CX Windsheer G/A! post removed
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CX Windsheer G/A! post removed
What's happened to my post about the 118kt bunted recovery from a predicted windshear g/around?
No response from the moderator so I\'ll re-post.
Has anyone heard about the CX 747-400 go-around following a predicted wind-shear warning. They apparently recovered by bunting over at 6000\' and 118kts!
No response from the moderator so I\'ll re-post.
Has anyone heard about the CX 747-400 go-around following a predicted wind-shear warning. They apparently recovered by bunting over at 6000\' and 118kts!
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You seem to know a great deal about this incident already.
What does "bunting over" mean ? (I haven't heard this term before).
What was the Landing Mass and Configuration ? Which airport was it ?
Was it 6000' Pressure Altitude, Density Altitude or AGL ?
Boeing recommended windshear recovery technique permits flying to the stick shaker (which should always be respected). I suspect that 118KIAS is approximately 10 knots above the stall speed at Max Landing weight (in approach config). I also suspect that 118 knots may well be close to Vref for a light B744. Once established safely in the missed approach with positive rate of climb, positive indication that windshear is no longer an influence and terrain conflict no longer a consideration, configuration may be changed.
I suspect that a tired crew at the end of a long sector at a light landing weight may well have taken the overpowered beast to 6000' before levelling off to accelerate and clean up. Most heavy pilots fly Windshear recovery a little unpolished and not as smooth as we may operate in other profiles, usually due to the urgent need to get away from the ground. If "bunting over at 118Kts" means that the aircraft went to 0G for a moment, then that makes the recovery safer still as it would now be 118 knots above the stall speed...(Devils advocacy).
I'm interested to know how you know the windshear was predicted ? If it was a report from a previous aircraft on approach, then it is a PIREP, which is NOT a prediction. If we all threw away every approach where windshear advisories were effective, we'd never get into Manchester or Anchorage in the winter 30% of the time.
What does "bunting over" mean ? (I haven't heard this term before).
What was the Landing Mass and Configuration ? Which airport was it ?
Was it 6000' Pressure Altitude, Density Altitude or AGL ?
Boeing recommended windshear recovery technique permits flying to the stick shaker (which should always be respected). I suspect that 118KIAS is approximately 10 knots above the stall speed at Max Landing weight (in approach config). I also suspect that 118 knots may well be close to Vref for a light B744. Once established safely in the missed approach with positive rate of climb, positive indication that windshear is no longer an influence and terrain conflict no longer a consideration, configuration may be changed.
I suspect that a tired crew at the end of a long sector at a light landing weight may well have taken the overpowered beast to 6000' before levelling off to accelerate and clean up. Most heavy pilots fly Windshear recovery a little unpolished and not as smooth as we may operate in other profiles, usually due to the urgent need to get away from the ground. If "bunting over at 118Kts" means that the aircraft went to 0G for a moment, then that makes the recovery safer still as it would now be 118 knots above the stall speed...(Devils advocacy).
I'm interested to know how you know the windshear was predicted ? If it was a report from a previous aircraft on approach, then it is a PIREP, which is NOT a prediction. If we all threw away every approach where windshear advisories were effective, we'd never get into Manchester or Anchorage in the winter 30% of the time.
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skibeagle,
Just curious to know: are you a pilot? As Basil says one would expect a pilot to be familiar with the term 'bunt', and 6000' generally means 6000 feet above sea level, or 6000 feet QNH or 6000 feet MSL as you may say in the U.S.
I haven't heard 'Pressure Altitude' since I was studying for my PPL so could that be about where you're at my friend?
Just curious to know: are you a pilot? As Basil says one would expect a pilot to be familiar with the term 'bunt', and 6000' generally means 6000 feet above sea level, or 6000 feet QNH or 6000 feet MSL as you may say in the U.S.
I haven't heard 'Pressure Altitude' since I was studying for my PPL so could that be about where you're at my friend?
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Jeez Basil and TDK, what's wrong with a simple answer to a simple question to wit
'What does "bunting over" mean ? (I haven't heard this term before).'
Seems some prefer to be obscure, question another's authenticity, create a scrap, or whatever, than to give a straightforward answer.
Just an internet thing I guess.
I don't know either, I am likewise curious, I am but simple SLF but I have pretty good language skills.
It might be pertinent to mention that while most prooners speak some variety of the language broadly known as English, it is actually quite different in many details for a Yankee, a Pommie, a Brit, or an Indian; and lord help you if you go to, say, Grenada, where upon arrival one of my party asked the Customs people (in her English) what language were they speaking. This did not improve their already poor attitude, as they believed they were speaking English.
'What does "bunting over" mean ? (I haven't heard this term before).'
Seems some prefer to be obscure, question another's authenticity, create a scrap, or whatever, than to give a straightforward answer.
Just an internet thing I guess.
I don't know either, I am likewise curious, I am but simple SLF but I have pretty good language skills.
It might be pertinent to mention that while most prooners speak some variety of the language broadly known as English, it is actually quite different in many details for a Yankee, a Pommie, a Brit, or an Indian; and lord help you if you go to, say, Grenada, where upon arrival one of my party asked the Customs people (in her English) what language were they speaking. This did not improve their already poor attitude, as they believed they were speaking English.
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I stand to be corrected, but I always thought that a "bunt" was a "forwards push on the stick/control column to give a negative G effect ", hence plus or minus G for the a/c type cert.
we aim to please, it keeps the cleaners happy
we aim to please, it keeps the cleaners happy
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Back to topic:
Skibeagle:
My guess is they got a predictive windshear warning from the onboard system, a feature on semi-modern boeings that works in conjunction with the wx-radar and areas of windshear is shown as magenta on the screen..
Skibeagle:
My guess is they got a predictive windshear warning from the onboard system, a feature on semi-modern boeings that works in conjunction with the wx-radar and areas of windshear is shown as magenta on the screen..
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skibeagle etc:
If you push, push, until the crap that normally lives beneath the pedals is on the overhead panel, along with the charts, the Sun, the FOs Racing Post, and the remains of breakfast - congratulations! You have successfully executed a bunt.
Tea, no biccies on the menu. And the CC will piss in your coffee for the next 28 sectors.
R1
If you push, push, until the crap that normally lives beneath the pedals is on the overhead panel, along with the charts, the Sun, the FOs Racing Post, and the remains of breakfast - congratulations! You have successfully executed a bunt.
Tea, no biccies on the menu. And the CC will piss in your coffee for the next 28 sectors.
R1
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Great, I feel really enlightened now. I did find a nautical definition of "bunt": The swollen or baggy part of a sail", nothing about bunt's in aicraft though.
Is it a British thing...???
Is it a British thing...???
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Oxford Dictionary; one amongst a few definitions of bunt: A push with the head or horns, a butt. Chiefly N. Amer. & dialect . Similar to a hammerhead stall, if you are familiar with that.
I understood a bunt was an outside loop, the term used to be used for that quite a bit. Not heard it used as a verb but would expect it to mean pushing forward into at least 1 Neg. G
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From a History of the Royal Air Force:-
"The Messerschmitt's Daimler-Benz DB 601A engine had the advantage of fuel injection which enabled the aircraft to bunt (push negative g at the top of a manoeuvre or climb) without losing power. The Merlin engine of the Spitfire had a float-type carburettor which necessitated the aircraft performing the longer manoeuvre of rolling inverted before diving to maintain positive g, thus preventing the engine from cutting out as a result of fuel starvation"
"The Messerschmitt's Daimler-Benz DB 601A engine had the advantage of fuel injection which enabled the aircraft to bunt (push negative g at the top of a manoeuvre or climb) without losing power. The Merlin engine of the Spitfire had a float-type carburettor which necessitated the aircraft performing the longer manoeuvre of rolling inverted before diving to maintain positive g, thus preventing the engine from cutting out as a result of fuel starvation"
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Let's try to get back to the point.
The matter for discussion is that a CX 747-400 LHR/HKG carried out a windshear Go Around from the approach into HKG.
Somehow, during the G/A, the autpilot disconnected AND nobody noticed. Some of the divergences from the planned profile were noticed but it took a long time for the penny to drop with the 4 man crew that the A/P had disengaged.
The aircraft recovered by pushing over, bunting, shoving the control column forward, whatever [not the point] at more than 6000 feet and about 118kts [the point]
The matter for discussion is that a CX 747-400 LHR/HKG carried out a windshear Go Around from the approach into HKG.
Somehow, during the G/A, the autpilot disconnected AND nobody noticed. Some of the divergences from the planned profile were noticed but it took a long time for the penny to drop with the 4 man crew that the A/P had disengaged.
The aircraft recovered by pushing over, bunting, shoving the control column forward, whatever [not the point] at more than 6000 feet and about 118kts [the point]
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Where did you get your info from? And what do you want to discuss? The MSA out of HK is 5000, so a windshear G/A to 6000 is standard. Admittedly, 118kts, if true, is slow, however I would say that prior to getting that slow, the stickshaker/pusher would have something to say about that. At G/A power, there is a fair bit of grunt coming out the back, so the AOA would have been pretty steep. I also find it hard to believe that no one on that crew heard the A/P disconncect, its pretty loud and hard to miss. CLK is well known for having quite bad windshear, so pilots are aware of it, its often on the ATIS, so the pilots would have been ready for a possible G/A. I am not sure what you are after, but all things considered, it sounds doubtful that ALL the cues could have been missed. Not impossible, but highly unlikely.
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The information came direct from 2 CX pilots at different times and the story is that the crew did not realise that the auto pilot was NOT controlling the aircraft. It's hard to believe [especially witha 4 man crew], which is why I'd like some more information so I don't make the same mistake.The CX corporate safety people and flight ops management are keeping a very tight lid on it at the moment.
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Stirring the pot
It sounds more like you are trying to stir the sh1t to me. You say you want more info so you don't make the same mistake? IF, and its a big IF, this is true, whats to learn as it seems a pretty straight forward mistake, no doubt helped by the end of a long overnight easterly longhaul. Don't let the Autopilot disconnect and not notice, hows that for a lesson.
I think your reasoning for stirring this up is not for your benefit, but as I stated above.
Nosey
I think your reasoning for stirring this up is not for your benefit, but as I stated above.
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NoseGear, if I may...
The MSA in HKG is 4300. Standard missed approach alt from RWY25R (the runway they were attempting to land on) is 3000' initially. If tower was on the ball, you MAY expect a clearance to 4100' (had it once), or 5000', but in light of the attention grabbing display on the PFD, I doubt too much was done in the way of radio calls, or changing of MCP alt until after the 3000' was kicked well into touch.
Where does the
"so a windshear G/A to 6000 is standard"
come from?
I believe the AP disconnect aural warning was over-prioritised <yes I did make that up>by the PREDICTIVE windshear warning they received.
Of greatest concern is the allegation that they ended up on the Tung Chung side of the 25L (LEFT) extended c/l.
The go-around is said to have commenced at approx 1100'.
"Admittedly, 118kts, if true, is slow"
I disagree. Ref-5 is slow.
118kts is terrifying in an AC that should be doing about 30kts more. <Yes, it seems the speed is legit>
The MSA in HKG is 4300. Standard missed approach alt from RWY25R (the runway they were attempting to land on) is 3000' initially. If tower was on the ball, you MAY expect a clearance to 4100' (had it once), or 5000', but in light of the attention grabbing display on the PFD, I doubt too much was done in the way of radio calls, or changing of MCP alt until after the 3000' was kicked well into touch.
Where does the
"so a windshear G/A to 6000 is standard"
come from?
I believe the AP disconnect aural warning was over-prioritised <yes I did make that up>by the PREDICTIVE windshear warning they received.
Of greatest concern is the allegation that they ended up on the Tung Chung side of the 25L (LEFT) extended c/l.
The go-around is said to have commenced at approx 1100'.
"Admittedly, 118kts, if true, is slow"
I disagree. Ref-5 is slow.
118kts is terrifying in an AC that should be doing about 30kts more. <Yes, it seems the speed is legit>
Last edited by john_tullamarine; 27th Sep 2004 at 00:24.
Five Livers, and other Pruners, you appear to over concerned by the low airspeed, which if I recall was also the focus of the original thread.
When an aircraft is manoeuvred harshly nose down (a bunt), it reduces the angle of attack, which if this is less than the stall AOA, the aircraft will not stall irrespective of the airspeed. There are limits to this, particularly attitude, altitude, and the duration of the manoeuvre, but if the nose is lowered (AOA reduced) the airspeed will quickly increase – the same principle as stall recovery.
Similarly, people appear to be over concerned with less than 1 ‘g’, or for the passengers wellbeing in such conditions. It is very difficult to achieve and sustain reduced ‘g’. The force to move a control system usually increases proportionately to the ‘g’ required, this applies to reduced ‘g’. In order to spill the drinks (or the john) then the limit value – normally zero ‘g’, has to be both achieved and sustained, and even then passengers may not be any more concerned than they would in severe turbulence; turbulence at +/- 0.5 g may be much more violent.
The point of this incident is why the crew were not aware of the state of the autopilot.
When an aircraft is manoeuvred harshly nose down (a bunt), it reduces the angle of attack, which if this is less than the stall AOA, the aircraft will not stall irrespective of the airspeed. There are limits to this, particularly attitude, altitude, and the duration of the manoeuvre, but if the nose is lowered (AOA reduced) the airspeed will quickly increase – the same principle as stall recovery.
Similarly, people appear to be over concerned with less than 1 ‘g’, or for the passengers wellbeing in such conditions. It is very difficult to achieve and sustain reduced ‘g’. The force to move a control system usually increases proportionately to the ‘g’ required, this applies to reduced ‘g’. In order to spill the drinks (or the john) then the limit value – normally zero ‘g’, has to be both achieved and sustained, and even then passengers may not be any more concerned than they would in severe turbulence; turbulence at +/- 0.5 g may be much more violent.
The point of this incident is why the crew were not aware of the state of the autopilot.