Cobalt wrote:
My personal definition of severe turbulence is anything exceeding +-1G acceleration, easily measured by observing objects floating through the cabin before slamming to the floor a couple of seconds later. This is memorable enough – I still remember all three incidents (1×TCU, 2x just a very windy day).
I think of it as headsets flying off, heads hitting the top of the cabin, stuff flying around and genuinely struggling to get the plane under control.
As AnthonyQ has posted above there are definitions for turbulence. In my personal experience I had ‘extreme’ (i.e. uncontrollable airplane) twice, ‘severe’ several times and ‘moderate’ quite often. All of them to do with mountain ranges and/or thermals across deserts (that mix is actually the worst). None a pleasant experience, though….
My personal definition of severe turbulence is anything exceeding +-1G acceleration, easily measured by observing objects floating through the cabin before slamming to the floor a couple of seconds later. This is memorable enough – I still remember all three incidents (1×TCU, 2x just a very windy day).
Peter wrote:
Yes; I guess it was “moderate to severe”.
Peter while I am sure it felt uncomfortable. It looks like light to occasional moderate.
This picture was taken at ENOP one day. The wind and turbulence looked about the same as in this thread, and it shows what it’s like on the ground 
Yes; I guess it was “moderate to severe”.
The most interesting thing for me is that flying above that mountain to our left would have been smoother. Or maybe even slightly to the other side of it, where there would be an upgraught.
Where we were flying, there was a strong upgraught much of the time, which is the opposite of what I would expect.
Looking at the GFS forecast again for the time, the wind across the mountain might have been 70kt.
Bonjour,
all i can see on the video is maximum moderate turbulence. But I know it can be a scary experience, and pilots with little hard IMC experience can easily be scared, especially in very light planes. Severe turbulence looks very different though.
It’s probably worth people (re)acquainting themselves with Turbulence Reporting Criteria as stated in the AIM (and no doubt other places):
Peter wrote:
The Q I have is whether flying above the mountain ridge would have put us in smoother airflow.
Hard to tell, I’d say probably but not necessarily. What would have put you into smoother air would have been to either:
- climb
- fly further out over the sea (5-10 miles or so)
From what I can tell from your video and pics you were in the worst zone for turbulence.
It’s actually quite easy to visualize how turbulence over a mountain range behaves. Just go to your nearest little stream and watch water flowing over rocks. You will see that the most turbulent flow is shortly after it crosses whatever barrier (rocks) there is. If you want to see this even better, then pour some food colorant (harmless, water-soluble stuff) into it a little bit upstream. Makes for a great little lesson in fluid dynamics!
Archie wrote:
This is incorrect. Vb (turbulence penetration speed) has nothing to do with the yellow arc.
True. Yellow arc runs from Vno to Vne. However, there is a relationship between Vno and Vc IIRC. I believe Vno cannot be higher than Vc and Vc is used in specification of gust envelope. Which means that if you fly at the bottom of the yellow arc (at Vno), you cannot be flying at higher speed than Vc so the aeroplane can take at least 3,000 fpm gusts from sea level up to 20,000 feet. And 3k fpm is a hell of a turbulence.
As was said before here or in the other thread, specifications change. One just can’t take the current specification and draw conclusions for a 50 year old design.
PS: Sorry for the edits. It seems I’m done for today. After posting it I thought I had a brain fart just to realize later that I had it right the first time.
