AR-1 N923DJ Texas 15-12-18

thomasant

Member
Wasp, yes, of course. Just an old habit of saying it from helicoptering days.

Vance, thank you for your encouragement and support. I appreciate it very much.
 

Kolibri

FW and Gyros
It is interesting to note how someone has posted that the gyro ran out of energy high off the runway. This is pure speculation, and that is the reason I am not seen on this forum anymore.
thomasant, that "someone" was fara in his post #3. He spoke with you, so his reported details didn't come across like "pure speculation". I merely quoted what he posted:

I talked to the pilot. In fact he called me. . . . It was simple pilot error brought on by sudden unexpected wind shear and sink and gyro ran out [o]f energy high off the runway and sunk down hard.
As with WaspAir, your "practicing autorotations" also caught my eye. Did you mean engine-idle landings?
What was wind direction and strength? Any gusting?
What was your estimated AS and GS when you "
experienced a sudden loss of lift during the flare due to a possible strong wind shear, resulting in a vertical drop of about four feet"?
Do you normally begin your flares at 4 feet?

Thanks for posting with such candor, so we all can learn from what happened.



_____________
Along the grass runway here in Anahuac, there is a large patch of tall trees. With the wind direction coming from the West that day, there very well could have been some rotor coming off of the trees.
Interesting, AirCommandPilot, thanks.
Here's an overhead view of T00, and grass Runway 35.


T00.png.jpg



__________
So I would still advocate slightly higher approach speed during gusty conditions, to decrease the risk of drop ins from up high during approach, and then a more nuanced adjustment of pitch as necessary during the roundout and on touchdown.
Yes, loftus, I generally agree; such was also my point here, and in previous thread (although bizarrely uncomprehended by one in particular).
A moderate groundspeed is a form of turbulence insurance, which you can cash in if unused for wind shear by simply bleeding off the energy in your flare.


All landings -- even the greasers -- must absorb some degree of vertical energy.
During turbulent landing conditions, I don't roundout at 15-20' and I certainly don't attempt a vertical descent.
Rather, I prefer to quickly get to about 2' off the runway with about 10-15mph groundspeed.
Although Vance terms this as "
counterproductive" I disagree, as from there any microburst or wind shear or rotor or gust has much less potential effect.

For example, if I'm dropped or slammed in from only 2', my moderate forward motion reduces the impact angle from something near 90° to something like 45° or less,
yet 10-15mph GS is not so fast that it poses a touchdown danger even in a rigid geared RAF. (NOTE: I do not advocate normally touching down at 10-15mph in nonturbulent conditions.)

None of this is to meant to comment on or criticize thomasant's actions that day.

Regards,
Kolibri
 

thomasant

Member
Yes, I spoke with Fara after the accident, mainly to commend him on the split mast. I even sent him the email of the statement given to the FAA. So I am surprised that he came to his own conclusions regarding what I experienced. Anyway, you all have the details now. So I'm pretty much done with this thread. Stay safe my friends.
 

Kolibri

FW and Gyros
Stay safe? How could we do that?
You're Instrument Helo rated, as well as a Gyro CFI. You've some 3,400+ hours in rotorcraft.

I cordially ask that you make this an instructional example for us.
In retrospect, would you have done anything differently that day?
What can we learn from that day?

If nothing, then you leave us with the impression that sudden wind shear is an unrecoverable bane during gyro landings.
That your crash has nothing to teach us but that "sh*t happens".

Personally speaking, I cannot accept that.

Thank you,
Kolibri
 

WaspAir

Supreme Allied Gyro CFI
I've seen several mentions of "microbursts" in this thread and would like to add a comment on that topic. One should never let the "micro" part of that word give the impression that such an event is not a big deal, or that it should be thought of as survivable. I was the first responder at an incident, in which I saw a friend approach our airport in his sailplane when he appeared to be swatted like a fly, slammed down to the ground as if a giant hand simply smashed him from 100 feet to the ground in an instant despite 85 knots of airspeed and a 40:1 glide ratio. He suffered major, serious injuries, and the aircraft (a beautiful, strong, kevlar/carbon/fiberglass +6 g to -4g capable ship many times stronger than any gyro you can imagine) was destroyed. No general aviation aircraft has much chance of surviving a true microburst; adding a few knots before the encounter or powering up during it won't do it. Even fast airliners with massive turbine thrust at their disposal are still at risk of being unable to power out (see Delta Flt 191). In a gyro, your only hope is avoidance.

That's not to say that windshear or a healthy downdraft is unlikely, can't be anticipated or shouldn't be prepared for. Just realize that a real microburst is a different and much more terrifying beast. They have been known to flatten a whole stand of trees.
 

Kolibri

FW and Gyros
Thanks WaspAir, distinction noted. Not an actual microburst at T00 that day.
What seems to have happened to N923DJ was more like wind shear or a rotor over the trees just west of Runway 35.

Thoughts/comments on the gyro handling of wind shear are invited. Let's all learn what we can from this.
 

thomasant

Member
Thanks for elucidating this Wasp. Your insight is always great.

Kolibri, since you wish to use this as a learning example, I'll try and explain it this way. What I have seen during short finals is that sometimes the air speed is dropped inadvertently, which can happen during gusts, and also with power changes. The sudden sink in a gust is quite noticeable and the initial tendency is to push the nose down to increase airspeed if the speed had reduced. This is when the ROD increases quite rapidly. Of course, there is still enough height to prepare for the flare. However, in many instances if the rate of sink seems uncomfortable for me, I have the student initiate a go round. So IMHO, the air speed is a critical factor in a landing till the flare.

Now what happens when there is a possible reversal of airflow like in a wind shear or sudden gust? the lift component can change perceptibly and the only way out if in the process of flaring is to open some power and either cushion the landing, or go around. So the use of available power is critical. Again it depends. If the aircraft is heavy, the power may not suffice. If the shear is quite strong, the power may not be enough and the climb out can be sluggish.

What could I have done differently? I really don't know. The only action I could take in the situation was to open full throttle. The fact that all three prop blades sheared at the hub usually is a sign that the engine was revving high.

This type of event is rare and if one is able to power out, all is well. Otherwise, a simplistic explanation is called Pilot Error, where the pilot screwed up the landing.
 

Kolibri

FW and Gyros
Thanks thomasant for bearing with this thread for a bit.
I agree with you that
"air speed is a critical factor in a landing till the flare".
During your previous two landings, had you noticed any crosswind, gusts, or rotors?

From where you were, adding full power was clearly your only option, which you did. I'm sorry that it didn't save things.
I assume that you were at idle rpm, which added some lag time to realizing full thrust.

What was your estimated GS when you encountered the wind shear?

The prop strike seems a bit of a mystery.
What bent or broke upon initial impact? The keel boom? Mast? Motor mounts?

Had the prop not sheared away, and you had thrust command, would it have made any difference?
I.e., could you have regained air after the first bounce?

Thanks for these details,
Kolibri
 

thomasant

Member
Kolibri, I appreciate your interest in this accident and if it helps, I will describe things in a little more detail.

Being close to the coast, the winds at Anahuac can get strong and gusty. Normally that is not an issue during landings in the AR1 due to the high inertia rotors. I was practicing simulated power off accuracy landings across the RW, into the wind direction, which is possible and advocated. I've done this many times and it is a non event. Both previous landings were just fine.

During the third landing, my recollection is that things were fine till I was about four or five feet and yes, at idle RPM. Ground speed was normal, around 10 mph. In this situation, I felt like I was pulled down to the ground at a faster than normal rate. I opened full power. When powering out, normally it responds without problem and one can feel the climb sensation. Things happened very fast and instantaneously. I knew instinctively that I was going to touch down. When I felt the impact, which was significant, I heard the engine go quiet and I instinctively knew that the prop had stopped. There was the sound that I heard, probably of the prop striking, and I knew then that I was toast. I actually closed my eyes and felt the rotors impact and when I opened them again, I was tipped over to the right side.

The ground was a bit soft, and that helped dissipate some of the energy. The mast bent completely at the detachable junction and that actually saved me, as the aircraft did not completely roll over.

Regarding the question of going round without the prop shearing, yes I believe that I would have been able to go round even if it had bounced slightly. I have done this several times and also during instruction. As I said before, during landing, one needs to be always prepared to go round with power. The rest will depend on how the machine responds and any lag.

Of course, what Wasp described is a possibility when we fly and is quite rare, but it can happen.

I recollect the time when I was T boned in the car several years ago. A vehicle that was stopped at a stop sign started moving onto the road on which I was driving, which was through traffic. It was dark and I was driving at around 45 mph. I saw the stopped vehicle at the stop sign and as I approached almost abeam, the car darted forward. I swerved instinctively to the right to avoid being hit, but she caught me at the left rear wheel and I was facing oncoming traffic from the opposite direction. I swerved right and I felt my car begin to flip over. That is the period of time when there is nothing else one can do. As I flipped, there was a safety sign on the right side of the road that caught me and arrested my roll, and I came to rest on the right side of the road facing the opposite direction, but on all four wheels straddled across a ditch on the side, with the sign beneath.

Moral of the story is that we cannot avoid or prevent certain situations. In such instances, what can determine the outcome is the initial corrective actions when things go wrong. Sometimes we are still here for a reason, while many others are not so fortunate.
 

loftus

Active Member
m
thomasant;n1140980 said:
Thanks for elucidating this Wasp. Your insight is always great.

Kolibri, since you wish to use this as a learning example, I'll try and explain it this way. What I have seen during short finals is that sometimes the air speed is dropped inadvertently, which can happen during gusts, and also with power changes. The sudden sink in a gust is quite noticeable and the initial tendency is to push the nose down to increase airspeed if the speed had reduced. This is when the ROD increases quite rapidly. Of course, there is still enough height to prepare for the flare. However, in many instances if the rate of sink seems uncomfortable for me, I have the student initiate a go round. So IMHO, the air speed is a critical factor in a landing till the flare.

Now what happens when there is a possible reversal of airflow like in a wind shear or sudden gust? the lift component can change perceptibly and the only way out if in the process of flaring is to open some power and either cushion the landing, or go around. So the use of available power is critical. Again it depends. If the aircraft is heavy, the power may not suffice. If the shear is quite strong, the power may not be enough and the climb out can be sluggish.

What could I have done differently? I really don't know. The only action I could take in the situation was to open full throttle. The fact that all three prop blades sheared at the hub usually is a sign that the engine was revving high.

This type of event is rare and if one is able to power out, all is well. Otherwise, a simplistic explanation is called Pilot Error, where the pilot screwed up the landing.
Thank you very much for coming on and explaining everything in detail. As I said in my posts it was all speculation in the absence of first person reporting, and thankfully you walked away, so you are able to do so. My questions respectfully are - where there any signs in terms of wind conditions that could have warned you that a gust like this was likely?
Have a wonderful Christmas and safe 2019.
 

Kolibri

FW and Gyros
thomasant, thank you for recounting the incident for us, especially during the Holidays.
It's given me much to ponder.

I wish you a Merry Christmas, and a soon return to the skies.

Kolibri
 

Brent Drake

Gyroplane Instructor
I always do a power off landings when wind exceeds 15 mph. Lets chance of turblance affecting the lift close to runway. Almost always have much smoother landings.
 

Vance

Gyroplane CFI
I land with some power in turbulence so I have more rudder authority and more options if I find myself sinking or ballooning in all of the gyroplanes I fly particularly anything with a turbocharger.

It is not unusual to have a fifteen knot wind shear at five of the airports I regularly fly into; all are near the ocean and around 3,000 foot plus mountains. Santa Maria (SMX), San Luis Obispo (SBP), Santa Barbara (SBA), Santa Paula (SZP) and Camarillo (CMA). I have found this may result in an unanticipated sink during the roundout.

Recently as I turned final at SBP I experienced over a twelve knot head wind that became a seven knot tail wind during my round out. Wind was reported calm on an ATIS that was less than five minutes old.

During the round out I am consciously looking down the runway so I find it difficult to monitor airspeed.

I find the lower I get the faster the ground speed appears making my perception of ground speed inaccurate.

For me sight picture becomes the primary indicator of excess sink of ballooning up. I want to have a consistent
rate of descent.

So far I have been fortunate in the timing of wind shear.
 

Kolibri

FW and Gyros
During turbulence, the more I think it over the more I prefer my lower round-out at about 2' near the numbers.
From there I've plenty of runway to bleed off AS and rotor wash, and any wind shear I may experience will have little drama.
I then touchdown at a walking speed or less.

YMMV.

Regards,
Kolibri
 

loftus

Active Member
Kolibri;n1141018 said:
During turbulence, the more I think it over the more I prefer my lower round-out at about 2' near the numbers.
From there I've plenty of runway to bleed off AS and rotor wash, and any wind shear I may experience will have little drama.
I then touchdown at a walking speed or less.

YMMV.

Regards,
Kolibri
From 2' should not be a problem, it's getting to 2' safely I would think. Nothing that says the wind shear won't strike while you are getting down to 2' before the numbers. I guess the question is what is the safest speed, power setting and attitude to have in a gyro during that period when a sudden loss of lift may occur when one is higher than the aircraft can handle the impact. That's my question for all the CFI's.
 

Kolibri

FW and Gyros
Think of it from a shooting perspective: a 180gr/2700fps .30-06 bullet drops less over 200 yds than a 350gr/2000fps .45-70 bullet.
It's a matter of flatter slope.


______
Another thing to clarify is the distinction between loss of AS (from a subsiding gust) and actual downdraft.
While either will (unless sufficient power is added in time) result in a sudden loss of altitude, it's often more vigorous during a downdraft (thus one's AS must be higher, for a flatter slope as insurance).
Also, one could simultaneously experience a loss of lift from lessened headwind, and a downdraft. Perhaps that's what happened to thomasant.

Somebody in another thread (a gyro CFI, no less) opined that
"Down drafts from rotors don't go all the way to the ground and will not smack a gyroplane right into the runway."

When I disagreed, he snipped, "You are welcome to cling to your misconceptions that down drafts go all the way to the ground..."

thomasant experienced some sort of downdraft from 4', and it smacked him right into the runway.
At least that's the "
misconception".

Regards,
Kolibri
 

fara

AR-1 gyro manufacturer
This thread went lively during Christmas. Tony, sorry if I came across incorrect on suggesting pilot error. Wind shear can happen at any time, anywhere. A micro-burst is quite different and much more dangerous. I doubt you had a micro-burst there.

One should carry 1/2 the max gust speed to normal approach speed for safety in airplanes but I am not sure in rotary wing where there is no wing stall that quite applies the same way. There we need to worry more about getting on the back side of the power curve that will supposedly put us in a vertical descent at a given power setting.
Gyro CFIs can discuss this 1/2 max gust speed idea and try and justify how that applies to a rotary disc that supposedly does not stall.
 

Vance

Gyroplane CFI
According to Britannica: "Updraft and downdraft, in meteorology, upward-moving and downward-moving air currents, respectively, that are due to several causes. Local daytime heating of the ground causes surface air to become much warmer than the air above, and, because warmer air is less dense, it rises and is replaced by descending cooler air."

I should add another cause is running into a ground obstruction like a mountain or a building. There will be lift on the windward side and sink on the lee side. This is important knowledge for anyone flying in the mountains or in turbulence.

The air has nowhere to go as it gets near the ground because the ground doesn’t suck.

I personally find it comforting to know that down drafts don’t go all the way to the ground when I am in a 1,500 foot per minute downdraft and losing altitude rapidly despite wide open throttle.

I spend a lot of time with clients helping them to understand the wind and how it affects a gyroplane.

I recommend some time in a glider to help them as pilots to better understand the moving air.
 

Kolibri

FW and Gyros
I recommend some time in a glider to help them as pilots to better understand the moving air.
I agree. Having many times soloed in gliders, I think glider flying is a great prerequisite to any kind of piloting.

However, I remain amazed at Vance's assertion (first made elsewhere, and repeated in this thread):


Down drafts don't reach the ground because there is nowhere for the air to go.
I replied:

Vance, any downdraft with sufficient energy to reach the ground, will.
This is not restricted to merely microbursts.
He then wondered aloud:

If I am caught in a 600 foot per minute (6kts) down draft please tell me where the wind goes when it gets to the ground.

In a microburst it spreads in all directions as it collides with the ground because it is going much faster than 600 feet per minute.

This is pretty basic stuff and I cannot imagine why you refuse to grasp it.
Apparently, to him, unless a downdraft is at 600+fpm microburst velocity, it will neither reach the ground nor spread out.
????

Imagining that some satire might get through to him, I posted:

Maybe you're right.
I just tried to blow away a piece of lint on the floor, from 2 vertical feet.
I couldn't do it because the downdraft of expelled breath didn't reach the ground because the air had nowhere to go.
It's amazing how the air knew that, and stopped on its own.
Such was unavailing, as he just posted in this thread:

The air has nowhere to go as it gets near the ground because the ground doesn’t suck.
I personally find it comforting to know that down drafts don’t go all the way to the ground when I am in a 1,500 foot per minute downdraft and losing altitude rapidly despite wide open throttle.
Perhaps somebody else will have better success in explaining to him that a downdraft with sufficient energy to reach the ground, will reach the ground and then spread out laterally.
Perhaps he will then be convinced to give up his baffling and dangerous false comfort during 1500fpm downdrafts.
Perhaps he will cease misinforming gyro students on the matter.

Regards,
Kolibri
 

Vance

Gyroplane CFI
"Vance, any downdraft with sufficient energy to reach the ground, will.
This is not restricted to merely microbursts."

Of course it will reach the ground if it has sufficient energy. It just won't reach the ground as a down draft at the same velocity as it had high above the ground.

It appears to me that some people continue to confuse downdrafts with microbursts and imagine that a 600 foot per minute down draft with reach the ground going 600 feet per minute (6.8 miles per hour).

The National Weather Service has this to say about microbursts:
As it hits the ground it spreads out in all directions. The location in which the microburst first hits the ground experiences the highest winds and greatest damage. Wind speeds in microbursts can reach up to 100 mph, or even higher, which is equivalent to an EF-1 tornado!

As I calculate it a hundred miles per hour is 8,800 feet per minute.
 
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