semi truck driver caught the wave around 1 p.m. Sunday when his truck and semi trailer he was driving west on Interstate 90 near Spearfish, tipped over on the interstate. The truck and trailer came to a rest on its passenger side, across both westbound lanes. The driver and his passenger, suffered minor injuries.

The Spearfish welcome sign near the Spearfish Post Office was smashed.

13

Which probably reaffirms leardvr statement which I was trying to subliminally hint.

The pressure gradient indicated by the altimeter changes just in the hourly observation would clearly indicate a high wind event, even down here in the flatlands of Mississippi. I can’t imagine what the mountain terrain would do to the wind fields of that magnitude…

Preflight briefing would have brought this out, as well as upstream wind observations.

I can see how quickly weather forms in your part of the country and I can see how 24 hours before that some of the severity was potentially not forecasted.

hpc.ncep.noaa.gov/dailywxmap … 80127.html
hpc.ncep.noaa.gov/dailywxmap … 80128.html

I am surprised you didn’t indicate that you saw any surreal cloud formations or lenticular clouds in your flight resulting from that gravity wave???

It sure is better to be wishing to be up there then down here…

This is not anything against your piloting skills, you did what you did to bring it down to terra firma to share with us, but it appears to me from this pilots point of view you did put yourself in a position that could have been avoided from get go especially if you got a preflight briefing BEFORE your wheels went up on Sunday…

Of course, I do recognize your wind limits just by virtual of where you live would be much higher then mine. 30 knot winds this way is not CAVU, it’s a hunker down severe weather event day where your way, it may be a Xwind warm up lap around the pattern type of day.

Everytime we leave terra firma, it’s a learning experience and there is no text book answer, just common sense here.

Allen

14

but it appears to me from this pilots point of view you did put yourself in a position that could have been avoided from get go

Allen,
When I left Spearfish on Saturday at 9:30 AM we had a high pressure system over the area. Pretty much from north of us through Texas. That same indicated high pressure system was in affect through Sunday. I love it when there is a big H over the areas I’m going to be flying.

I’ve seen rotors and lenticuler wave clouds many times along the front range of the Rockies. The clouds weren’t showing any of the classic rotors or wave patterns while I was approaching from the south. I’ve taken two mountain flying courses, the most recent this past summer put on by Sparky Emmerson.

I fly a lot in the Rockies, when winds are above 30 mph I’ll fly 3 or 4 thousand feet above the terrain, so I often have oxygen on over the Rockies. I certainly respect the heck out of winds and generally get my flying done before 1:00 PM in the summer. Wintertime flying in our country is the best, colder the better means more stable weather unless there is a storm situation. I avoid thunderstorms like the plague.

If you let 30 to 40 mph winds aloft keep you on the ground you’ll spend a lot of time on the ground up here. If wind speeds on the ground are much over 20 I’ll avoid leaving the airport, if they’re 25 or less down the runway I’ll depart.

I’ve landed many times with winds in the high 20s as long as it’s pretty much down the runway. Over those speeds and I’ll be looking for a new landing place.

I always knew Rapid City had winds in the single digits and clear and this was being monitored on my 496 from their awos feed. I knew Sturgis had single digit winds as well. I would have saved myself a lot of rocking and rolling if I’d just diverted to Rapid City immediately while I was at 10,500 and 20 miles south of Spearfish after hearing ATIS. Dropping down to look things over was pretty much unnecessary.
Guy

15

Let me stress again, my mountain flying experience is next to nil, so using that caveat accordingly certainly take this into considerating, as really other then the “numbers” that seem way more intimidating, I can only think outloud on what your decision making process was, it’s not for me to say right or wrong as I recognize geographical weather changes the definition and higher go no go decision.

In simple words, I can’t judgemental on your experiences (or even decisions) as I don’t have any to relate too, much less any training, this is more like keep asking questions for learning for myself. I just have never seen a wind forecast bust by that wide of margin, thus my questioning. Hope this makes sense.

In the winter, what you say is very true especially when the lower jet moves down here. Not unusual here to be calm on the surface and have 50 knot winds at 2000 feet. Bumpy as all get out through that transition, but no mechanical induced turbulence like you encounter. And of course, down here, picking through fields of T’storms is an art by itself during the summer days.

My personal current cutoff is 30 knots, and 20 knot Xwind component. Like I said earlier, GENERALLY, if the winds are that high down here (my field elevation is a measily 325 MSL) then I have probably bigger issues happening then preflighting my plane. And I recognize, like you said, just the weather is soooo much different up your way and parameters for go / no go will be much higher, mainly because you don’t have a choice.

I have to admit, you fly at nosebleed altitudes as compared to my way. 10,5K is just about 2 miles AGL! Plenty of air to glide through should the fan stop. :smiley: Seriously though, I wouldn’t want to be using my Sundowner to slog around the Rockies! Highest I ever been thus far, and that was just playing was to 10K during an cool evening! And at that altitude, I could see the Mississippi River from where I fly near Central MS!

Allen

16

I have to admit, you fly at nosebleed altitudes as compared to my way. 10,5K is just about 2 miles AGL! Plenty of air to glide through should the fan stop.

Allen,
Living this close to the rockies does have a lot of advantages. I’ve flown to Jackson Hole, skied the day and flown home the same day. This is what the morning looked like as I started down the runway.http://www.cessna.org/forums/attachments/457738-SPF12-06.JPG

17

Cool, and agree, planes make the world a smaller place.

Password protected??? get prompted for username and password when clicking link for picture.

Allen

18

Password protected??? get prompted for username and password when clicking link for picture.

Allen,
Sorry about that, I guess until they update the image system so it can come from my computer I won’t be able to attach a photo.
Guy

19

JMHO: Sounds like Allen thinks Moon made a few bad choices. Stop tap dancing and man up. Tell him how you really feel. Make believe he is Damiross. JMHO :imp:

Disclaimer:JMHO

:stuck_out_tongue:

20

I find that the wind forecasts are much less accurate in the mountains than elsewhere. In addition, there are major local venturi effects (remember Bernouli?) as the wind compresses and speeds up through mountain passes. So you can have localized wind speeds and directions that are very different from what the winds aloft forecast would suggest in the mountains, and the actual winds aloft can be very different from the forecast. Jackson Hole is one of the classic examples as the winds from the high plains come up against the jagged Tetons with the airport immediately on the other side. Lake Tahoe is another one with 11-12,000 foot peaks coming up from sea level over a short distance and the Truckee airport on the other side of the lowest (8,000’) pass. There are times when the two wind socks at each end of a runway are sticking straight out in opposite directions.