Allot of idea's from allot of people, but when flying in big mountains that you cannot simply out climb in your SEP you spend most of the time checking behind you so you do not get trapped in that sort of rubbish. Keep the back door open at all times and always have an escape route in the mountains. Its simple any good mountain pilot will turn away from that sort of weather way before it becomes an emergency. Its not what you will do once you are in it, its what you will do before you are in it.

I found my time private flying around the South downs of England not as informative as my years commercial flying around the Southern Alps of NZ.:}

Difference between us. I think you've got the whole thing backwards, but I'm not the least bit worried. I care about how I fly, I don't care how you do it. :)

Yes. So why are you so upset then? "I only fly through valleys if I can see a way through", remember?

You read too many accident reports. Might be worth recalling that there are no reports written when that method succeeds. It is a rare exception that pilots don't make it out a valley one way or the other, so "most pilots" might be a stretch.

Putting the plane down is always an option. Pilots who disagree to that have one less tool to use to avoid becoming fatalities. It will most likely destroy the plane and it is not unlikely to result in injuries or worse, but it is an option. Lots and lots of accidents would have been avoided if pilots had used it. Difficult decision, yes, but flying isn't always easy!

Any sentence with an "always" in it is necessarily mistaken. The list of exceptions is endless; ice, high winds at high altitude, how do you get above MSA, how do you get back down again, what if MSA is higher than you can fly (oxygen etc), and so on and so forth.

I think a safe pilot should know more than one way to fly. :ok:

I seem to recall reading a magazine item a while ago that claimed the Antonov AN2 manual suggested when all else failed the aircraft could be stalled and mushed down to a safe landing. The claim being that in this configuration the aircraft will descend at a slow enough speed for the under carriage to be able to absorb the landing impact energy allowing those on board to walk away unharmed.

In the absence of a ballistic parachute this might be a strategy for bringing a light aircraft safely down to a valley floor where its handling characteristics allow if caught out in IMC. If the aircraft becomes VFR during the decent it could be flown on to a powered landing.

When I stall my C172 it will mush down at about 500ft per min which is roughly 5.7 miles an hour. Intuitively this sounds within the capabilities of the under carriage although I have no data on its performance specification to confirm this. Certainly I suspect there would be a better chance of survival from a vertical 5.7 miles an hour impact than CFIT into a valley wall at the typical cruise speed of 95Knots.

In poor weather there may well be a risk of a turbulence induced wing drop developing into a spin because there will be little or no control authority available to take corrective action to prevent it developing.

This kind of tactic if it works is I think a last hope attempt to manage down the risk of damage in an inevitable contact with the terrain.

"Inadvertent" IMC? - what a joke that is.

It is only ever really inadvertent at night and even then you can usually tell you are about to enter cloud if there is any moonlight or ground lighting at all.

Otherwise it is never inadvertent.

Our VFR only bonanza "pilot" will have had significant warning as the cloud filled in and should never have ended up in this situation. Cloud entry is almost never truly inadvertent from day VFR.

I would guess the poor schmuck doing the VT in the back (A) was not a pilot (B) had no idea he was nearly murdered by someone else's horrendous misjudgement. The tone of the piece is almost "beware mountains can sneak up on you" rather than "beware the murderous newbie PPL who wants to show off his new toy to you".

...I hope he learned from it - and after landing I hope he punched the "pilot" as hard as he could and vowed never to fly with him again ...

Sounds a bit low to me. I think I calculated that our Rallye had a vertical descent rate of about 15 mph in a full stall, and that is nicknamed the "tin parachute". Still 15mph is survivable and there is a story going around of someone running out of fuel at night in a Rallye and doing just that....

Don't forget though that when stalled you still have forward velocity, so could be travelling 30mph+ forward when you touch down.

I wouldn't fly around high mountains with "mountain obscuration" at the tops, when the MSA was > 9-10,000'. If the IMC was low down, say topping at 6k then I'd climb on top, or land...

The velocity, and thus the energy which needs to be dissipated, is the vector sum of the forward velocity (say 50kt) and the vertical velocity (say 5kt) i.e. slightly over 50kt.

In fact one could make the vertical velocity zero - by pulling up a bit at the point of impact. But that still leaves the whole forward velocity to dump.

If you do this at an airport, it's called a landing :)

The other thing is that few GA planes will be long term stable in roll, especially if there are significant roll disturbances. So, loss of control in IMC will rapidly result in the "spiral of death", unless the pilot does something reasonably sensible (like keeping wings level).

I gather some flexwing microlights are stable in roll and upon IMC entry one could just take one's hands off and the thing will descend with wings level, but GA spamcans won't do that.

I agree with SB there is probably no such thing as inadvertent IMC entry, but psychology is a big factor in this, and people do press on into poor vis which then becomes poorer vis, etc. Nobody likes the idea of turning back.

If you read the comments below the video, the Youtube poster and the guy with the video camera have made comments.

They are simply (3) friends of the guy having a ride in the L-39 and went in the Bonaza to film their friend, non of them are pilots. I assume they did not know the pilot of the Bonaza either.

The video has been posted to clearly show the idiotic behaviour of the pilot that nearly killed them. They have handed the video onto the FAA to be investigated.

This rather older one is pretty amazing too. Thread here.

I recall when the pilot first wrote about it in the Socata TB user group, c. 2006. From there, it "escaped" into the wild somehow...

Good point about the forward velocity.:ok:

Treating this as a simple right angled triangle in a straightforward parallelogram of forces. Square of the vector for the decent path of the aircraft will be the forward vector (stall speed) squared plus the vertical decent rate squared. Which is (50 x 50) + (6 x 6) = 2500 + 36 = Therefore the speed of impact at touch down is SQRT2536 = 50 mph. :uhoh:

Clearly it’s the forward velocity that is the dominant factor no matter how slow the decent rate as result of mushing down in a stalled configuration. The more the forward velocity can be reduced the lower the impact speed. Even if were possible to get the forward velocity down to the 6 mph of the decent rate the impact speed will still be around 8 mph.:ooh:

It looks like the key to making this manoeuvre work is to reduce the forward speed as much as possible by increasing the depth of the stall, turning into wind or maintaining enough control authority to flare before touchdown.

In a confined space of a valley turning into wind isn’t an option so there may be well be additional speed if there is a tailwind.:bored:

I'm not sure you have the whole picture here. The aircraft's crashworthiness may well depend on what hits first, and a high rate of descent with low forward velocity might not be the best configuration for survivability. If you are genuinely stalled there is of course no possiblity of a flare. Mushing down in a stalled condition the rate of descent is quite high. It might be better to wipe off the undercarriage with some forward movement and a lower rate of descent. Any engineers here who could clarify? Any pilots here who actually do mountain flying in a serious way? Or are we all just guessing?
So far I see no-one suggesting a parachute for the pilot. Of course, I wear one when flying a glider, in France it is actually a requirement. Problem is, when we are scraping along a ridge at 8000 feet amsl we often only have about 50 feet clearance at the wing tip, and not a lot more underneath. We do take _VERY_ great care to stay VMC. Which is probably the way to go with less than two engines anyway

High mountains and IMC don't mix unless you have 4 turbofans, and 400 seats on-board and are 30,000' above ;)

I think the best option is to remain flying until touch down. Physics says that as long as you don't decelerate too quickly (i.e. hit a tree) then you can probably walk away. I seem to remember a Indy Car driver experiencing 130G in an impact and he walked away, a bit bruised but ok. You need a relatively short distance to decelerate to pull less than 9G. 25m landing "roll" at 40 kts will pull 8g if my high school physics is correct -easily survivable - some people do this for fun !

The basic point is that no matter what you do, you can't fly slower than Vs.

The ground contact will always be made at a speed around that figure, at best.

I once read, from a famous aerobatic champion, that upon entry into IMC one could enter a flat spin and spin all the way down through the cloud. Presumably he would have intended to recover below the cloud... otherwise it's true his forward speed would have been low but what about the vertical speed? Maybe that is quite low as well - not something I want to try in the TB20 :)

In general, the term "mountain flying" is intended to mean flying in the canyons. Often this is done with the tops shrouded in cloud. This is done a lot in the Alps, where you have huge valleys with flat bottoms, and often the cloudbase is thousands of feet above the bottoms. The pilots that do this are trained to know the area well, and to not enter valleys which are a tight dead end, etc.

I would not do any of that - I fly straight across the top at FL160-190.

If you can simply stall an aircraft to a safe crash landing then Cirrus have wasted an awful lot of effort attaching effin great rocket-propelled parachutes to their aircraft and using impact absorbing undercarriages and seats to cushion the crash. I bet they wish they'd just tried stalling it in first.

unless you have a 40 kt headwind ;)

I have a reasonable level of experience of flying in mountains (well high ground!) in IMC. The point is at what height does the IMC start?

It is entirely possible to fly across high ground VMC below a solid ceiling. It needs to be high enough and you need to really, really know where you are. But it is very commonly carried out.

The 'received wisdom' seems to be if you enter IMC you climb and get above safety altitude. Well nice idea, but reallt difficult to achieve.

If you end up in a 'dead end', the chances of outclimbing the terrain are pretty poor. Most light singles struggle to get 1000fpm - as a gradient it might suit railways, to outclimb the average hill it is completely inadequate.

If you run out of VFR conditions you have a very short time to decide whether you throw the dice and hope you are flying up the valley whilst you climb or you force land.

A forced landing up a hill can result in a ground speed of virutally nothing. fly up the slope, hold off and then land - the ground spped if carried out well is virtually nothing

I have a reasonable level of experience of flying in mountains (well high ground!) in IMC. The point is at what height does the IMC start?

It is entirely possible to fly across high ground VMC below a solid ceiling. It needs to be high enough and you need to really, really know where you are. But it is very commonly carried out.

The 'received wisdom' seems to be if you enter IMC you climb and get above safety altitude. Well nice idea, but reallt difficult to achieve.

If you end up in a 'dead end', the chances of outclimbing the terrain are pretty poor. Most light singles struggle to get 1000fpm - as a gradient it might suit railways, to outclimb the average hill it is completely inadequate.

If you run out of VFR conditions you have a very short time to decide whether you throw the dice and hope you are flying up the valley whilst you climb or you force land.

A forced landing up a hill can result in a ground speed of virtually nothing. fly up the slope, hold off and then land - the ground seped if carried out well is virtually nothing.

You do need practice at landing on steep gradients - but once you have that you will neverr be able to understand why airfields are on level ground. The gradient makes an enourmous difference - you can literally park on a hillside. Getting the aircraft will need a helicopter but you will step out and walk to a phone (so long as you have sensible footwear and clothing!).

It would be great to simly fly over the top - but my aircraft does not have the ceiling or icing protection to allow that. I can fly through the valleys - it needs care and occasionally needs the odd U turn. Going IMC, when a precise heading is necessary - probalby with a turn, is all that stops contact with cumulo-granite is not a smart move, I'll land!

Is this actually ever done? I don't know... I would expect the thing to be written off if it cannot be retrieved with a tractor etc.

If I ever find myself inadvertent IMC in a valley, in the mountains, I'm not sure that aircraft retrieval post crash is going to be high on my list of concerns! :)

Safe flights.

Sam.

The only thing more dangerous than showing off is amateur filming of another aircraft in flight.

This was the root cause of the idiocy. All their attention was on filming the other aircraft. Like towing a water skier with everybody looking astern.....

Actually where I live aircraft are either recoveed by helicopter or stripped by 'walkers' and others.

The point is that your priorities should be the fragile tissue and flesh. Sometimes it is difficult to get to the nub of it but - a low speed forced landing or even crash if carried out under marginally forced conditions is a hell or a sight better than smashing into granite at 100 plus knots

Never inadvertant IMC
 

A C177 was caught in downdraft which it could not outclimb, flying south from Inverness in the early 90s. It was VMC on top, 7500'? but was pulled down, into the 6000'? cloud, and below the summit levels. After sighting rock off the wingtip, it hit an updraft, and was carried back up. PPL/IMC and CPL/IR?/Instructor cancelled flight and returned very shaken to base. No accident so no AAIB report. There was a description in the then HAC Newsletter.
Cloud can form suddenly when a packet of moister air rises as it meets rising ground, giving an unwary pilot inadvertant IMC.

For him to get pulled down by 1500ft you'd be looking at a wind speed of at least 15-20kt (-500fpm assumed).

Not a lot.

In my 'back yard' there was a G115 which went into a loch on a windy day - weather was IMC above the tops, below them very active. so active that even ground effect did not seem to say them (instructor and student).

Less of an IMC issue - but when the wind is blowing the ceiling can be very variable. The wae effect can result in a classic 'box canyon' situation - where it is either a 180 degree turn or a froced landing.

But the critical aspectg is than you have seconds to decide to keep flying or force land. And generally we do not force land.....

I checked the stalling and mushing down this afternoon to make sure I had not been over optimistic about the decent rate.:confused: This was with a French manufactured Cessna 172H.

Heading into the prevailing wind with the stall warner at full voice and an indicated airspeed showing 40 Knots over several runs the aircraft mushed down at between 500 and 600 feet per minute.:O

When decending in this configuration the aircraft was not directionally very stable. If this was attempted in a narrow valley I believe there is a good possibility of drifting into the valley sides since directional control was minimal.:eek:

Yes, at such low speeds the controls don't work well.

And a level turn increases the wing loading and increases the stall speed, so it is extra risky.

But, the faster you go the greater the minimum achievable turn radius, so if having to do a tight 180 it is better to slow down.

Totally impractical suggestion: With a hammerhead you could make a 180 degree turn no matter how narrow the valley is... :ok:

Told you it was impractical!

You could also make a very tight turn if you had room below you, to unload the wings during the turn.

Needs an understanding of how the stall speed depends on wing loading.

It's a good tactic for flying tight turns onto final (scares the passengers though :) ).

I suspect this was a power on stall/mush scenario. If you add another 20% to your forward speed you now have lots of control and minimal vertical speed (so the net total deceleration is about the same - but in a direction your body can stand much better). Also, flying rather than mushing you have a much better chance of arriving wings level and skidding over the rocks rather than catching a wing and cartwheeling.

Clearly you want to land along the surface going slow, rather than into a cliff going fast ... but 'stalling it in' seems to always be a worse answer than flying it in.


Also, when you hit the ground you want the engine at low power/off so when the prop hits something it doesn't rip the engine out and then chop through the cockpit before it stops running. This means there is a last second chop of the power (and consequent drop like a rock) necessary when stalling it in.

In terms of landing in a short distance, unless I have made a mistake, an approach at 60 knots is about 30m/s and with a 5g average deceleration, that would take about 30 feet to crash in (about 1 airplane length!). Well achievable if slidding up a hill.

I'm quite shocked at this thought of stalling the aircraft into an upwind hill.

And even if you did impact the hill at only 40 or 50kts (hopefully wings level) and survive, what then? Every American movie that has a car chase concludes with the Mustang plunging off the side of the cliff for at least about 800feet before it burts into flame.

Best idea is to utilise less Superhero Biggles skills, and decide earlier to turn around before you reach such a limiting position.

And before that, fly up close to one valley wall, ensuring that you always have turning room available to get out. Better yet, do a course in mountain flying.

A hammerhead (or stall turn as it's known here) still requires approximately two wingspans. Whereas a half cuban eight or an immelman (or something inbetween those two) requires only one. Theoretically. :ok:

Yeah, I know. Impractical anyway. Better use your superior judgement to avoid needing to use your superior skill and all that.

C172 pitot has a large position error at low speeds.
DO.

For some reason it looks like people well versed in mountain flying are the ones that chicken out first turing back/staying on the ground etc IMHO.

I´ve seen people from far away set off VFR in cloud capped valleys in alpine terrain, in condtions when local pilots that know the area well would stay on the couch at home! Some also set off after having been warned by said couch wearing pilots that conditions might not be suitable for flight. :ouch:

Some only made it after a certain amount of help from ATC after going IMC and climbing to continue IFR. (Why not IFR to begin with? I guess the 0-isotherm below MSA was a factor)

I would not like to be a passenger on a C-182 doing a climb from abborted VFR on the 100ft valley floor to get above the 5000ft peaks in IMC. Hope they had a good GPS with terrain info to assist on the way up! :sad:

On that we can agree - and also how NOT to fly :E

The whole issue with flying in mountains is that conditions can be changeable - very changeable.

It is by not means unusual to find the 'ceiling' is highly variable and what was 'fat and happy' one moment becomes very difficult the next.

I have never had to force land up a hill - but I know how to (from practicing on a very steep runway) and if the options were an aerobatic manoeurve or a force landing it would be an interesting decision.

However we have real evidence of aircraft in this area successfully forced landing with no injuries, simply by pulling up when the 'pilot' spotted cumulo-granite.

Never flying is a very good way of avoiding these hazards - sizeable detours is my preferred tactic, but forced landings do work.

As for quoting movies for the outcome of any course of action?? Strangely most of these vehicles usually catch fire before they hit anything. Scouting for locations with a clear drop and convenient camera locations (and clearing up afterward) costs the film production companies a fortune - no wonder they try and spice things up a bit!

Indeed, and such knowledge is why seasoned mountain flyers tend to add a little safety margin VX wise.

9999 -RA BKN025 Q1013 TEMPO 7000 RA

That's quite OK for VFR in the flatlands, not so much in the mountains IMHO

One should also consider the fact that you loose the horizon when flying in alpine terrain capped with clouds, and that has caused some disorientation for pilots in the past.

Indeed, and here's why:

:D

especially as those conditions are probably a warm front which will have tops ~ FL250 so no way to reach VMC above.

I keep meaning to fly to Trondheim, but most days can't even see Norway on the MSLP chart, under the collection of fronts :) And if it looks OK, finding clear weather a day or two later is much harder.

On clear days the views must be stunning but I'd imagine one gets only a small # of opportunities during the year.

I am a great believer in flying straight over the top of mountains. FL180 takes one ~ 7000ft above the main bit of the Alps and that should be OK with winds of about 30kt. The other day I flew over the middle bit of the Pyrenees at FL140 and about 5000ft over most of the terrain and while the wind was 35kt there was practically zero turbulence (I was quite suprised).

I heard a story from an well known Vietnam war ace who was flying safety pilot for a cross country voyage with an underage kid (one of those publicity stunts done several years ago before one kid got herself killed). He had to use an immelman to extract his charge after she flew her 152 into a box canyon. It worked, but only because of his superior flying skills - he headed the top gun school at one time in his career. I wouldn't recommend trying this one at home. BTW - he told me that flying with the kid was the dumbest thing he'd ever done in his flying career. :ugh:

We are missing the point. The thread talks about inadvertant entry into IMC. Okay as one poster said "how can you inadvertantly enter IMC in daylight" well you could be in the cockpit head down writing only to look up and only see white! But maybe unwillingly is a better description deciding to take to the clouds and climb. The lesser of two evils?

But this thread is about being in cloud not under it.

In that situation you cannot just land unsure whether you are descending into cumulus granitus.

You may climb straight ahead if you are pretty damn sure you are flying up a valley. I still hold that in cloud surrounded by hills your best option is to climb in a spiral trying to stay in one place. Even throw the book away and steepen the bank to keep the radius tighter its not that difficult for a competant IR pilot.

There maybe hill slopes either side but remember they are slopes so the higher you go the wider the gap to the hills.

This is a desperate solution to a desperate situation and minimises your chance of hitting terrain it doesnt eliminate it.
If anyone has a better option for IN CLOUD I would love to know what????

And yes you do have to be good on intrument flying and have good situational awareness.

Pace

Spiral climb
 

With the surface of the lochs calm and reflecting, I hit moderate turbulence at the east end of Loch Sheil on Monday. There was a strong updraft at one point at the side of Loch Affric. I'm not an instrument pilot, but suggest those considering the spiral climb try it under the hood, with a safety pilot, at a safe altitude, in turbulence. Especially if using steeper than usual turns. (A GPS will enable you to download your track, and see if you kept clear of a virtual hill)
Winds in the hills are unpredictable, and it won't take much to put you into a ridge. Turbulence is usually present somewhere. Often enough to make me (VFR) restrict speed and manoevering.
Staying out of cloud, unless you are at safety altitude, is essential.