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-   -   Unintentional Flight Into IMC. (https://www.pprune.org/accidents-close-calls/637008-unintentional-flight-into-imc.html)

nevillestyke 24th Nov 2020 15:37

Unintentional Flight Into IMC.

Forfoxake 24th Nov 2020 16:34

Terrifying how quickly things go almost fatally wrong.

Two's in 24th Nov 2020 17:13

Originally Posted by Forfoxake (Post 10933871)
Terrifying how quickly things go almost fatally wrong.

There was nothing "quick" about that little fiasco. That went wrong when either clown A or clown B decided to ignore: the NZ AIP, basic airmanship and meteorology for Dummies.

Very lucky to walk away from that, and scud running up a Cumulus bank is not "Clear of Cloud in sight of the surface"

Big Pistons Forever 24th Nov 2020 21:16

The title of this thread should be corrected to Intentional flight into IMC......

ShyTorque 24th Nov 2020 21:25

That was my own thought. There was an early option to turn right, away from the cloud and from the high ground.

sycamore 24th Nov 2020 23:08

Feet seemed glued to the floor,slip-string all over the canopy......

Pilot DAR 24th Nov 2020 23:13

Well two pilots made a remarkable poor decision!

Feet seemed glued to the floor,slip-string all over the canopy.....
Yes, I think I heard the word "spin" in there somewhere, hardly surprising! I can't see any mitigating factor to excuse entering the cloud as they did....

But, I credit them with posting the video, that others might learn.....

ShyTorque 24th Nov 2020 23:21

From reading the comments under the video it appears that posting it in public was actually more unintentional than the IMC!

rnzoli 25th Nov 2020 07:45

According to a video review of the incident, the most important mistake was to fly above the cloud layer, assuming that the positive vario they experienced on the windward side will remain. What probably happened - according to the reviewing glider instructor - was that as soon as they flew above the cloud layer on top of the ridge line, they lost situational awareness, got drifted over the ridgeline into the sinking air, and got sucked into the cloud layer. They weren't expecting this and tried to descend out at the bottom, resulting in a dive in the cloud and at least an 8 G pull-up when they saw the ground. There was no spin, it was more like a warning that they they might spin, if they continue to climb back into the cloud.

That useful video is removed now, possibly in an attempt to widthdraw the original one from public view.

Less Hair 25th Nov 2020 08:00

Scary to look at. That's called instruction? Not many instruments for basic IMC flying are installed inside that cockpit.
Glad they survived it. Sharing it will help many others.

blind pew 25th Nov 2020 08:27

It was relatively standard to have a turn and slip in UK gliders.
Cloud climbs not uncommon with a specific frequency to avoid collisions.
Climbed in cloud triggered by a coal fired power station with 5 others in an divergently unstable glider..not a problem bar the mental stress.
The video appears to illustrate what happens with wave flying whether the system is set up from terrain or wind shear.
Unfortunately the behaviour of the atmosphere isn’t predictable which caught these guys out...reminded me of what happened to the AirFrance guys penetrating the ITCZ.
Like many I have been caught out but remember gliding records are incredible..endurance 57 hours, altitude 60,000? and distance over 3,000 km. It’s what happens as do the accidents flying in the french alps.

ShyTorque 25th Nov 2020 08:35

Cloud flying in good lift over a power station is one thing but I’ve never yet seen a coal fired power station sitting in the hills.

tartare 25th Nov 2020 22:41

That is an utterly terrifying video to watch.
The initial flight into IMC is bad enough, but the footage of the trees and hillside - man, that could so easily have been the last thing they ever saw.

Dan Winterland 26th Nov 2020 16:34

I was trying to read the g meter - it went to full deflection. 10g?

Cornish Jack 27th Nov 2020 09:43

Two thoughts/questions - Was the altimeter set to QFE or QNH and, when faced with the cloud bank what prompted the turn to the left ('the valley') rather than the clear air to the right?
... a supplementary - Would pilots in a particularly mountainous country not have a grounding in the peculiarities of mountain flying and associated Wx effects?

blind pew 28th Nov 2020 07:41

Cornish Jack
Basically NO.
I've been flying in mountains for 25 years after doing a unique weeks course with Jaques Noel who was the top professional mountain flying instructor. Part of every day was pointing out crash sites and how they got it wrong.
I am still learning about weather, orographic cloud, rotor and valley winds in spite of learning how to forecast 50 years ago and similar period observing from land, sea and air.
Altimeters are set to QNH for airspace and transiting goals between mountains. Displacement is purely on eyeball. Got caught out once as thought I was further away judging by the height of the fir trees until I could see the blades of grass having assumed that the trees were 60ft..in the upper slopes they are much shorter. The biggest danger in the french alps are wires followed by collision and lastly flying over colls where the air mass might be totally different and form a wall of cloud.
High G is used in gliders to avoid exceeding vne and flutter..used it once when low level aerobatics went wrong.
They are built far stronger than conventional aircraft..my first was tested to 12G.

FullWings 29th Nov 2020 15:18

What he said ^^^

Having watched the video a few times, thereís nothing wrong with the skirting of the cloud initially, as they have a clear route out into a valley. One does wonder why they didnít do some tacks in the lift to get above the cloud layer but I suppose that would have made it too easy.

When they turn left, it sets them up for a bad outcome, but they still had the ability to do a hard right and exit for quite a while. What I find incredible is that there don't appear to be any blind flying instruments in the front and judging by the unusual attitudes, in the rear as well. Even if they were in neutral air, it appears they would have gone into cloud, which leaves a huge ??? hanging over the whole thing. From the comments on the official NZ gliding site, it seem like one of those distracted instructor, unsure student scenarios where no-one really has projected the flight path forward.

If youíre going to flirt with cloud, you need a plan to get out of it, should the worst happen. Having some kind of reference is crucial as you will disorient pretty quickly, especially in turbulence. There are also occasions where, despite the best of planning, the weather changes and you have to do a cloud descent. If you donít have any instruments, you can do it on GPS (or even a compass) but that requires a bit of skill and mental discipline. Better to have a phone app for emergencies - I use iBFD in case of a double failure in my panel.

what next 29th Nov 2020 19:18


Originally Posted by FullWings (Post 10936902)
Better to have a phone app for emergencies - I use iBFD in case of a double failure in my panel.

That's better than nothing, but don't forget that this is not a real artificial horizon. The effects of turbulence and prolonged turns will make it unreliable in less than a minute. It can help to maintain level flight for a very short while but not more than that. The solid state accelerometers built into smartphones are just that: accelerometers. Not real gyroscopes. And it needs to be turned on and "calibrated", i.e. aligned with the horizon, before it can be used.

FullWings 29th Nov 2020 20:07

Not true for iPhones - they have all that’s necessary to create a full strapdown INS. I’ve had iBFD running for a whole flight including aeros and IMC and it was exactly in sync with my EFIS. That particular app I think was written by someone who writes software for instruments for a living and uses the gyros, accelerometers and GPS. If you don’t believe me, download it and try it - not expensive at £12. It’s not certified in any way but it’s better than a blank screen inside to go with the one outside!

I’m not suggesting for a minute that you should strap it to your yoke and take off in OVC000 and 75m but as something that is there for use in an emergency it could save your life...

Big Pistons Forever 30th Nov 2020 04:04

The part I found profoundly sad was the “just another day in a glider” low key and low energy conversation in the cockpit. Where this video starts was in an area where great care needs to be taken. Not dangerous per se but there should have been a steady dialogue about how the situation was developing and where the out was as well as some definite “no go” criteria spoken out loud.

The huge one is never fly over a solid deck that is just below you and never ever ever be in a situation where up air is required to stay on top. This goes triple when flying over a ridge. Ridge cloud can develop and/or move very quickly with a change in wind and.has to be respected, as well as the absolute requirement to maintain positional awareness so that you don’t inadvertently cross over to the lee side and get into sink.

Frankly I wonder about the safety culture of this glider club. I find it hard to believe that given the relaxed atmosphere in the glider, that guys where not frequently pushing the ridge lift around and over clouds.

Google “Normalization of Deviance”

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