Mountain Winds

[Daz]

This is an *awesome* thread!!

 

I'm a 100-hour wonder who has lived and worked in the mountains for the past 18 years. I hope to someday fly in the mountains (for now, I'd be very happy pushing a broom in a hangar just to be near helicopters, but that's another thread...)

 

During my training, I got to spend a few hours in the mountains with a very experienced instructor (thanks, Richard!), and it gave me an entirely new respect for mountain flying. I got a brief introduction to boundary layers, delarcation lines, contour crawls... enough to really get me addicted.For a newbie, it was exhilarating, freaky, and informative all at the same time. Since then, every time the wind blows, I try and picture it flowing around the mountains like water flowing down a rocky stream. There *will* be a mountain course in my future - even if I have to sell a kidney to afford it.

 

Keep the posts coming!!

 

... Darren

[skullcap]

Flying or ferrying in wind can be very disconcerting if you do not understand the relationship between wind and terrain. The most horrific turbulence I have experienced while flying has been no where near mountains but in rolling country with 40kt winds. The force of one strong bit of turbulence caused my head to hit the door post of 206 so hard am sure would have knocked me out had I not had a helmet. Having said that the strongest upflowing/downflowing winds I have encoutered were in the eastern slopes of rockies. More than once had 2000 fpm rate of descent while pulling 100% torque at best rate of climb speeds.

 

So when planning a flight with winds take into account the type of terrain and the load on your aircraft. There are people who will say the ride is smoother with a heavier machine but think is safer to keep the aircraft light if able, especially in big country where the wind has more strength. Remember that a 5 kt wind in the valley will accellerate up/down a mountain to become much stronger with the height of mountain side.

 

Stay to one of valley when able,,,you will be taught to stay to right to avoid traffic but the right may be in too much downflow. But even if in the downflow side the wind should be more consistant than the middle. (plus that is usually where the fixed wing are).

 

Make lots of radio calls if on a vfr corridor.

 

When leaving the mountains for foothills in high winds you may feel that it is better to stay high, thinking the turbulence is less. But even where there is no mountain wave there will be strong turbulence which you cannot estimate when or where it will hit. So I always stay low and closer to terrain, this enables you to tell the strength of wind and can slow down to safer speeds to avoid the heavier turbulence.

 

So, in rolling hills in strong winds I tend to stay high to avoid the worst turbulence. In the mountians and lee side of moutains I stay low. Bout it.

 

 

 

[TopFuel]

Gold Member touched on the 5 knot updraft equalling 500 fpm. The exact opposite is also true on the down draft side (which can be a little scarrier!).

 

There will always be pads you need to go to on a slight (5 knots) downdraft. Your are marginally heavy but well with in a comfort level. Your approach may be all on the money 100' fpm...nice and slow (but not to slow) and you try to stop the decent prior to the pad, and realise that you have to arrest a 600 fpm decent!!

 

I was shown early on...how to "climb" into a pad on the downdraft side. One of the best lesson I have learned so far. Thanks Raynor!

 

[Black Mike]

Wow a great thread so far, but I was thinking about something I said earlier on, and it raised another set of questions. It was about this time of year being great for meeting people as fire ships passed through to get to their various contracts.

 

My question is this, on cross country trips (well away from your normal operating area) when does wind and turbulence shut you down. I guess this is also in part to me hearing that Robinson will not let a low time pilot ferry new helicopters from Torrance (think that is a D.A. issue not wind and turbulence).

 

I am thinking more of mountainous terrain again, east of L.A. in Robinsons case, but also the Rockies and the Mountain ranges in Canada.

 

As I know this is a bit of a broad question I will try to narrow it down a bit. In the case of the mountains around Whistler B.C. (been there a couple of times to ski, so am vaguely aware of height and shape, plus it is in Canada so most on this forum may know the area), how does wind and turbulence affect flying?

 

Lets say winter, low pressure approaching so wind out of the south/south west, wind in the valleys 10-15 knots, ridge tops 15 gusting 25.

 

What is the best transit altitude, way high, 1000 to 1500 feet above ridges? Down in the Valleys at 500 Agl and mountain passes? Punch through perpendicular to the ridge or at an angle?

 

How far downwind from a ridge does the worst turbulence extend? If you get in to bad turbulence what do you do? Turn around, Climb above it, Descend?

 

Do Lenticular clouds help you decide not to go anywhere or is that indicative of laminar winds?

 

Would wind shear be unsafe? For a 206L, Astar, R44, 212?

 

What if winds are higher 25 gusting 45 on the ridges?

 

What about lower winds, 10-15 on the Ridges?

 

Best penetration air speed for 206L, 407, astar, R44, Hu369? Is being heavy (full fuel) better that being lighter?

 

In this scenario I am not talking about landing, just transiting the mountains to get to the other side.

 

I know that this is a lot of questions, but I am interested to know more for if I ever get a call to ferry a ship cross country, and it seems like a ton of really knowledgeable pilots are on this forum.

 

Thanks

 

Mixmaster

Mixman,

 

Sunday night, not much going on, I will pass on a few tips that I have learned,

 

Lenticulars: normally means things will get rough. I, however have seen them form on the highest peaks with about 10 knot winds, no big deal. (this was on a 13,000+ peak near our home) Generally however they are not a good sign for things to come.

 

45 knot gusts on a ridge- go home- this is pretty straight forward for here- leeward side of coast (Cascade) mountains- central B.C. you don't want to be here.

 

I tend to keep to the upwind side of the valley- no traffic here to worry about but generally if you get blown around, at least it should be upwards according to the books.

10-15 on the ridges can be your friend- approach higher (not too high) come in about 45 deg. to ridge, I prefer approach left to right- you can see better, escape route is out your side window (LongRanger) Terrain and wind speed/turbulence will judge what angle you need. The steep approach idea that some people use, or talk about doesn't work here if you have any kind of a load (you always do, as why would you go there by yourself) If using the high angle approach, make sure you have a case of tail booms at home, you'll need them.

 

There is no worse feeling than 20 feet above the ridge pad, 30 percent torque, heavy load, not moving anywhere, up or down.

 

500 feet is plenty above ridges on crossing- I have tried lots of different elevations above ridge level and it is just luck of the draw. Get a helmet as you will wack your head on the door post.

 

One thing that you need to do, no matter what or how you get there, at a few hundred yards out from your ridge landing pad, you need to be slow, disc loaded as best you can, 100 feet above or so, and aim for your spot. If not good feeling,- ie you are directly above the pad by 20-50 feet or so, go around OR use the sideways approach to a different pad- this only works if you can keep moving forward a little- pad to 1 or 2 o'clock position, gradually creep down as you move over, keep the escape route in front!!! You are too far forward to do a 180 at this point. Watch out for rocks and trees as this was not the intended landing site. If in the snow, remember that you need a reference there as well, watch for the snowdrifts under the tailrotor.

 

Hope this helps, time for (Canadian) beer again.

 

B.M.

 

 

 

[Hello-bird]

This thread is a dream. Wind (ie: the atmosphere in motion) is the subject of my paintings. This thread is the best thing I've read in a long while. Like a gust of fresh air.

 

A close friend (and fixed wing pilot) gave me a book on Wind. It's not any kind of training manual, but it's on everything about wind. Fantastic read. I'll include a list of a couple others I've found in researching the subject (incase they may be of interest.).

 

 

Wind: How the flow of Air Has Shaped Life, Myth and the Land ~ by Jan DeBlieu

 

Living With Weather (Along the British Columbia Coast) ~ by Owen S. Lange

 

The Wind Came All Ways (a quest to understand the winds waves and weather in the Georgia Basin) ~ by Owen S. Lange (Environment Canada).

 

 

Looking forward to reading more here...

 

 

 

 

 

[Jet B]

This reminds me of the first lesson taught by the crusty old guy who did my mountain course years ago...

 

"First lesson boys is that your a$$hole is the boss, when it starts grabbing that seat stop what you are doing and get out of there!"

 

That rolled into the second lesson which was to keep an escape for as long as possible and avoid commiting until the last possible moment so you can change your mind when the boss starts clenching and grabbing that seat.

 

Then you start doing long line jobs on the downwind side of the hills and all your mountain techniques get thrown out the window... I am no expert and still have a lot to learn. I have found that when you do have to operate on the ugly side of the mountain, it pays dividends to really be able to listen to what your machine is telling you. Nothing is as good as knowing exactly what the wind is doing to your machine. It's actually those days with the light and variable wind that have scared me the most. At least when it's blowing 30 knots, there is never any doubt where it's coming from.

 

 

 

[Skidmark]

Mr. Mix

One "rule of thumb" for doing cross countries through mountains that was passed down to me a few years ago was to stick to the sunny side of the valley. Usually makes for a smoother ride on those not so blowy days.

 

If you want to jump on a steep learning curve cross the border at Montana and make your way to a place called The Crowsnest Pass. I'm sure they have to regularly grease the bearing in the windsock at The Gap Forestry Base.

 

This wind art thing sounds interesting too. Do we get a preview?

 

 

[Zazu]

QUOTE (Jet B @ Mar 23 2009, 02:03 PM) <{POST_SNAPBACK}>

This reminds me of the first lesson taught by the crusty old guy who did my mountain course years ago...

 

"First lesson boys is that your a$$hole is the boss, when it starts grabbing that seat stop what you are doing and get out of there!"

 

That rolled into the second lesson which was to keep an escape for as long as possible and avoid commiting until the last possible moment so you can change your mind when the boss starts clenching and grabbing that seat.

 

Then you start doing long line jobs on the downwind side of the hills and all your mountain techniques get thrown out the window... I am no expert and still have a lot to learn. I have found that when you do have to operate on the ugly side of the mountain, it pays dividends to really be able to listen to what your machine is telling you. Nothing is as good as knowing exactly what the wind is doing to your machine. It's actually those days with the light and variable wind that have scared me the most. At least when it's blowing 30 knots, there is never any doubt where it's coming from.

 

HA!! Couldn't agree more. My instructor (really old and really respected) told me much the same thing...add French Accent and go from there "go by zee book if you can but these not work all zee time...you no like...well...you geet zee f##k out!!!...or, you know...you clrash...you die!"

 

Boy was he right! "Know your ***", "know your limits" are right there at the top of the list for flying in the Mountains...at any point of your approach if you don't think you know..don't go!