Windshear

• Show Notes

  Aircraft Windshear. Windshear and microburst phenomenon. Windshear hazard to aircraft, aircraft recovery.

  Accident - Delta 191

• Further Reading and Links

  Accidents

  Delta 191 Accident Report

  Delta 191 Wikipedia

  Links

  Windshear - Skybrary article

• Transcript

  00:00 - Intro

  04:00 - Microbursts

  14:16 - Predictive and Reactive Windshear

  22:13 - Prevention

  28:20 - Delta 191

Transcripts are approximate. Email us if you have any questions.

Intro

00:01

Adam. Sam windshear. Yeah. Lots to talk about on Windshear. Only one word but it's actually quite a few words I've seen both. Well yeah, it's spell check always underlines it in red. When I write it's one word, so maybe it is two words. Have you been writing it to do some research?

00:19

I mean, well, yeah, exactly. Even on the bit I'm looking at now, is underlining red, but then I think maybe it's a dash, maybe it's a wind shear. Interestingly, the perps or I'll talk about the aviation community or the manufacturers they sort of refer to it. Probably encompass that word probably encompasses a lot of phenomena.

00:38

Yeah. They want in the pilots mind. It to just be a trigger and this means this. Yes. So as you could talk about what is wind shear, I don't know how far you want to go down that, but I think in its most basic. Well yeah, let's talk about this most simplest format like because I I'm haven't got very technical mind when we talk about explain it really simply so this wouldn't be technical.

00:59

This would be for their logical point of view, right? So, when I talk about meteorology, it helps me to remember that there atmosphere is actually a fluid. Yeah. Okay. You know, the birds would understand that probably more than us. Yeah. Where's sort of instinctively, I think if it's just like empty space.

01:19

Yeah, of course, that's not really what you want your pilots to be thinking about because there will be no lift if we didn't have, you know, the gas that we're flying through. So within that within that atmosphere, it's the transfer of energy into different states and it can be really powerful.

01:34

Yeah. So if you think about the way it's shear, you know, if you are on a cliff, you'd say is a shear drop. Yeah, that's how you could kind of imagine from that solid cliff shear drop now, imagine the invisible atmosphere. Yeah, well, you've got a sudden change because obviously as you fly through the atmosphere, the wind changes from zero to a hundred knots and there might be a slow gradient towards that.

01:57

But if we're talking about a shear that means a sudden, change like a, your almost exactly high point and all over a low point. Yeah. So that's how it helps me. Imagine what what you're looking at. Yeah, I mean that sounds pretty sensible and I think if you just googled definition of windshear it would basically sounds like you have it.

02:15

Well yeah it would. Especially say the difference in wind speed and/or direction. Over a very short distance. Yeah. So it's essentially what is so then meteorologically the term wind shear means that change in speed or direction over a vertical or horizontal distance and a short one, but what will probably end up talking about in some detail is the manufacturers practical use of the term windshear.

02:42

Yeah. Which if nothing else refers to a manoeuvre that you have to perform. Yeah. And I'm sure we're going to talk about microbursts quite a lot. Yeah. But it could be anything that causes you to perform that manoeuvre. It doesn't have to be a microburst. Yeah, well maybe we should talk about that first.

02:59

And so that is the obvious one which will maybe explain in a little more detail. But other things that I thought of was sort of topographical. So, so terrain being called that mechanical. I don't know which year, I think that. Yeah, yeah. And you also have well, you've got warmer.

03:19

Air descent air or cold, air descending on warm air creates this year. Yeah. And things like inversion layers. You've got a shear because it's kind of that classic like you coming into land and the tower says it's calm less than five knots or something. Yeah. But you look at your wind trend vector and you're only, I don't know if 500 feet and there's like 20 knots of wind.

03:37

Yeah. Oh, hold on. Some is not right here, right? Yes. That's could be no thunderstorms or mountains, anywhere near, but you can have like a nice calm evening, creating a shear. Yeah, so why, why is windshear such a problem to aircraft then? What is? Well, interestingly, you know, I sort of look back at the eighties in the 90s when I wasn't flying, an airliner and think.

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Microbursts

04:00

Oh yeah. They used to crash for all sorts of terrible reasons back then and but hadn't quite occurred to me that and yeah, this windshear problem was something they hadn't got a grasp of yeah, and killed a lot of people. I think in the US between sort of 1960, 1990, you talking about I've got the statistic here.

04:21

But yeah. 26 major accidents 2064 and 85. Sorry. Which is about 650 deaths. That's quite a lot really? Yeah. So they hadn't kind of got a grasp on wind shear slash microbursts. The first one that they directly attributed to was and some wing of a British airline, you know, back in 1956, whatever they record in Kano, Nigeria, sudden reversal of wind direction after takeoff that the pilot couldn't have known about, right?

04:50

So they were aware of it. Yeah. And but it was starting to kill a lot of people and this was at a time, you know, when we were trying to get accident rates reduced, seriously. Yeah. And so I guess we've learnt a lot since thanks to those people that have encountered them.

05:06

Yeah. Well that's the that's the class that we talk a lot in our podcasts about accidents and case studies. And I think what's really important to say is that when we do dissect them and talk about them, aviation has got to be one of the leading industries that looked back on accidents to improve for the future.

05:25

So any windshear accident that we look at and and talk about ultimately the investigation and fear into that, it's probably saved more lives in the future. Sadly, yeah. If if the accident, if it's an accident, which means loss of a whole major damage or loss of life, I think versus an incident.

05:42

Yeah, then unfortunately, something bad has happened, but we'll learn a lot from obviously. The idea is that we learn proactively by occurrences. I we nearly had this happen and so we learnt from it, but there's obviously a lot of accidents that have led up to and learning about how pilots and stand the windshear phenomena.

06:03

And I kind of got the feeling reading, all the accidents and transcripts. You're interesting to think. Yeah, well I would never put myself in that position but you kind of think they were in the wrong place at the wrong time and would I have done anything different? Because let's talk about a microburst.

06:20

I think it only lasts a couple of minutes. Yeah yeah. I mean you're pretty unlucky if you're that aircraft. Yeah. That moment on that airfield because regardless of fact that there was microburst conditions present which you wouldn't have perhaps understood 30 years ago but you might now you're still pretty unlucky.

06:37

If at the moment you are making your approach or takeoff that it decides to dump and sort of on top of you and also the sort of going into microburst now but the diameter of them. So it's less than four kilometres. Yeah is a microburst. Yeah well that's like your average runway length.

06:56

So yeah, that's interesting. So you know if it's just slightly over to one side it might not quite have the same effect. Yeah. See pretty unlucky and I guess that's why there are slow, is that right way to to get handle on it because they're kind of insidious and they're like, almost invisible.

07:14

Yeah. And these thunderstorms is people probably know about their formation of a thunderstorm, is it? It forms and disappears as quickly. Yeah, you can't put it in a jar and study it. Yeah. That that particular thunderstorm that cause that crash is gone and we can't see any car. Yeah yeah exactly.

07:29

So yeah so let's talk about the microburst ends. So essentially as a thunderstorm builds it's rocks energy up from from the ground basically to give it. Yeah. And as it grows and then eventually that air is cooled by moisture in the cloud and then it begins to fall in a kind of downdraft.

07:50

Yeah, I mean, thunderstorms are the example of what we were talking about which is the transfer of energy in the atmosphere and a really great example of mother nature, if you like right in front of your eyes. So yeah, you've got the energy latent energy. That's if you've got an unstable atmosphere, so air is rising meteorology.

08:10

There's so many factors and just you just one of them. Yeah. And then you get this big effect. Yeah, say a factory that is pumping out, heat might cause convection and if the environmental lapse rate is unstable, then all of a sudden, you get this runaway effect where you start to build a cloud, then a cumulonimbus or cumulus and cumulonimbus and then into a thunderstorm and with enough energy in certain parts of world, you can get these supercell thunderstorms, and it's the air that is cooling then condensing.

08:43

But then because the change of state into water, you then get more energy released, and it's sort of feeds itself. Yeah. And you've got different temperatures and then you've got draughts and you go updrafts and downdrafts and then you've got this machine and sky called a thunderstorm. Yeah. Yeah.

09:00

That's a really good way of explaining it. And so to say, keep it really simple. So these downdrafts, they kind of, I kind of best way I tried to describe it in. Simple terms, it's like anyone's got a Karcher or a hose, a powerful hose pipe. You just fire it at the ground.

09:16

Yeah. You know, when the water hits the ground? It just sprays off in all different directions, so say, yeah. Yeah. And so, for an aircraft coming towards that, so flying it, we've obviously fly airspeed. So initially, if you imagine you see the Google picture of a microburst you, yeah, you see it you initially gonna start with a headwind because it's spraying out from from the sides.

09:41

And if you go ahead when that's gonna increase your air speed, so the aircraft's gonna need less power to maintain your target speed, so you into a headwind, but then almost immediately that headwind drops off as you pass through the centre of it and come out the other side and you immediately turn to a tail winds.

09:57

So now your speed starts to wash off dramatically. Plus you've reduced your power essentially to cope with the headwind, right? Yes. So the aircraft's in a really low energy state plus the actual downward motion pressure from the downdraft is essentially creating this massive loss of energy in the aircraft and pushing it towards the ground.

10:17

Yes. And and now different numbers quoted but could be up to 6,000 feet. A minute down draft? Yeah, yeah, I mean flying through it. A CB is pretty turbulent and I think smaller aircraft would actually have structural failure. Yeah. Yeah. Because the draughts inside the cloud and then imagine these draughts suddenly come out of the bottom of the cloud.

10:37

Yeah. And then what you've just described is like the classic diagram of a microburst which is like you say this upside down, mushroom card, that is finding out. Yeah, it goes down hits the floor and then goes threads out, you get these horizontal winds then. Yep. And the classic aircraft that flies from one side of that diagram to the other and how it's like horrible trap.

10:59

So I mean most people will have experienced like oh there's a rain shower sort of coming towards you. You know, if you just a pedestrian or whatever walking around, you feel a draught. Yeah. Yeah. Associated with the rain is about to start or with the rain. It's exactly the same thing.

11:13

Yeah. And microburst can be wet or dry. Yeah. And that unfortunately means that we may or may not have an idea that they're there because of the systems will that we're used to pick them up. But the ones with a lower cloud-basing tend to be wet, but if they have a higher cloud base their brain often evaporates for you.

11:34

So, guess the ground. So yeah. Four kilometres in diameter. That diagram, you've just kind of disappeared from one side to the other. And yeah, imagine you're flying into an airfield and that happens to be over your effort at the moment you're making your approach. Yeah. Yeah, exactly. Yeah. And they say, we the speed that we travel, there's only 30 seconds to a minute.

11:55

Maybe. Yeah, that's kind of where that out if you're, you know, a thousand foot, if it's all happens really quick. Yeah, basically, yeah, exactly. And you can hit the ground in no time and that's it. And that's the going back to the blunt. Definition of windshear is a large change in speed of direction.

12:11

Over a very short distance. Yes. Essentially the markets like the west not. Well yeah the worst because the most common is low level windshear low level. Yeah exactly. In high altitude flight, if you go across a jet stream, you could you'll probably definitely have wind shear. Yeah. And and you might have lost controls all sorts of hazard associated with that, but at least you are not 500 feet around ground.

12:36

Exactly the low energy state at the time. Yeah. That's the big threat. Isn't it funny that you get those hurricane hunter aircraft to fly into hurricanes? Right? So how can they do that? But airliners can't make it under a thunderstorm. So looking into it. And that's a good example because this horizontal windshear in a hurricane and it's quite uniform as well.

12:58

And predictably, okay. That's kind of like an extreme version of those flying across a jet stream. Sometimes you won't get any turbulence. Yeah. And it's all horizontal shear, even though it could be a sharp shear. Yeah, but what we're talking about here is a big vertical component as well.

13:12

Yeah, funny as well, that I associate with aviation but obviously it's a hazard for anybody. So a lot of ships have capsized because of microburst. Yeah. So just as and has it for those guys especially sailing vessels with an actual sale. Fireman can be putting out fire forest fire and microburst.

13:32

Yeah, and I found a video of a toddler on a tricycle on like a Russian dash cam, right? And then he gets hit by a microburst really? And he's tried schools going backwards. Oh no, right. Okay, yeah, yeah. I mean I've never seen one no. I tried to see if they were present in the UK and there's this paper about one that may have happened in Farnborough in 1984 but that's how obscure they are you in the UK.

13:58

But of course, our job is to fly to other places. Yeah, well there can be large thunderstorms talking about as flying can you if you ever had a window? I don't think I've ever had even the reactive wind shear a warning. Go off pop from in the simulator, a lot of times.

14:16

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Predictive and Reactive Windshear 

Yeah so we practise it simulator, I've never had the reactive windshear from what we'll come to explain, maybe what if it's been reactive and predictive. I've had a predictive wind shear the holding point of the runway before. So the difference the reactive in the predictive or exactly as they say really are on most modern commercial aircraft, the predictive, it tends to be a function of like the weather radar, so it's pretty projects ahead.

14:40

It predicts based on the sort of moisture ahead of the aircraft and has a look and basically assesses where it predicts, there might be. Yeah. Some some windshear I found out it uses the doppler effect. Yeah. Like a traffic cop trying to do for speeding. Yeah, exactly. So they measure the change in frequency.

14:58

Yep. When they, I mean the in layers turns, they bounce microwave signal offer. Yeah. As it comes back, the change of frequency. Will give you an idea of that particles velocity and I think it's looking for horizontal velocity. I might be wrong about that, but that's all I've ever had is the holding point of predictive wiring.

15:16

We had a look on the path and it was kind of quite close to where we were supposed to be flying so we just held off for a little while. I reckon I've had scenarios where I think probably it should have the reactive so go back to the reactive will be right?

15:29

Well, what is the reactive that is an actual? Yeah, that's the aircraft fly control. Computers actually taking all the data and info from externally. And I think clearly it's a comparison of the inertial data with the aerodynamic data. That's all it does. Yeah. So what the aircraft should be doing?

15:46

This is first is what actually achieved today is achieving. Yeah. And it will trigger windshear when you want it. Yeah, so I've never had an actual reactive warning but I think I have I recommend conditions where it probably should have gone out but not because of a microburst, no, no because microburst know what because it's gusty?

16:03

Well. Yeah. Because because of the strong change where particularly thinking about sort of airports, like Gibraltar or that's okay, or Tenerife, you talk about microburst being the classic. Yeah. But these obviously, like sort of graphical? Yeah. Reasons. So you imagine. So for those, you don't know, sort of say Tenerife if you're looking at Tenerife from like a drone above the island, it's a massive volcano basically.

16:28

And the airport is right on the south of the island and it's at East West facing runway. So if you've got, like a northerly winds, that's coming down, hit on mountain and just like water, the air will just take the path of least resistance. So yeah, it'll kind of swirl around the base of the volcano and a bit over the top as well.

16:50

Potentially. Yeah. So you could be coming down final approach for let's say the easily runways there are nine, so you're facing an easterly direction and all of a sudden, you get a sort of tailwind from there. The wind coming around the base of the mountain, but as you kind of get to the wrong way, you start getting a bit wind, that's coming the other way around the mountain, that which becomes a quick, a certain headwind.

17:13

Yeah. Plus the wind that's coming over the top and down the east side of the volcano as well. I didn't a bit of sort of crosswind element as well. So you got changing direction change direction and possibly speed. And yeah, so that's it. That's kind of wind shear. But not and you're saying market but in your experience, the reactive when she hasn't gone off.

17:33

Yeah, yeah. So when I felt, you know, as when you sort of certain the city, you feel that loss of energy. Yeah. Because I don't know what the they don't really tell you what the threshold for the system is, no, but it kind of good. They doesn't go off I guess because yeah, yeah, I guess so is the aircraft in danger at that.

17:48

But then what about PIREP learn about windshear at Tenerife? I think, you know, a pilot report while it report on the, a s, it might say. Yeah. Like negative. windshear. Positive windshear. Yeah, so what does that mean? So that's in terms of whether you're, you know, air speed is gonna increase.

18:09

Like, so you're gonna get a positive shear or whether you're gonna lose energy negative windshear and they usually give it a knots as well as to roughly how many knots. Yeah, you can expect, if you get a negative wind shear, you lose headwind, you have it, you gain a tailwind, which the aircraft air speed indicator sees, as a loss of airspeed.

18:28

Yeah. So your ground speed would be the same, right? So airbus would argue, well, we already deal with that because you have you fly consistent ground speed because you've told us what the ground wind conditions. Are you input that from the tower eighties? You put that in the FMS?

18:44

Yeah, I'm based on that. It knows that's where it's ending up, anyways. What the inertial wind data is at that time and so it tries to fly a constant ground speed all the way down Tenerife Gibraltar. Yeah. Like who built an airport there basically. Yeah, we end up thinking to a massive rock or mountain.

19:02

Like we were saying about fluid. If if you have a stream that's running down picture a river and then you put a rock in the middle of the river. You will see the water tries to obviously flow around the rock in there. On the other side of the rock you've got little whirlpools exactly swirls.

19:17

Yeah, that's exactly what's happening or here where I live on the case or anywhere really. You get these big coastal winds and then as you walk between the buildings yeah, you suddenly have this incredible like 60 knot wind. Yeah. Yeah. And your hair goes everywhere. Yeah. And as soon as you're out of the gap between the buildings and you're actually on the front, it's less wind.

19:37

So you've gone through a shear. Yeah. Created because of the venturi sort of effect of the yeah, the building. Yeah. Yeah. So reactive when shear systems almost are like the more primitive but actually they do something different to the predictive but they came first. Yes, I think NASA helped design predictive winter systems and they tried a bunch of stuff were like using infrared systems.

20:03

That look at aerosol particles which are really tiny and but the the system we use is the weather radar which we use for all sorts of things. But the weather radar is also has this function of being able to use the Doppler effect. But like I was saying earlier, if the microburst isn't wet, it might not be able to see the wind because the particles until you small.

20:24

But the reactive wind shear is just like got its eyes closed. It's not looking ahead of the area. It's nothing like that at all. It's just comparing the air data to the inertial data. And it thinks hold on, why am I being pushed down into the ground when I've got a normal power setting.

20:40

Yeah. And airspeed. And so on. And so then it shouts windshear. windshear, and we fly an escape manoeuvre. Yeah. But getting back to what you were saying earlier about. You had one at 10, a reef. Yeah. Or were you saying them you've had predictive so? How to here about they're holding point before, takeoff.

20:57

So prevention is better than cure. Yeah, or we talk about thinking ahead and in my mind that's you can't go to heavy on that message which is you don't have to make that approach that take off. And this is possibly a message that wasn't sort of around back in the sort of 60s and 70s, you know, I think there's, well, I think there's three three sub areas as to why accidents related to windshear happened, a lot less now a because systems are better at detecting shear and with the knack, what NASA helped to build weather forecasting and assessing of caring.

21:32

What you're saying I was gonna ask you about how helpful you think traffic controller. Well, yeah, okay. We could talk about that and as well. But then also pilot procedures and I suppose, you could put it under crew, resource management, and SOP start rate procedures, you know, ways of actual procedures for dealing with windshear that maybe weren't there in.

21:55

Yeah, it asked. And and that, that's sort of helping to reduce massively the number of accidents. So yeah. So sorry. So you asked me about prevention better than the cure. So yeah, so airlines will have sort of procedures in place. Now, for example, in my example a predictive windshear before I took off.

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Prevention

22:13

Well yeah, the obvious answer, there would be to delay the takeoff but anytime you can run out of fuel you may. Yeah. Impacts on the commercials. Yeah, they're willing they're like oh okay. Yeah you're blocking you know, the alpha holding point. Yeah. Yeah. Something like that. So it's, you know, ultimately safety first, but there is obviously the commercial side of it comes into eventually, so maybe you're in the situation where it's actually safe to take off and maybe the water the windshear you've held off long enough that the windshear windshear alert has gone but they're still obviously wind shear around so, but at the aircraft is using its doppler effect in its same monitor radar display or windshear head, something like this.

22:56

Yeah. And what, what sort of information could you be gathering? I mean, I guess you've got the meta. Yeah, local sort of weather pilot report. Yeah, traffic control, maybe information. So there are some turnarounds where I've gone and stood on the steps and just took it in. Yeah, there's 360 panorama maybe of the airfield.

23:18

Yeah, you can. So you can understand what's that over there. Like directions, the worst weather in which way is best. You know? What is our departure? Taking us in that direction. Yeah. Yeah I agree. I agree. It's funny that and if you are the first one to say, I'm not going.

23:34

You might start chain reaction of. Yeah, we're not going actually, but it's easy. I think to say, well no prevention is better than cure. You know, shouldn't have made that approach in the first place but that's our job. Yeah, you said safety first, but you know, that there's a risk.

23:51

Yeah. That the wind shear will cause a loss of the aircraft and loss of life, but what's the likelihood of that occur in? Yeah. Okay. So what are we doing to mitigate that risk? We've got prevention, we've got windshear manoeuvre to escape. So, you know, we have to make approaches in weather in challenging.

24:11

Yeah, definitely. But we have also have to one day. Say not, not this time, not today. Yeah. What's a good piece of knowledge for me? I think would be to get an idea of how long that thunderstorms gonna sit there. Yeah. Because I've got a certain amount of fuel.

24:25

Yeah, so the whole point are in the air in the hold kind of have this feeling. Well, I've got to get on the ground somewhere, but I wonder how long I could hold, because even these microburst they only last couple of minutes you're not going to know if there is or isn't a market but of quickly a thunderstorm is going to move away from the airfield and that'd be good.

24:45

Good knowledge to have when you sort of planning. Yeah, I guess your fuel and your management. There is also things you can do to put yourself in a slightly better position. You can fly a faster speed if you're landing or take off. Performance permits it. Yeah. In land with different flap settings.

25:01

Yeah. So I think we're encouraged to take a stage of flat less on an Airbus flap three. That's for an escape manoeuvre. That will give you a better chance. Yeah. But if it's gusty conditions, you actually have better manoeuvrability with the standard flaps and so there's still nuances there and you can add airspeeds to approach speed.

25:20

Yeah. What else can we do? Brief rehearse, the manoeuvre. Yeah, very powerful tool to just rehearse the manoeuvre. So the first time you're doing it, it's not the first time you've what about monitoring is rolling the manoeuvre because I was gonna ask you what you thought about this because I just generally, if I'm PM read out a load of stuff.

25:38

Yeah, helpful. But I come to learn looking at some of this stuff that As speed might not really be a factor during the manoeuvre, so your angle of attack and your proximity to the ground. Kind of like the important things. Yeah, if you are saying the airspeed, I wonder if you'd actually almost tempted in the pilot flying to do something, they shouldn't do, because regardless, what the airspeed is doing, they shouldn't be reacting to that from my point of view, as any of this is, you know, as a trainer but as PM I wouldn't be so focused.

26:13

I try to think you know, and I'm in the simulator if I'm doing a windshear manoeuvre, I'm not really listening that much to what PMs, tell me, you know. Yeah. Speeds increasing speed. That means nothing to me. I'm just I'm doing the manoeuvre. Yeah. So as PM, what I try and do is I actually try and do the manoeuvre as well.

26:28

So yeah, that's more my focus on the meaning. That's obviously their first job of monitors to see that they're doing them an even correctly incorrectly, but yeah, in terms of actual information after that, just trying to be useful to try and say, but I just wonder if this is nuance.

26:42

I didn't pick up on that like telling the PF, how low you are to the ground is number one? Yes, you'd actually isn't relevant. It's probably less reverent. I do think simple. Terms, like climbing descending, like we're descending. Yeah, sending. That's probably the thing I learnt, I think I got this right there in the downdraft, the pressure can suddenly change.

27:01

And that will tell the VSI that you may be climbing or descending when you're not. Actually I really radalt is like the number one thing, because that's true. Yeah, that's interesting. Yeah, not talk about that. But yeah, I mean, when you're in a high workload situation, like a memory item.

27:17

Yeah. Potentially communications, the first thing, your brain shuts off. You might not be able to hear the PM anyway. Yeah, kind of easy for us to fly the manoeuvre now compared to before these systems, because we just have to follow the flight director, that's it. Yeah, yeah. Flight director is going to help us keep a high potential energy and then if hitting the ground becomes the threat, the flight director should just keep pitching the aircraft up until you're at the maximum angle of attack.

27:42

Yep, so that's quite straightforward. So that's so this is, if this is a change probably from back in the sort of 60s is that although there were maybe pilots had an idea of how to recover from a windshear there. Maybe wasn't sat down parameters for establishing when you're in it and possibly not specific procedures.

28:00

No, for getting out of it, you know some airlines call. It toga. windshear windshear. Yeah, the actual recovery manoeuvre. So on our currently, there's not many memory items like compared to what you'd think. But windshear is an absolute memory item. Yeah. So I think that's helped obviously over the years is having some sort of standard procedure to yeah.

28:20
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Delta 191

Escape manoeuvre basically. So let's talk about what they might have done before. They had an escapement over by looking at Delta 191. So Delta was Delta 191 back in 1985 so it was a flight from one coast to the other. I think across the states, but it had a stop off at Dallas Fort Worth which is where the accident occurred aircraft.

28:46

Not that it's really relevant. Was a Lockheed Tristar. Yeah. So how many I think there's three crew? Three crew yellows fighting. There was a flight engineer. Yeah. Yeah. Absolutely. From Fort Lauderdale on this leg. That's it to LA. Maybe I think it's going to LA but stop in it, but stop it.

29:02

Dallas. Yeah. Okay from why red there was sort of weather, Paul went half forecast in Dallas Fort Worth, the crew were aware of it pre-departure but also updating the weather on their way to Dallas. Okay? And as they got bit closer they had received reports of not windshear but rain showers, thunderstorms etc.

29:26

So this is continental North America you know we're talking potential for big thunderstorms even tornadoes in some parts of the country. Yeah today used to these things popping up. Yeah. And they I think they did some goods creatures some good avoiding in the early stages. So I I think the wrong ways they were landing on in Dallas was generally sort of north south orientation, their arrival initially, coming from the east.

29:51

But I think their original sort of star standard arrival. Procedure took them through some weather. So they actually asked for a different arrival, which brought them more northerly. And I have to say, I'm not sure about then, but now this states was quite different to Europe. Is the ATC have weather radar.

30:09

Yeah. And they do not expect you to ask for avoiding vectors. They give you them in advance as they get offended if you have. Yeah. Yeah. So, you know, they, they try to avoid by coming on a different arrival. There were preceding aircraft on that arrival, who reported? I think one reported line for a rain shower.

30:30

Yeah, one reported sort of light to moderate turbulence, but not more, was it? It was a leader. It was a sort of fairly light. Yeah. So there was nothing really to lead them into thinking. This was gonna be really, really bad. Yeah, and I've learnt that the two aircraft that were behind were interviewed and they their words were something online of all crews on those aircraft behind had no reason to do anything.

30:54

Other than continue, the approach, they were going to do exactly the same thing and they're very surprised when the aircraft in front crashed. Yeah, exactly. So yes, it wasn't. That would be interesting very reckless or anything like that. You know, say information they had there was an aircraft about to take off as soon as this aircraft would have passed in front of them.

31:14

And this aircraft take off path, would have been sort of more directly towards the thunderstorm and they were ready to stand up the throttles. Then they reported just after this aircraft crashed that their aircraft was rocking on its legs and their ASI. Even though their stationary on the taxiway, was reading 70 knots.

31:31

Wow. But they, he was about to take off about. So yeah, with no concerns, the they essentially they lost energy and crashed about they, like the classic they went to horrible way to sort of like summarise it, but they went through from one side to the other of the diagram.

31:48

It's such a short distant. Yeah. If you watch the computer and generated diagram of where they are on the glide path to CVR overlayed. Yeah, it's so quick so quick and what struck me? I can't remember the exact numbers but was the rate of descent. Okay was about a car I can't remember how many 3000 fpm.

32:08

Yeah, guys, it's converted from me to these are in meters. Maybe it's 3,000 feet per minute at one point and maybe up. It was, it was quite a normal rate descent on an ILS or 700 feet per minute. Yeah, so yeah, essentially for four times and if we got anywhere near thousands, we'd have to make calls as part of monitoring and basically go around pretty much after that.

32:28

Yeah. But if it's uncommanded, that would be extremely unusual. Yeah. So yeah, essentially so they got pushed into the ground basically. But actually I read that the aircraft landed in a ploughed field. Just just about two kilometres short of the runway. It was actually largely intact when it landed and it sort of skided along this ploughed field with everybody still alive, really initially it was only as it was sort of reducing speed actually got the highway and clipped.

32:59

Yes, like lamp posts. Then it started to break apart and something the water tower, then a big water tank. Yeah. And caught fire. And I think it was really the fire that killed, right? Most of the people almost everybody died. There was a few survivors he survivors at the back of the yeah the tail plane.

33:18

So it broke away and right, made larger intact and that's where most of somebody, I think died in a car here because, yeah, hit the highway. Yes, I bet. Yeah, they touched down before that bounce and then killed somebody in a car across the highway and then these water tanks.

33:31

I think they unleashed a lot of water, which made it difficult for the fire and rescue to the ground was waterlogged. Right. Okay. Okay, a swamp. Yes, yes, exactly. Yeah. Well I didn't know I didn't read that a weird sort of snoring like a river. If you're a. Yeah and all the crew died, they're CVR is available.

33:51

And you can hear the communication between the two. They're wonder because they not doing anything wrong at all, but the PM that was a captain, the pilot. Not flying was obviously telling the first officer about their airspeed. Yeah, so they're reacting to that. Actually interesting thing about Boeing aircraft versus our Airbus is if if in an airbus, you go to, you know, what you'd call firewall the throttle, levers, the threshold is sorry, say, you go, you take, that actually is a switch as well triggers a switch, which means that we're now in a mode where it's just going to provide, toga thrust whatever happens and on their aircraft not boeing but with a more traditional auto throttle, although they physically push the thrust forwards.

34:38

When the airspeed went really high, the aircraft tried to help them by reducing the throttle, right? Okay. Okay. So kind of something that we don't have to worry about on an air by aircraft or if you do the procedure right on any aircraft but that you want to be building up as much energy as you can as you travel through this.

34:56

Microburst. So even if the ASI goes high you then got a later potential energy in the aircraft which you could trade for altitude. Yeah. So at. No. And would you want less than four power? Yes. Even if your ASI certainly jumps some USB centily jumps high. Yeah, yeah. So that's unfortunate.

35:11

So yeah. So these sort of NTSB concluded as they always do. With accidents, is never. Just one soul reason. It's this, this Swiss cheese, we talked about, and if you removed any one of these items, it probably wouldn't have happened switch cheap. I have Swiss cheese. I mean lots of holes in slices Swiss cheese, and if you put all the slices together and the holes, like holes, all line up that does that's when you have a nice cheese without any holes and then holes in and can't pack that would prevent the accident passing through.

35:44

That's the kind of analogy the NTSB concluded and there's three main contributing factors and the first one that they should be to pilot error for flying through a thunderstorm. Right. So that time pilot arrow obviously made me mad. Yeah, it makes me mad as well because then that's, that was used.

36:02

But now we would unpack that. Yeah, to the end of the earth. Yeah. You find out what we mean by that pilot error? The second reason was an extreme weather phenomenon, what they describe is a microburst induced wind shear which is what we've what we've talked about and then the final contribute to factors they say was a lack of specific training policies or procedures for detailed.

36:22

So remove any one of those three. Yeah. And the accident probably doesn't happen. Which is typical for air air aircraft accidents. Yeah, of course you know if there wasn't the microburst then it probably wouldn't have happened and half as a minute later. Could have been a different. Yeah. Yeah.

36:38

Might have just made the difference between hitting the ground and not. Yeah. Quite a few of them in those statistics in that time period. Where they've lost 650 lives in those more, that would be like 30 years or something. There's a lot as well that got away by the skin of their teeth.

36:54

They you know, got really low managed to risk to escape it. Yeah. So there's plenty that we're nearly accidents. Yeah. Okay, say I guess they were getting fed up by 1985 then. Yeah. So this was a significant accident and the reason that we kind of picked this one is because this was, when they're kind of FAA, right, America decided, right, we need to do something about these accidents.

37:15

And so you alluded to earlier, NASA actually at Langley. They used an old Boeing 727, I think it was to sort of trial and test. This doppler-based weather, radar and creates some sort of wind shear alerting. Yeah, our system. And this was quite quickly successful and inserted on to.

37:34

So that would be PWS. That would be predictive windshear. Yeah, so I'm unsure the timeline but they also would have introduced the reactivity before the partitions I think. Yeah. It's now mandated that all aircraft have to have predictive. That's right. Yeah, absolutely same. Yes. So that was mandated by the FAA.

37:51

Do you know of any say even more up-to-date aircraft if they have any more advances in? And what I'm imagining is that their information from the ground. So their data uplink, all yeah. Is a feature, even in light aircraft and so position of cells with data things like this, you're going from a from aircraft-based systems to ground-based systems so you can gather more data, more data.

38:15

I don't know about specific, wind shear warnings, but certainly things like lightning, strikes and can all be overlaid on a map inside the aircraft. Yeah, radar and things like that. So, I wonder if that helps pilots build up a picture while I'm on that. Actually, I wonder and how how often do you scan?

38:32

The wind trend arrow and wind data. Their inertial wind data in the aircraft because it's on our end, you know our PFD. Yeah. And I don't really know that after, but I reckon I was thinking if there's a hints of wind shear or unusual wind activity, I might I'm looking at I am and I think I need to actually cognitively kind of look at it in a different way than normal.

38:56

Because that from what I understand is going to give you much earlier. Clue. Yes. Send your airspeed and actually date. There's a problem. Yeah, definitely. Because of course, we can do a windshear escape manoeuvre even if the system doesn't go off, we can just say look this is when she is switching, it's going to perform the manoeuvre.

39:12

Yeah so we have a set of parameters listed in one of our operations manuals which says if if any of these parameters are exceeded and it's that is a sort of self-diagnosed windshear. It's such in such an attitude change or whatever. I can't memorise that. I say I sort of just think if it doesn't look right.

39:29

Yeah yeah, that's the way I train it. I've got a sort of for our airlines numbers and yes they use. Okay. I saw easy way to try and teach people to remember it but yeah, absolutely. Ultimately in the heater battle if it doesn't such a pilot fray every day.

39:45

If it doesn't look right. It looks really wrong. Yeah. And then yeah absolutely. It's it's becoming unsafe and therefore you need to carry out that windshear recovery escape manoeuvre. So I wonder if we're gonna have a have one in our, in our careers. Yeah, I'm sure one day we will like say I've seen a lot of them in the simulator.

40:06

In fact, it's one of the current topics. We're teaching in the simulator. Yeah. When she recovers, most cruise really good at dealing with it, but they obviously know it's coming. It's likely to be that day that it'll come where. I mean, I've diverted because of it, but I haven't actually gone into it.

40:21

And at a point where the airfield had so many, and if that, I'd say the most common windshear that I come across, is because of buildings. Yeah, so low level around an airfield, you got these big hangers. Yes, certain specific directions of the wind are really nasty, create really nasty environments at one of the threshold, maybe a hundred feet.

40:43

And if every aircraft is getting a windshear and going around, I think what happened to the effort I was approaching was there. I will wish shut then. Yeah, because it the airfield is the hazard. Yes, everyone had to divert, okay. But it was there was no wind shear until you're on the lease side of that hanger just here, that's a strong stormy day but not necessarily wind shear from any kind of phenomena, until unfortunately, someone's built a hanger in the way.

41:11

So quite a serious topic but aircraft still crash because of wind shear. Yeah, so if not, we've not got rid of the problem, you know, I've got all these systems we've got this system. I was looking into that, they just didn't follow there, the windshear. Manoeuvres say, yeah, even though they had the alerts going off.

41:30

Yeah, cool. Well, if you want to learn more about windshear, that's a good accident. Yeah, to look at Delta 191, that's one. Where else did you say? Yeah, I mean, obviously the sort of your, the ATPL studies will have more of the theory behind what wind shear is, but I always find.

41:48

Yeah, just just looking at windshear related accidents. So I always talked about good for what wind. She means to us as pilots. Yeah, of course. This upper altitude stuff and we could do a whole hour on a clear attabellence flying through jet streams, upsets aircraft upsets altitude, but that's why that down for a future.

42:08

Alright, well, if you episode say next time, then? Yes.

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