Icon A5.. another crash Jul 27

X3 Skier said:
These discussion airspeed/tailwind/etc always reminds me of my technical mechanics course back in engineering school. We got a daily problem to work and if you got them right for enough days, you could skip the midterm or final.

The prof had a collection of doozies to “stop you at the Goal Line” as he said. One I had once was to calculate the relative speed of a bug walking on a rotating turntable in a train traveling down a track to another bug flying in a car moving 90 degrees to the the train track. I died on the one foot line. Taught me everything I ever need to know about relative motion as in this case, airspeed vs ground speed.

Cheers
Click to expand...


If it was on a tread mill, I know just whoooo to call!!!!
 
FastEddieB said:
And for newbies, there’s a thread for that!

https://www.pilotsofamerica.com/community/threads/stick-and-rudder-moments-redux.79699/

Worthwhile - at least before it goes off the rails.

I may go back and add “downwind turn in an Icon” to the list!
Click to expand...
BTW, the autopilot flying a wing low in a crosswind could happen if it was an older unit homing to a beacon (yeah, unlikely in a Cirrus).
homing.gif
 
I will note that will fuel fuel, the remaining useful load of the A5 is not very useful. Being over gross would be quite easy.
 
SToL said:
I'm not arguing that the aircraft knows what the ground is doing. Stop trying to say that.

The ONLY thing the aircraft knows is how fast the wind is moving over the wing.

In a headwind, it's moving faster. In a tailwind, it's moving slower. If the tailwind is significant enough, you will have to compensate for it, either by increased power, or increased pitch angle.
Click to expand...

Oh my goodness. Where do people get this stuff?

You say that you’re not trying to argue that the airplane knows what the ground is doing, and you make the absolutely true statement that the only thing the aircraft knows is how fast the air is moving over the wing, and then you completely go off the rails by making your last statement which would only be true if the aircraft knew what the ground is doing...

HOW can the AIRSPEED be different in a headwind versus a tailwind? For clarity, I’m using the generally accepted tems of headwind and tailwind as a steady state wind condition. If you are talking gusts, you should say so.

The aircraft is moving in and with respect to a body of air. The body of air may be moving with respect to the ground in a direction opposite to the direction of flight with respect to the ground. That is a headwind. If the body of air is moving with respect to the ground in the same direction as the airplane, it’s a tailwind. In BOTH cases, however, the airspeed is constant.
 
SToL said:
Let's say you have a 45 knot headwind and your airspeed is indicating 45 knots. You are effectively hovering.

Without making any changes to airspeed or pitch attitude, turn downwind, what's going to happen?
Click to expand...

Oh, I know!

You’ll still be flying at an indicated airpseed of 45 knots but at a heading 180 degrees from when you started. Your ground speed will go from 0 knots to 90 knots.

Next question?

[edit]
To be pedantic, You’ll probably lose a bit of altitude as well, because if you don’t make any changes to the pitch during the turn, your vertical component of lift, which will decrease as you bank into the turn, will decrease, and therefore, you will lose some altitude. Note that this has nothing to do with the wind, it’s just an aerodynamic fact of life.
 
Last edited:
The fun thing about a tailwind at low altitude is that you, many times, are using ground reference. Like that tree the guy hit. Ground speed goes up, tree gets bigger really quickly, but airspeed is still right at the stall. Brain thinks there’s plenty of airspeed to miss the tree because it’s been trained by so many into-the-wind landings that it “knows” it has available energy. But it doesn’t.
 
jimhorner said:
For clarity, I’m using the generally accepted tems of headwind and tailwind as a steady state wind condition. If you are talking gusts, you should say so.
Click to expand...

I did say that, in my very first response to palmpilot. And then it immediately went off into the 'relative wind' and 'steady state wind' argument.

I was merely addressing his comment where he stated;
↑
The only effect it has on an airborne airplane is to change the ground speed. Air speed is not affected at all.

I was specifically addressing wind variations, he was not.
 
It will be interesting to see what statements the NTSB gets out of the pilots.
 
SToL said:
I did say that, in my very first response to palmpilot. And then it immediately went off into the 'relative wind' and 'steady state wind' argument.

I was merely addressing his comment where he stated;
↑
The only effect it has on an airborne airplane is to change the ground speed. Air speed is not affected at all.

I was specifically addressing wind variations, he was not.
Click to expand...

The you should probably use terms like gusts and wind shear. Using terms like headwind and tailwind imply steady state, at least to most of the pilots I know. And your example of flying at an airspeed of 45 knots into a headwind of 45 knots and then turning downwind also seems to imply steady state, does it not? If not, what was the purpose of that scenario?

Now, if you asked the following question, then the answer would be different:

Assume an airplane flying at 45 knots airspeed into a 45 knot headwind. What happens if the headwind instantaneously becomes a 45 knot tailwind?

Note the word “instantaneously” in the above. That’s a gust, and terms like headwind and tailwind are usually understood to mean steady state.
 
jimhorner said:
The you should probably use terms like gusts and wind shear. Usng terms like headwind and tailwind imply steady state, at least to most of the pilots I know. And your example of flying at an airspeed of 45 knots into a headwind of 45 knots and then turning downwind also seems to imply steady state, does it not? If not, what was the purpose of that scenario?

Now, if you asked the following question, then the answer would be different:

Assume an airplane flying at 45 knots airspeed into a 45 knot headwind. What happens if the headwind instantaneously becomes a 45 knot tailwind?

Note the word instantaneously in the above. That’s a gust, and terms like headwind and tailwind are usually understood to mean steady state.
Click to expand...
A 90 knot gust is a tropical storm. Lol
 
SToL said:
I did say that, in my very first response to palmpilot. And then it immediately went off into the 'relative wind' and 'steady state wind' argument.

I was merely addressing his comment where he stated;
↑
The only effect it has on an airborne airplane is to change the ground speed. Air speed is not affected at all.

I was specifically addressing wind variations, he was not.
Click to expand...
Are you talking about Post #115?

I was responding to Post #110, which had no mention of gusts:
SToL said:
I disagree but open to learning something new.

Lift and airspeed both will increase with a headwind and both will decrease with a tailwind.

This is one of the simplest methods used to determine wind direction. Turns that reduce airspeed or require increased power, are downwind turns, where as, turns that increase airspeed or allow reduced power, are into the wind.
Click to expand...

We are in agreement that gusts can have an important effect on airspeed, at least momentarily. However, it looked like you were saying that whether you are flying upwind or downwind can also affect the airspeed. If so, I disagree with that (assuming the aircraft is out of ground effect).
 
FastEddieB said:
Watched the video twice.

1) Can anyone get a sense as to whether the takeoff was made into the wind?*

2) It seems all the pilot needed to do was to stay in “ground” effect for a while to let the airspeed build.
Click to expand...

It appears, from the waves on the water, the moving of the tree tops and the US Flag waving somewhat, that his initial power up was mostly into the wind, with perhaps a little right quartering headwind.

I wouldn't have waited so long to try to get up on the step, I would have initiated my takeoff run sooner and then turned into the wind. Not start if after I was in the wind on such a small lake.

I agree, stay in ground effect and climb out straight above the trees. For some reason he felt it a better option to climb immediately and turn downwind.
 
Let's put it another way, if it's easier to conceptualize for anyone having trouble with it. Again, steady wind, not gusty.

When you're in the air, and without any reference to the ground, there is no wind. No headwind, no tailwind, no wind at all, as far as your airplane is concerned. Because you are getting carried along with whatever the air around you is doing, it is effectively stationary as far as you are concerned.
 
Half Fast said:
Not as far as stalling, but it makes a difference in how much distance the plane traverses, which could be the difference between hitting or missing the trees. It looked to me like he banked to try to miss the trees and stalled, then clipped a tree.
Click to expand...

I saw that too, but it appeared he had a decent climb out, but as soon as he turned downwind he was struggling to maintain altitude.

I don't think he banked to miss the tree, I think as he raised the nose in an attempt to climb or even maintain alt, it made a very gentle stall "Just like the builders said it will", right wing low, until he stalled in right into the tree.
 
Matthew said:
Brain thinks there’s plenty of airspeed to miss the tree because it’s been trained by so many into-the-wind landings that it “knows” it has available energy. But it doesn’t.
Click to expand...
Apparently brain forgot to tell eye to peek at the AoA in this case. :)
 
SkyDog58 said:
Looks big enough if the proper technique is used.
Click to expand...
If it was big enough I don’t think the pilot would’ve needed to perform a takeoff sequence in the way he or she did.
 
Suppose the Icon is on a swift river flowing south at 10 knots and there is a tall waterfall 1NM downstream. The wind is 0 at 5 knots.

1) Which direction is preferred for takeoff?

2) Should the pilot drink a Keystone or smoke a joint before the attempt?

3) Which is better for cellphone video, the top or the bottom of the waterfall?
 
Half Fast said:
Suppose the Icon is on a swift river flowing south at 10 knots and there is a tall waterfall 1NM downstream. The wind is 0 at 5 knots.

1) Which direction is preferred for takeoff?

2) Should the pilot drink a Keystone or smoke a joint before the attempt?

3) Which is better for cellphone video, the top or the bottom of the waterfall?
Click to expand...

Trick question. Real pilots don't drink Keystone!
 
jimhorner said:
Oh, I know!

You’ll still be flying at an indicated airpseed of 45 knots but at a heading 180 degrees from when you started. Your ground speed will go from 0 knots to 90 knots.

Next question?

[edit]
To be pedantic, You’ll probably lose a bit of altitude as well, because if you don’t make any changes to the pitch during the turn, your vertical component of lift, which will decrease as you bank into the turn, will decrease, and therefore, you will lose some altitude. Note that this has nothing to do with the wind, it’s just an aerodynamic fact of life.
Click to expand...

And you’ll have to remove the up pitch when you level going the other way, or you’ll climb. :)
 
SToL said:
It appears, from the waves on the water, the moving of the tree tops and the US Flag waving somewhat, that his initial power up was mostly into the wind, with perhaps a little right quartering headwind.

I wouldn't have waited so long to try to get up on the step, I would have initiated my takeoff run sooner and then turned into the wind. Not start if after I was in the wind on such a small lake.

I agree, stay in ground effect and climb out straight above the trees. For some reason he felt it a better option to climb immediately and turn downwind.
Click to expand...

You know, he could have just aborted at any time during that. Did he have a PLANNED off the water point in mind...? Sigh.
 
luvflyin said:
Yeah. I get that. I understand it completely. But when there is a sudden change, unlike when flying standard rate circles, there can be. It doesn't last long. Read my post again
Click to expand...

I read it thoroughly, and it's still Inaccurate. There is no sudden change in airspeed when the plane changes direction to "downwind" in level flight with no change in power. None. Zero. Nada. The plane sees only the relative wind of its progress through the air mass. It has no knowledge of the wind speed over the ground. The act of banking requires some temporary nose up trim to maintain level flight (and therefore some decrease in airspeed to maintain level flight as long as the plane is banked) but that effect has no connection with wind direction; this would happen regardless of what direction you are flying. In a shallow bank this effect is relatively insignificant.
 
Ryanb said:
If it was big enough I don’t think the pilot would’ve needed to perform a takeoff sequence in the way he or she did.
Click to expand...

Icon says that the A5 only needs 920' to get off the water. You can double that to 1840' as a margin of error guesstimate due to choppy water, DA, and possible low pilot skill. Looking at the lake on Google Maps and using the distance tool, one can see that there should be enough room in more than one segment of the lake. If the pilot decided to use one of the smaller parts of the lake (my guess) or take off crossways, that is on him. My statement that the lake is big enough holds. But believe what you want.

Littlefield lake (2).JPG
 
asicer said:
Apparently brain forgot to tell eye to peek at the AoA in this case. :)
Click to expand...
When I was working on a simulated rope break in a glider for the first time, I was landing with about a 5-10kt tailwind. It was an eye opener about ground speed giving the illusion of air speed.
 
Matthew said:
When I was working on a simulated rope break in a glider for the first time, I was landing with about a 5-10kt tailwind. It was an eye opener about ground speed giving the illusion of air speed.
Click to expand...

And this is the crux of the matter for the "frame of reference mental block" that results in the downwind turn nonsense. Pilots can only see their progress via the ground frame of reference (apparent groundspeed) whereas the airplane flies via the air mass frame of reference (airspeed). The latter, most important reference frame, alas, is invisible, but no less real. And really important!
 
denverpilot said:
And you’ll have to remove the up pitch when you level going the other way, or you’ll climb. :)
Click to expand...

[Jokeing mode ON]

You mean all of that up pitch I was having to hold while flying into a headwind, right?

Yeah, that’s right, Now that I’ve made my downwind turn, the stick is pretty much all the way forward to keep from zooming upward.

Uh sure...






Sent from my iPhone using Tapatalk Pro
 
jimhorner said:
[Jokeing mode ON]

You mean all of that up pitch I was having to hold while flying into a headwind, right?

Yeah, that’s right, Now that I’ve made my downwind turn, the stick is pretty much all the way forward to keep from zooming upward.

Uh sure...





Sent from my iPhone using Tapatalk Pro
Click to expand...

You missed it. It takes some up-elevator in a turn or you'll descend. If you don't remove the up-elevator on rolling out of the turn you'll climb.

There is a small increase in AoA in a level turn, to carry the extra load factor of the turn.
 
chemgeek said:
...whereas the airplane flies via the air mass frame of reference (airspeed). The latter, most important reference frame, alas, is invisible, but no less real.
Click to expand...
It's only invisible if you ignore the ASI, AoA and stall indicator. ;)
 
Does the icon have a stall horn?
 
Yet for all we know this might have been a partial loss of power followed by a try to return to land event. Might explain the distance to get off the water.

If a partial loss of power did happen, I have no idea why the decision to still take off.

All a big swag.
 
Dan Thomas said:
You missed it. It takes some up-elevator in a turn or you'll descend. If you don't remove the up-elevator on rolling out of the turn you'll climb.

There is a small increase in AoA in a level turn, to carry the extra load factor of the turn.
Click to expand...

It was a joke. Geeze...

You see, first this guy said... and then I responded with.. and then another guy came in and made a joke based on the first guy’s incorrect claim, so I responded with..

Oh never mind. It’s way too much trouble to explain to the humor challenged who hasn’t been following the whole sub thread.

 
Last edited:
mondtster said:
Looks like it to me too. If anyone ever wonders why power on stalls are practiced in flight training, this is why. Sometimes the only safe option is to lower the nose and fly around the tree or through the tree line.

As far as the size of the lake goes, it looked big enough. It did however look pretty windy (rough water), and if they were heavy or the icon is underfloated it could have taken much longer to get up on step and out of the water than they expected. In turn, that could have put them closer to shore (and the trees) than anticipated.

It is amazing how much difference different floats and different weights can make on the amount of water needed to get off. I don’t have any experience with flying boats but I imagine it is similar.
Click to expand...

Hard to argue with a tree


Sent from my iPad using Tapatalk
 
Seemed to mismanage the wind a bunch. Word is he was a prospective buyer checking it out. Now the plane is trashed.
 
You must log in or register to reply here.
Back
Top