Windshear

[turboplanner]

Just found the perfect example of windshear on a light aircraft.

One of my CFIs was killed by windshear.

I've experienced it twice, on late final around 50 to 100 feet above ground level.

The first time, I didn't react, just sat there and the Instructor slammed the throttle wide open so we missed going into scrub.

The second time, the CFI yelled "FULL TROTTLE" but I'd reached the end of the throttle sector and we went up like a lift.

You dont need to know the theory of it; when you fall it's just WOT and THEN fly it.

I timed this one at about 3 seconds from the point where he would notice the drop to touch down

In my cases I hadn't reached the runway; I counted 1.5 seconds from the time he would notice the drop to the time WOT would have arrested the drop and he could climb out.

You can put your stop watches on it and feel how much time you have to react.

 

We've talked in the past about building some actions, like EFATO initial response into muscle memory, where the average person starts to move in about 50/100 of a second, people with full currency and active about 20 to 30/100, and some down to 15/100.  If it's not a built in response; if something happens out of the blue, the reaction time will be around 2 to 5 seconds or even longer if you are disbelieving of what's happening. 

 

This is a good one to concrete in your head. Remember, I had made countles approaches and landings, but the first time, I would have started to respond after I hit the ground.

 

Windshear

Edited January 20 by turboplanner

[facthunter]

Wind shear near the gound is hard to predict and can have wide ranging effects . We are going to have to deal with more of this as the weather seems to be becoming more extreme more often.  A  gusting wind change associated with a sea breeze  or cold front is common in some places. Hit the Power and loosely hold the attitude. Do NOT chase the airspeed. IF you have been lifted UP chance are you go down soon. Be ready for it. Downburst from nearby storm s used to cause Jet losses till the training changed for late approach situations. MAX power is the first action. If you are interested there's a lot of info on reaction times  on engine failures at about V 1.( go or stop). where it's very critical..  Balanced field Length. Nev

[red750]

I remember my only experience with wind shear, back in the early 80's. I was in a Beech Musketeer on short final to Rwy 35 at Moorabbin, with my uncle, brother, and brother-in-law on board.Suddenly the bottom dropped out beneath us. My instructor had really pressed home - "If you get in trouble, throttle full forward and hold level to build speed". It kicked in automatically and we went around and landed safely. My B-I-L was white as a sheet, and talked about it for years.

[BrendAn]

runway 03 at traralgon has regular windshear when the breeze flows over the trees on the east side . 

scary stuff when you hit sink like that.   

 

[facthunter]

It has to be an instant response or you are in deep trouble. No 1/2 measures. Trees  and large buildings etc  cause mechanical turbulence, and is not as severe Generally but off-putting if you aren't  ready for it. Just increase speed for that one and go around if it gets pear-shaped. Nev

Edited January 20 by facthunter

[facthunter]

We will inevitably experience these things if we do much flying. Light wing loaded stuff is more difficult to handle in these circumstances..( Hard to keep it on the ground)  Spoilers save the day sometimes. Not available generally..  The main thing is to keep control  and don't be shocked into doing nothing, and becoming JUST a passenger.   USE  all of what you have going for you..  Nev

[Moneybox]

I had the bottom drop out just as we were approaching the end of the airstrip to land. I don't know the height we were at but it was too quick to react and we seemed to stop in ground effect at a nice level to land however we were still over the grass on the approach. My instructor hit the throttle and said go-around. We did but I thought what a waste of a good landing all I had to do was add a bit of throttle to reach the threshold 🙃

[turboplanner]

31 minutes ago, Moneybox said:

I had the bottom drop out just as we were approaching the end of the airstrip to land. I don't know the height we were at but it was too quick to react and we seemed to stop in ground effect at a nice level to land however we were still over the grass on the approach. My instructor hit the throttle and said go-around. We did but I thought what a waste of a good landing all I had to do was add a bit of throttle to reach the threshold 🙃

The guy in this video also has the wind shear in a very convenient position allowing him to convert to a landing but where the wind shear starts is random and I’d say your instructor took advantage to teach instant reaction and flying the aircraft out of trouble.

[facthunter]

Yes the Ground effect can be a bit of a life saver if you stay in it. Hot air over a sealed strip can let you down too. Air density is less. Makes for HARD landings. Nev

[Moneybox]

The one local guy that flies out of here said to avoid the heat. I guess that means to stay ground based in the summertime. I've just been outside pouring concrete. I ran out so got another six bags of quickset from the Cue Emporium. I was having trouble getting it evenly mixed in the concrete mixer so I decided to read the instructions. It says 'Sets in 5-15 minutes'. Right now it's 40.5° so most likely sets in 3 minutes. Anyway nine bags of cement and I'm done, the job is done too but I guess this is the sort of day he suggested I stay on the ground. It's forecast to hit 45° by Friday.

[facthunter]

It's no fun flying in the heat for a lot of reasons unless you climb up a bit but Planes don't like climbing om hot days. Nev

[red750]

 Filmclip from Facebook.

 

 

[skippydiesel]

Terminology question:

 

• Is "windshear" the same as "downdraft" same as "microburst"?
• If not, what is the difference?
• If technically diffrent, what are the practical (effect on aircraft) differences?

😈

[facthunter]

Do you have ANY IDEA How long it would take to explain THAT properly? IF you really don't KNOW you are a rather lucky Boy that you haven't found out the Hard way. I suggest you brush up on it because it's only getting worse with some of the weather the World is getting.. It's a HAZARD to all forms of aviation.  Nev

[Ando]

5 hours ago, skippydiesel said:

Terminology question:

 

• Is "windshear" the same as "downdraft" same as "microburst"?
• If not, what is the difference?
• If technically diffrent, what are the practical (effect on aircraft) differences?

😈

A sudden wind change (decrease in headwind,or increase tailwind) rob you of speed and lift (undershoot windshear)

[facthunter]

 Windshear is the difference between freestream at Height and ground level wind velocities. You'll notice on a  x wind approach the  Crab needed to stay on the Centerline "should" reduce (a bit) near the Ground..  Nev

[skippydiesel]

2 hours ago, Ando said:

A sudden wind change (decrease in headwind,or increase tailwind) rob you of speed and lift (undershoot windshear)

There were3 main parts to my question;

• Is "windshear" the same as "downdraft" same as "microburst"?
• If not, what is the difference?
• If technically diffrent, what are the practical (effect on aircraft) differences?

"Undershoot" -? meaning to land short? may indeed be part of the last question. I assume that the other effect might be an "overshoot" land long?

😈

Edited 4 hours ago by skippydiesel

[facthunter]

WE have progressed beyond that . It's not a good  "Terms of Reference" base. 

  Undershoot means any  THING  that would  ACT to make you land short.   We can Collectively work our way through this, but if you are not careful, some confusion may result which WE do NOT want. Nev

[Ando]

15 minutes ago, facthunter said:

WE have progressed beyond that . It's not a good  "Terms of Reference" base. 

  Undershoot means any  THING  that would  ACT to make you land short.   We can Collectively work our way through this, but if you are not careful, some confusion may result which WE do NOT want. Nev

Yes your absolutely correct in saying 👍

[red750]

I had an experience similar to that depicted in the clip. Fortunately I was a bit further out on final to rwy 35 at Moorabbin. This was late 60's/early 70's. Hadn't had my unrestricted PPL very long.

 

I had taken my brother, uncle and brother-in-law on a short local flight, their first flight in a GA aircraft, a Beech Musketeer. We had turned onto final, and were at about 300 ft when the bottom fell out of everything. I remembered what my instructor had impressed on me, and applied full throttle, but held the plane level, overflying the runway level to the ground as I built speed before attempting to climb and slowly retract the flap. Go around and try again. There were a couple of white faces on my passengers.

[Ian]

3 hours ago, facthunter said:

 Windshear is the difference between freestream at Height and ground level wind velocities. You'll notice on a  x wind approach the  Crab needed to stay on the Centerline "should" reduce (a bit) near the Ground..  Nev

Actually not sure if this definition is quite correct.

Technically windshear is a change in wind velocity over a relatively short distance, it can occur at height or can be in the vertical or horizontal direction.

It's most dangerous when landing or taking off because the plane is already marginal and it results in a net loss of airspeed. Wind shear can provide additional lift depending upon direction.

https://en.wikipedia.org/wiki/Wind_shear

Interestingly enough dynamic soaring uses wind shear to gain energy and there's a lot of energy to gain.

 

 

[Moneybox]

2 hours ago, red750 said:

I had an experience similar to that depicted in the clip. Fortunately I was a bit further out on final to rwy 35 at Moorabbin. This was late 60's/early 70's. Hadn't had my unrestricted PPL very long.

 

I had taken my brother, uncle and brother-in-law on a short local flight, their first flight in a GA aircraft, a Beech Musketeer. We had turned onto final, and were at about 300 ft when the bottom fell out of everything. I remembered what my instructor had impressed on me, and applied full throttle, but held the plane level, overflying the runway level to the ground as I built speed before attempting to climb and slowly retract the flap. Go around and try again. There were a couple of white faces on my passengers.

 

My experience at Jandakot was similar however we were already much closer to landing when it suddenly dropped to what I think was less than 3m. I never had time to react but once we were there I thought we may as well land but my trainer wacked that throttle in as hard and fast as he could even though the crisis was over. All we had to do was cover about 100m of grass and we'd have landed nicely. 

 

I haven't seen the facebook clip, I don't think it's working anymore.

Edited 7 minutes ago by Moneybox

[red750]

6 minutes ago, Moneybox said:

 

I haven't seen the facebook clip, I don't think it's working anymore.

I deleted it and re-posted it.