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Enter Air landing Salzburg

Old 1st Nov 2017, 09:07
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If you look at 1.50-1.55mins, as the a/c goes into a severe right wing down (downwind), you'll notice the left aileron UP accompanied by the flight spoilers. This suggests a large left aileron input, yet the a/c goes into sharp right bank. That would suggest some large right rudder input to remove the drift accompanied by left aileron to counteract the associated roll. Except, either SOD's law was in action and a gust from the left got under the wing, or the rudder input was too agricultural and over-rode the aileron input. We know that at lower speeds the rudder can be more powerful than aileron and needs finesse. Why the a/c then suddenly lunged onto the left wheel is speculation; either the gust was removed or the size 12 on the rudder relaxed and the a/c came under aileron control in rapid fashion.
The GA was an excellent decision and well executed. As in Question of Sport (and it did look sporting) is 'what happened next?' It looked do-able for a 2nd attempt.
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Old 1st Nov 2017, 09:17
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Loose rivets - the NG has poor pod clearance (better than a jumbo though) and will strike a pod at 15° in the landing attitude.

Boeing have obviously tested these conditions and the have decided the margin against podstrike is not enough in those wind conditions. The massively over -developed NG is assuredly not an early jet transport and if one had a pod strike ignoring the FCTM advice a meeting would surely follow even at more enlightened airlines.
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Old 1st Nov 2017, 10:05
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they went back to FRA and did not have another go
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Old 1st Nov 2017, 10:30
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Well, no one came blame the crew for deciding that was enough for today and head back to Frankfurt. Can they?

With so many of these videos on you tube often sensationalised it would be nice if the media occasionally mentioned how well the plane is protected from serious harm by the awesome power , and it is awesome power even on a 737 that can shove the aircraft up and away from danger. In fact as we have seen to some extent the greatest danger sometimes is not being able to control the aircraft as it powers away from the ground. The media cannot seem to get their head around that what really was a risky business in a piston prop or early jet with a horrid spool up lag is a far far less dangerous situation today
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Old 1st Nov 2017, 23:01
  #65 (permalink)  
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JW, yes but 15 degrees would be a dramatic angle, while up to 5 degrees, even 7, might just have saved that right wing dropping - given that it had that extra speed to support the manoeuvre. One would have to be very mindful that a 60 degree crosswind might suddenly become a tail wind and speed an embarrassment. Also, I'm making the assumption that other techniques might obviate such severe compression of the gear, and all that goes with that.

Yes, it's all very different to the old days, though we had to be mindful of flaps. It occurs to me that what happened here could be as a direct result of manufacturer's strangling mandates based on early testing. Days like this one are the real world and demands on the crew might well make dramatic departures from testing envelope limits.

I must make it quite clear, my prime argument is about the strangulation of crew abilities because of hard and fast rules.

I've mentioned recently being thrown sideways over some buildings at about 100' during a Palma takeoff. There was zero on one ASI, and 350kts on the other. I doubt there had ever been the feedback to cover such a bizarre split from current teaching.

Anyway, until there is a definitive log of the ground-speed, any thoughts I have about that issue are little more than guesswork.
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Old 2nd Nov 2017, 04:25
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Gusts take many 3-dimensional forms and, most inconveniently for pilots, don't stay put - plus you can't see them. In fact they could be characterised as 4-dimensional forms.

It's like whitewater canoeing with a blindfold and ear muffs.

You don't know what it is until you are in its teeth. Once you have been nibbled on by one of these beasts, your tolerance of the peanut gallery will be limited.
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Old 3rd Nov 2017, 01:37
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what is the spool up time from approach idle to an appreciable fraction of toga thrust?
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Old 3rd Nov 2017, 04:22
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About 8 seconds max.
Part 25 limits the time from flight idle to go around thrust to 8 seconds
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Old 3rd Nov 2017, 04:48
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I think we're talking "approach idle" here, says the SLF sitting on his couch with Google. I'm trying to understand how many seconds of ground-effect hell the pilots need to endure in such a situation before the TOGA spoolup lifts them away. This is when the decision not to land has already been made. That's the duration when they are basically sitting ducks for crosswind gusts, forced to stay vaguely above the runway and stuck close to the tarmac in altitude.
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Old 3rd Nov 2017, 15:56
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Originally Posted by edmundronald View Post
I That's the duration when they are basically sitting ducks for crosswind gusts, forced to stay vaguely above the runway and stuck close to the tarmac in altitude.
Seriously? You think we are taught to ‘milk it’ until one or both wings stall or engines spool up, whichever occurs first?
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Old 3rd Nov 2017, 16:57
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What a fuss over a normal approach and well executed go around. Not even the cameraman could keep his camera steady. In the 2 minute video, while crosswind in the approach, there seems to be heavy rainfall behind him with the risk of it creating a tailwind in the last phase of final. And look at the trees how they were lashing back and forth. There was a good ceiling and visibility, they flew the crosswind and final approach in turbulent but visual conditions, and perhaps but for the last gust during the flare it would have been a good landing. The GA was a perfect decision, instead of trying to fix a bounced landing. And re the comment of some making it in and others diverting, the conditiions in that sort of weather and can and do vary inmensely from minute to minute. Well done to the crew.
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Old 4th Nov 2017, 00:18
  #72 (permalink)  
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I think we're talking "approach idle" here, says the SLF sitting on his couch with Google. I'm trying to understand how many seconds of ground-effect hell the pilots need to endure in such a situation before the TOGA spoolup lifts them away.
I didn't think that was a bad post from a self-confessed SLF with only couch time logged. I was surprised about the 8 seconds from flight idle, but then, us Denisovans were told the Spey should give us 80% in 8 seconds, while no one really expected it to be from anything but a little less than approach power.

He went on to say:

This is when the decision not to land has already been made. That's the duration when they are basically sitting ducks for crosswind gusts, forced to stay vaguely above the runway and stuck close to the tarmac in altitude.
While I don't think the decision not to land happened then, it does call up many memories involving those crucial moments. Even the guy that did all my line training on the Viscount flew 'my wing' over the VARSIs at LHR. The blades were inches from slicing up some expensive kit.

A reply from FIRESYSOK:

Seriously? You think we are taught to ‘milk it’ until one or both wings stall or engines spool up, whichever occurs first?
I'm not quite sure what that means, but I know the moments on the OP's post were not at all like that. There was no lingering comfortably with retarded engines and then a decision to depart the scene, it was a high stress plethora of conflicts with possibly a tail wind giving one alarming set of imagery and speed, and (if I'm right) a realisation that the ground speed - quickly followed by the airspeed - had suddenly fallen off. From the very best image on a big screen, I don't think there were any major rudder deflections, though that is something that will be recorded.

4djd9
What a fuss over a normal approach and well executed go around.
Well, I've made my views clear over such statements and the camp seems somewhat divided, but I'll tell you what - I wouldn't want to be the owner of that airframe. I'm assuming someone will want to look at the readouts, though if the vertical g is not as great as it looks, perhaps the detective work will end there.

I accept I'm beating an old drum while in a new science. I'd be reasonably confident on that day in an aircraft with conventional controls but telling a computer how to input to the flight surfaces is perhaps something I should bow out from. I'll read in with continued interest.
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Old 4th Nov 2017, 17:54
  #73 (permalink)  
 
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Originally Posted by 4djd9 View Post
What a fuss over a normal approach and well executed go around. Not even the cameraman could keep his camera steady. In the 2 minute video, while crosswind in the approach, there seems to be heavy rainfall behind him with the risk of it creating a tailwind in the last phase of final. And look at the trees how they were lashing back and forth. There was a good ceiling and visibility, they flew the crosswind and final approach in turbulent but visual conditions, and perhaps but for the last gust during the flare it would have been a good landing. The GA was a perfect decision, instead of trying to fix a bounced landing. And re the comment of some making it in and others diverting, the conditiions in that sort of weather and can and do vary inmensely from minute to minute. Well done to the crew.
Absolutely correct. And for you 737 NG guys, wait until you meet the MAX. I jumpseated with a 737 crew the other day and they showed me the differences. One limitation for our company will be an 18 knot max crosswind component for the first 9 months of operation due to a different crosswind technique.

Due to the greater chance of a tip strike due to the scimitar winglets the crab to touchdown technique will be mandated.

Every jet I've flown, from 737 to A320 to 767 I have kicked out the crab starting in the flare and touched down with one wing slightly low, to prevent side gear loading. I've seen the videos of the 380s landing crabbed and the guys I fly with that flew B52s say they land that way all the time.

These guys did a good job with the conditions they were in. They did a great job not trying to save the bounce. Going around and diverting was the best move.
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Old 4th Nov 2017, 20:01
  #74 (permalink)  
 
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I accept I'm beating an old drum while in a new science. I'd be reasonably confident on that day in an aircraft with conventional controls but telling a computer how to input to the flight surfaces is perhaps something I should bow out from. I'll read in with continued interest.
It's a B737 not an Airbus....
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Old 4th Nov 2017, 21:27
  #75 (permalink)  
 
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Thank you for your generosity.


I'm sure the pilots handled a situation well within parameters with a standard procedure that was well executed - I am just trying to understand it. As an SLF armed only with Google and Mark I brain, I'm trying to figure out from basic physics how trained professionals fly me from A to B repeatably and safely.

They come down to close zero altitude above hard pavement at "approach idle" thrust with little energy and DECIDE conditions are not conducive to wheels down. The pilots hit the TOGA thrust buttons, but then have to fly the aircraft attitude themselves, with hands and brains, not computer. The wind is gusting unpredictably.

My naive guess is that in still air they could rotate away 1-2 seconds after TOGA, trade some of their remaining airspeed for a few feet of altitude, and quickly get a kick in the seat from the engine spool up and be away. But here they cannot risk rotating up precisely because as FIRESYSOK says if they slow down, an unpredictable tailwind gust could stall one or both wings while they are just above the tarmac- so they need to keep airspeed, which can now be very different from groundspeed. So they are trapped in crosswind hell, fairly near the ground, for a longer time, something like 4-6 seconds, the thrust lag making it more risky to try to go up than to stay level, even with TOGA already set. After 4 seconds or so, they rotate and the engines take them away.

I'm sure someone with real knowledge will be happy to explain the errors in my understanding. One thing I do understand is that this is a case where the guys sitting in the seats in front of first class are earning their pay.

Last edited by edmundronald; 4th Nov 2017 at 21:38.
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Old 4th Nov 2017, 22:09
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You are missing a lot of information.No one lands at idle in that situation. You don't pull the thrust levers On a normal approach back to idle until you are within 20 feet. When you are making a crosswind landing there is power on until close (really close) proximity to the runway. No 'chop and plop".That is why the flap setting on approach is critical. Flaps out provides drag at landing flap settings, necessitating thrust on the engine to maintain approach speed. On the 757 that would be about 3000#/hr per side (I use EPR on the RB211 - landing weight in Thousands of pounds mover two decimal points over, I.e. 185k pound landing weight would have 1.18 EPR for a ballpark power setting)

You can't go around like they did from a dead idle. They had the engines still spooled and hitting the go around switch resulted in instant power. Someone else pointed out the lack of spoiler deployment. That's because the TLs were up and not at idle.

Don't over analyze this. It was a crappy day and they did their jobs.
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Old 4th Nov 2017, 22:16
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Originally Posted by cactusbusdrvr View Post
You are missing a lot of information.No one lands at idle in that situation. You don't pull the thrust levers On a normal approach back to idle until you are within 20 feet. When you are making a crosswind landing there is power on until close (really close) proximity to the runway. No 'chop and plop".
Huh? He said: "They come down to close zero altitude above hard pavement at "approach idle" thrust"

...which is true, and what you said ("within 20 feet") is consistent with that, so I don't see where the disagreement is.

Incidentally, my airplane specifies idle and Vref at 50 feet, with no deviation for crosswinds or gusts. You're speaking in absolutes that aren't true.
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Old 4th Nov 2017, 22:21
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What airline and what jet do you fly? I've never pulled power at 50' gear above the pavement . And flying Vref in a gusty wind like that is a recipe for a tailstrike on a long jet like an A321 ORD a 757.

There is no way they were at idle on that approach.
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Old 4th Nov 2017, 22:53
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CRJ at an American regional. The particular procedures for your plane/airline can not substantiate your absolute statements that "no one" lands at idle in that situation, or that even on a normal approach you don't pull to idle until 20 feet.

Edmundronald actually has demonstrated a very good grasp of the problem/situation, which is that the spool up lag of a jet creates a vulnerable time gap between setting idle power and touching down, during which you cannot climb and might very well be committed to touching down even after a go-around decision has been made, and power applied. That somebody's procedures for a gusty crosswind would call for a later pull to idle so as to shrink this time gap and mitigate the problem, is a confirmation of his reasoning and not a refutation.

But what I see is not reasoned responses to his posts, but instead people looking to make the most obtuse, willful misinterpretations of them, so as to conjure up justification to jump down his throat for having the temerity to post where only the vaunted professionals are allowed.

Last edited by Vessbot; 4th Nov 2017 at 23:06.
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Old 5th Nov 2017, 20:50
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Originally Posted by Vessbot View Post
CRJ at an American regional. The particular procedures for your plane/airline can not substantiate your absolute statements that "no one" lands at idle in that situation, or that even on a normal approach you don't pull to idle until 20 feet.

Edmundronald actually has demonstrated a very good grasp of the problem/situation, which is that the spool up lag of a jet creates a vulnerable time gap between setting idle power and touching down, during which you cannot climb and might very well be committed to touching down even after a go-around decision has been made, and power applied. That somebody's procedures for a gusty crosswind would call for a later pull to idle so as to shrink this time gap and mitigate the problem, is a confirmation of his reasoning and not a refutation.

But what I see is not reasoned responses to his posts, but instead people looking to make the most obtuse, willful misinterpretations of them, so as to conjure up justification to jump down his throat for having the temerity to post where only the vaunted professionals are allowed.

I don't want to beat this into a dead horse, but.....

When you do a Cat3 approach in the sim what happens when you get a failure inside of 100'? You go around, right? In a large jet, or even a RJ, you will get contact with the runway if the go around is triggered at a low enough altitude. But you are committed to the go, you never, never attempt to land after the go around is initiated. The power comes up from the approach power setting and off you go. I've done a hundred of them, the sim IPs just love to do the "no flare" failure. Or the proverbial "truck on the runway, go around".

I can assure you that if you ever try to abort a go around once you have hit the TOGA switch you will get a bust for that maneuver. The only time you would reject out of a go around is if you totally cocked it up and stayed on the ground long enough to trigger the spoilers or you had selected reveres thrust. The Air/ground switch switches to landed mode after about 3 seconds (sorry, that's off the top of my head). So you have a second or two on the runway to allow for thrust to fully come up if ground contact was made.

I am sure that these guys were spring loaded to do a go around if things did not work out, which is what transpired. When that wing dipped in the gust there were probably two hands ready to push up the levers. You can just tell by how quickly it climbed that the engines were up enough to quickly reach go around thrust.
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