Mountain Flying

[remote hook]

Paco, Arm out the Window,

I'm not sure where your moutain experience is, but flying like you describe is a sure way to end up in a ball of twisted aluminum. As Rotorboy a Crab say, a shallow approach to a specific spot, AFTER very acurately determining the horizontal and vertical components of the wind is the way to go.

Your theory of the steep approch and your so-called "way out" is hogwash at high altitudes and in loaded machines, particularly N1 limited ones like the Astar. The shallow approach in known wind allows for an overshoot to be made up until the last few feet in most cases, while affording a detailed view of the chosen landing area and providing the pilot with ample "feedback" from the machine to make the landing decision.

This is a method that works EVERY TIME, not 98%. Playing with the demarcation line on a steep approach is nice in light wind, but in heavy wind, steep terrain, and in a loaded machine, you're asking for it. These are not oil rig approaches in twins....

RH

[Arm out the window]

rh, what do you mean, the 'way out' idea is hogwash?
If I'm approaching along a ridge line and there is descending terrain each side, there's good 'ways out' all the way in.
To answer your question about experience, I've done some mountain flying in crap conditions, but not a lot - probably nowhere near as much as you guys do in Canada.
Shallow sounds good if you're in the updraft air, but a horse's arse if you're on the lee side of the ridge - I guess your response there would be that you wouldn't approach from that side.

[SAR Bloke]

I like the shallow approach too.

Arm out the window, why is a shallow approach 'a horses arse' idea on the lee side of a mountain? What makes the steep approach better in this situation?

[Gas Producer]

SAR Bloke,

The turbulence might have something to do with it.

[SAR Bloke]

So how would a steep approach help in turbulence?

What if the cloudbase was 50' above the landing site?

[Arm out the window]

If a strong wind blows over a ridge line or hill top, obviously the flow will be complex and hard to pin down in some cases, but according to the met people there's a so-called 'demarcation line' above which the air is smooth-ish and rising (starting at the top of the hill and sloping back with height in the direction the wind's blowing), and below which it's turbulent, unpredictable and generally downdrafting.
So, all other things being equal, if you approached in the more favourable area (above the 'line') it should keep you in cleaner and upward-moving air.
Obviously the real world isn't so easy to pigeon-hole, but as a guideline it makes at least a bit of sense to me, hence the idea of a steepish, SLOW approach.
If there's cloud 50' above, then of course the plan must change.

[CYHeli]

Slow can be good.

Another reason for flying slow (not hover taxi) is that if you get caught in turbulance, if aren't going to hit VNE. Remember VNE changes in turbulance, I'm not talking 120 - 156Kts normal VNE, I'm talking whatever the turbulance limit is for that machine. That will change with DA, AUW...

If you come in too quick, the winds is a bitch and you decide to point the nose down the hill and get out, you don't want to be going too quick.

Another thing is that you need time to assess what is happening.

[jemax]

I was asking my mountain flying instructor about wind and he told me he never had a problem with it,

"If it's more than 10 kts we dont fly, no problem"

Sensible advice especially for the inexperienced, for info he was the best pilot I have ever flown with at for doing zero/zero's as it's all he ever did up there.

[paco]

I've been using steepish approaches for the past several years in Alberta and BC and I'm still alive. I've always questioned the shallow approach, and I'm not saying I won't ever use one (cloudbase is one good reason as SAR Bloke suggests), but I will always try steep first. And you certainly shouldn't go shallow with powdered snow...

And if it's too high and too windy, you shouldn't be there. Period. Time to get a better machine.

That said,

[remote hook]

Powdered Snow??

The shallow approch to a slight run-on landing in ski ops IS THE WAY. To come to a high hover, or slow decent with no forward speed for that matter, on an overcast day with fresh snow is really asking for it... There are two stakes for a reason, aim for the first, end up at the second, using the paralax for reference.

Having your machine creating a snowball at 15ft with your landing spot below you is not my cup of tea, but if it makes you happy, have at it.

RH

[bell hater]

Originally Posted by jemax

"If it's more than 10 kts we dont fly, no problem"

How do you ever get anything done? Wind is your friend at altitude…. (Or worst enemy) Depending if it’s a smooth laminar flow or a turbulent gusty day

[Overt Auk]

Now no way am I an expert in this field (most of my mountain flying has been done without benefit of engine, which does at least teach you about wind appreciation) but:

I am worried by Arm Out the Window's reasoning. If, as he says there is a 'demarkation line' somewhere above the ridge where all is fine and easy, the first time that he is going to find out about conditions at the LZ is with 100' to go on a steep approach. Next time someone is showing me how to do it I hope they follow 170's pattern

OA

[Gomer Pylot]

I'm wondering if everybody is on the same page concerning the definition of steep and shallow. What is normal, perhaps a little shallow for me is steep to some I've flown with. Could we perhaps define our terms, with respect to the approach angle in degrees? I don't do mountain flying, but for offshore rig approaches, at or near max gross weight, high density altitude, what works for me is putting the pitot tube (in an S76) on the far edge of the deck, getting about 250 fpm descent, and holding that angle throughout the approach. This results in very little pitch increase at the bottom, and little or no flare, and doesn't cause the very high torque requirements I see with very shallow approaches (almost flat in many cases). I'm not sure what the actual approach angle is for this, but many pilots I've flown with do consider it steep, although I don't think it is.

[Arm out the window]

Re the 'demarcation line' - my understanding, simplistic as it may be considering the real world doesn't act like a textbook, is that the flow of air over a ridge or hilltop can act something like airflow over a wing; ie conforms to the curve for a while, and somewhere behind the point of maximum curvature, may unstick and become turbulent.
So, Overt Auk, if you crept up to the hilltop shallow or level from the downwind side, you would be in the turbulence and downdrafting. If you came in at an angle on the steepish side of normal going to a pad at the top of the hill, you should be out of it - if this concept is appropriate for the conditions on the day, of course. Or you could approach across wind if the terrain allowed, in which case shallow might well be fine too.
Naturally everyone can think and do what they want; it's just one way of looking at it that I think is reasonable under some circumstances.

[paco]

A very good point, Gomer. I use that approach for offshore and mountains for the very reasons you describe. It works for me, and dire prognostications of ending up in a ball of aluminium won't stop me.

Steep to me is where you don't have enough forward speed to fly away, rather than an angle as such. Shallow, as demonstrated to me by one guy in Penticton, is an almost horizontal approach at the top of the max continuous power range (when heavy), with nothing up the sleeve if you need it at the end and your collective already high if you get a problem, and not there to help you slow down, which is one mountain technique. The approach that 170' describes is called the eye-level approach there, and is what should be used to get set up, but having done all that, I still wait for my normal sight picture.

I feel that you have to maximise your chances of getting into your site in a hostile environment, with or without an engine, and using a shallow approach ain't part of it.

For those of you who are curious, I did the basics in the British Army, then flew in Scotland for four years, learning from a guy who had flown in Nepal for fifteen years. Looks like he was a bit if a rebel . They may be small, but Scottish "hills" will still kill you. They flipped Ken Kendal upside down in his 206.

The British Army teach the steep approach (or at least they did then) - the stronger the wind, the steeper you got. The Canadians teach the shallow one, but they got that from Okanagan. Go figure.

This is a demarcation line:



Phil

[JHR]

I start at a normal (8-10 degree) approach. If the wind is strong I shallow the approach, it seems to me the steep approach with strong wind causes you to desend with almost flat pitch. I don't like to pull collective/flare to stop at the bottom of the approach. I like to be powered up and slow for the last 1/4 mile to allow the approach to terminate in a stable hover with no big power application or flare to stop the forward movment.

[SAR Bloke]

Steep to me is where you don't have enough forward speed to fly away,

You can fly a climbing approach and still have enough power to fly away providing the power margin is good enough (good forward speed or updraughting air). Obviously the speed will have to decrease at some point but not until you are assured of making the LS.

I don't know about Army training but the RAF also teach the steep approach on the basic mountain sortie. There are times when this is appropriate. After the 'basic' sortie student are then taught advanced mountains which involves staying on the updraughting side wherever possible (you then don't need to worry about the nast demarcation line) and flying level (and climbing approaches).


One of the problems a discussion like this (rather like the steep/shallow comment) is that everyone has their own picture of a typical mountain approach but in reality they are all different. Are we talking pinnacle, ridge, valley , bowl, etc? What wind strength are we assuming? How much spare 'power' does your machine have? What is the weather? All these variables need to be taken into account. There is no one answer.

[170']

Is that the big one, from the Kala Pattar side Phil?

[170']

Let's get specific?

If you go thru a serious Mtn flying school, they have a specific type of SAFER approach for just about everything you’ll run into…

Paco’s photo is a clear indicator of a demarcation line. But with clear evidence such as this, there are still a lot of people who would stumble around trying to decide how to get in. Until they either abandon the job or feel they have to commit to the last thing they thought of, because everyone’s watching or getting pissed off with the delay….

It’s all well and good to say…Wait until another day? But what if every day’s the same

An interesting diversion is to ask yourself, if you could or would try get in, under the conditions imposed in Paco’s photo…

Try to imagine what the wind strength is, and is it all bad, all good, or (Yawn) just another day in the hills…

Imagine your task is to put out a crew to install a repeater site? At some point your going to need to sling some steel or aluminum, bagged concrete mix, water etc..

Forget that it’s at 29,000’ (I think?)

Imagine it’s 7000’

I’ll post my opinion in a few day’s if anyone responds!

This is NOT a challenge, Just a way we can all consider options, be it one or 100

170..I edited the imaginary height to a more common height, so more people can relate to it

[paco]

Well, the only good place to land looks to be behind the demarcation line! You could try into wind first of all, steep, and keeping just the rotors the right side of it - if you can see down the hill is about right. Maybe vertical in at the last minute.

If that wasn't comfortable, maybe look at riding the backlash on the lee side, but in that wind it might be a bit far away, unless you hovered in.

IMHO

Phil