Coming from High Sierra to Palm Desert, Ca. I had to fly by some small TS. I did not like it at all. The wind was also ripping in the Owens valley in the Sierra Nevada mountains.

So how do you know when it is to rough? If the wing comes off that is to much. I don't want to do that!

Cheers...Rob

When we left dead cow we went through truckee up the valley to Delano, glad we didn't go through mammoth pass, it looked rough. We had a 35-40 knot head wind the whole way back.

I would think the g-meter recommend by Brian ("Brian's Flying Book ) would be helpful. I have had dirt, from the floor, get in my eyes. Quite a bit of negative g. The positive hurts more but is not as scary.

Unfortunately / fortunately for pilots of low powered airplanes, turbulence generally accompanies good thermal and hydraulic lift. Without the natural heat of day energy, some passes are unobtainable.

I don't know how many iterations of data are necessary to prove downdrafts don't go all the way to the surface. I have a few thousand.

Fly at TAS below maneuvering speed (Va) if turbulence is an issue. Fly away from whatever is producing it: TS, terrain etc.

contactflying wrote:
I don't know how many iterations of data are necessary to prove downdrafts don't go all the way to the surface. I have a few thousand.

Jim, I've been lucky enough to make acquaintance with a few salty old pilots lately, trying to ferry my new plane from Calgary, over the Rockies, to my home airport on the coast. The weather has been impossible, but I've had some great conversations with seasoned pilots. In one conversation I was expressing my fear of downdrafts as a rookie mountain flying pilot. He said "Kid, even a strong downdraft doesn't push through the earth."

I have so much to learn;-)

As has been mentioned, sinking air cannot push the Earth out of the way. Just like dumping a bucket of water on the ground, it eventually splashes out in all directions horizontally.

Which means that if you fly close to the ground you will encounter horizontal winds from any and all directions, but not a crushing downdraft. The big downbursts that have crashed airliners do not push the airplane down into the ground, the airplane sinks into the ground because of the tailwind reducing the net airspeed below stall.

This example is for flat ground. When you throw mountains into the equation, everything is skewed and altered because of the interplay between vertical and horizontal air motion and terrain that is not at a right angle to the downburst.

As any proper engineer will tell you, the primary and most effective way to deal with turbulence is to reduce speed. Sometimes you need to go a little slower, sometimes a lot slower (even more than just reducing speed back to maneuvering or turbulent air speed). Sometimes, you need to reduce your speed to zero and put on the tiedown ropes.

When your picket hammer makes it's way out of the bag that's tied down and smashes through the back window, it's almost time to call it quits... I thought turbulence in Australia was bad, then I moved to New Zealand

My perspective (and tolerance) on turbulence changed somewhat after flying on Kodiak for several years. Visitors from New Zealand noted to me that Kodiak looks a great deal like NZ....in many ways.

MTV

From a structural perspective, as mentioned above, flight below Va will protect the airframe. Moderate turbulence will scare most pilots into taking other action (turn around, land, climb etc) long before turbulence actually reaches the SEVERE level. Instructing in Navy T-34's we trucked through A LOT of bad weather. Even at just MODERATE turbulence, there were times that you really couldn't read the instruments. At SEVERE, the airplane becomes uncontrollable for brief periods. You will KNOW if you are in SEVERE!

Jughead

Being queezy helps. The plane can take more than I can. As long as I seek refuge from the storm before I exceed my comfort level, my plane will be fine. I fly for fun, so there is no reason for me to push the envelope. I'm also retired so I can wait as long as necessary for conditions to align with my comfort level.

If you are below Va, remembering that Va decreases as weight decreases, the wing stalls before the G limit is met.

The airframe can take a worse beating than the pilot can.

But....

Some of the airframes we fly are 60+ years old.... So, there is an unknown element there.

Good topic Rob, I was always told the airframe can take more punishment than the pilot in turbulence, so far that has been correct. As mentioned above we get probably more than our fair share of turbulence down here.
I have different levels of comfort, there's the simple bang your head in the roof - you'd never fly anywhere here if you stopped at this level. Then there's the loose the headset, maps, seat pocket contents, followed by the plume of dust from the dash and surrounds that you had no idea was lurking within the inner workings of your panel. Then finally air so rough you cannot reach the engine controls or do much other than ride it out, thankfully I have not been past this stage so I don't know what comes next [emoji51]
I HATE turbulence, especially when you can feel and hear it coming and will do most anything to avoid getting a kicking up there.


Sent from my iPad using Tapatalk

OregonMaule wrote:So how do you know when it is to rough? If the wing comes off that is to much. I don't want to do that!

Cheers...Rob

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSAIB.nsf/dc7bd4f27e5f107486257221005f069d/3c00e5aa64a2827e8625781c00744393/$FILE/CE-11-17.pdf

Take a close look at this Special Airworthiness Information Bulletin that discusses Va. SAIB CE-11-17 was issued on January 18, 2011. It discusses some myths and realities surrounding Va. Here's what it has to say:

On November 12, 2001, American Airlines Flight 587, crashed shortly after takeoff from New York’s John F. Kennedy International Airport. The crash killed all 260 people aboard and 5 people on the ground. The National Transportation Safety Board (NTSB) determined “the probable cause of this accident was the in-flight separation of the vertical stabilizer as a result of the loads beyond
ultimate design loads that were created by the first officer’s unnecessary and excessive rudder pedal inputs." As a result of this accident and subsequent investigation, it was revealed that many pilots have a misunderstanding of what the design maneuvering velocity (speed), VA, represents. Many pilots believe that as long as the airplane is at or below this maneuvering speed, they can make any control inputs they desire without any risk of harm to the airplane. This is not true [emphasis added].

The design maneuvering speed (VA) is the speed below which you can move a single flight control, one time, to its full deflection, for one axis of airplane rotation only (pitch, roll or yaw), in smooth air, without risk of damage to the airplane. [emphasis added]


In other words, just slowing down 'a little bit' may bite us. We should slow down a lot and be VERY gentle with our control inputs. Some stuff I've read suggests the true Vturb (Turbulence penetration speed) is pretty close to Vy. That's a whole lot slower than Va. And it too will vary with weight. The formula to calculate our weight adjusted Va is: Vanew=((current weight/GTOW)^1/2)*(Va at GTOW). The formula also works for adjusting Vy for current weight.

Yeah, I don't do square roots in my head very well any more. I've found for my plane the reduction in Va (or Vy) works out to about 1 kt per 100 lbs under GTOW. Depending on your GTOW and airspeeds yours might be a little more or a little less.

NZMaule wrote:Then finally air so rough you cannot reach the engine controls or do much other than ride it out, thankfully I have not been past this stage so I don't know what comes next [emoji51]

This sounds like the Rakaia river just below the foothills during a good nor-westerly blow! That point when all you can do is hang on, and let the plane ride you through it. I really hate it too.

We have accelerators installed in our avionics, and I was surprised to see that the majority of really bad turbulence is seldom more than 1.8g.
The really (really) extreme events, the ones when you have to stop flying the plane for a few seconds just to collect yourself, even they have been no more than 2.2g in my flight experience.

Our airframe is designed for +4.5g and -1.8g, with a safety factor to +6.6g and -2.5g and that's when it's loaded to gross. So while I agree that the pilot is typically going to break before the airframe does, a very severe negative g-force is the only realistic danger to our aircraft based on the flying we do.

I always slow down when we strike really bad stuff, which reduces the acceleration the turbulence causes.

Did 2.5-3 hours in constant turbulence that was hitting a little over +2 on my g meter and similar -1

Not real fun when it's constant, for long periods and you don't get a break...

Then there is the occasional, out of nowhere, with no warning... head smashing into something inside the cockpit

I was sort of under the impression, if you keep your speed down, and weight reasonable, you have had enough turbulence, when you as the pilot decide you have had enough.... It's amazing how tough most of these planes are!

Thanks guys. You confirmed what I believe to be true.

Cheers...Rob

Just like dumping a bucket of water on the ground, it eventually splashes out in all directions horizontally.

In 1986, the gas boy at Jackson Hole suggested I fly NE, towards Cody, to see something interesting. A micro burst had leveled hundreds of acres of forest. Trees fell different directions and looked like a box of tooth picks were dropped.

180Marty wrote:

Just like dumping a bucket of water on the ground, it eventually splashes out in all directions horizontally.

In 1986, the gas boy at Jackson Hole suggested I fly NE, towards Cody, to see something interesting. A micro burst had leveled hundreds of acres of forest. Trees fell different directions and looked like a box of tooth picks were dropped.

Micro bursts can rip a forest of healthy trees out, I have seen it. We must be careful about what we read and other people's complacent attitudes when it comes to turbulence.

8GCBC wrote:
Micro bursts can rip a forest of healthy trees out, I have seen it. We must be careful about what we read and other people's complacent attitudes when it comes to turbulence.

Agreed.

Something I keep in mind when I fly through turbulent air is that the NTSB accident DB only has reported structural damage that resulted in either seriously bent airplanes, or people who wound up in a morgue or hospital. Lesser damage, or even major damage that was unreported isn't in the AOPA's Nall Report nor the NTSB db. My 54 year old, well maintained Cessna has experienced a lot of flexing from turbulence over 4600 or so flying hours. We all know that flexed metal eventually loses strength. The thing I think about is what that means for the design load limits (4.4 g positive and 1.52 g negative in Utility Category). Never mind the ultimate load limits that are 1.5 x 4.4g or 1.5 x (-1.52 g). If any of us get into ultimate load factor territory the risk of failure approaches 100%. There's an unkown, but non-zero probability that my aircraft, or any other that's accumulated significant flight hours or years of service no longer has the same structural resilience in turbulence as it did the day it rolled off the factory floor.

My "Too much turbulence" indicator is really easy, the Beaver's engine quits. Just for a little while, but it gets your attention.

I got into some really bad bumps three years ago, engine was quitting, my passenger caught the gallon water bottle on its way down from the ceiling, dirt in the teeth. I knew it was going to be bad when I went into the pass, but it was way worse than I imagined. I was actually having to work (which as we all know pilots are inherently lazy and don't like to work).

The next day, I was up and got into light chop, and my heart started racing....I was scared. For three or four days afterwards I was scared to fly.....my wife and I were "all in" with this business, and I was scared to fly, as Trent says "that ain't good". After a couple of beers one night I admitted to Trent that I was scared to fly, apparently that was all that I needed.

The next day I had a flight through what we affectionately call the Trench of Terror and when the bumps came I was fine, just needed a little beer and conversation to help.