Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

AF 447 Thread No. 7

Tech Log The very best in practical technical discussion on the web

AF 447 Thread No. 7

Old 1st Apr 2012, 16:03
  #1181 (permalink)  
 
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes on 0 Posts
POV only.

From an historical perspective Airlines safety has everything to do with two things.

Dramatic improvements in Powerplants, and a better understanding, and management of Weather.

Both had to do with economics. UAL: (on the DC6) "RADAR equipped".

Time in Transit. Less fuel with a concomitant increase in pricing. Safety is in there, but mostly as a left handed marketing tool. It is poor marketing to allow clients to think too long of safety.

The result of the sacrifice of these folks will be in catching AirFrance with trousers down. For money. Is there another way to see it? To the extent that punishment is harsh, and the deal improves for passengers/crew, it is a sad but important take-away.
Lyman is offline  
Old 1st Apr 2012, 16:23
  #1182 (permalink)  
PJ2
 
Join Date: Mar 2003
Location: BC
Age: 76
Posts: 2,485
Received 1 Like on 1 Post
Machinbird;

In re the sim exercise, power was at various settings (though never TOGA). Also, there were variations in altitude needed for recovery. In one exercise we "did nothing" and the aircraft happily remained in stable flight at FL350 as power remained in "TOGA LOCK" (last setting before disconnect) and the pitch at 2.5deg, approximately.

I suspect some tests of hand-flying the A330 in Alternate Law would be part of the investigation to see how sensitive the aircraft is, to further understand the initial actions on the stick of the PF.

As I've mentioned a number of times throughout these threads and because not all here seem to comprehend, the air is much thinner at cruise altitudes and so with something the mass of an airliner one must be gentle with the controls and make tiny stick adjustments in manual flight. This fact was first stated in Davies' book, "Handling the Big Jets", in 1967 - 1970.

gums, you're right about the sim not really being able to teach this kind of thing - you can't feel "the mush"...the slight delay in responsiveness in both changes in attitude and flight path even though the subtle indications may be accurately simulated. These kinds of things need to be taught in the airplane at cruise altitude. The airplane hand-flies very well in cruise in Normal Law but I haven't flown it in Alternate Law so can't comment on that. Alt Law is supposed to be wysiwyg. I've hand-flown other transports at cruise which don't have C* Laws or the "add-on's" which provide the usual protections we see in these aircraft, (the B777 has some protections built in and I suspect the B787 has more), and they're sensitive so it is important to know how the A332 responds when hand-flown at altitude in Alternate Law. I suspect with gentle handling it responds as any other similar type, (but "gentle handling" it appears, is not always natural and must be taught)

I stress too, that, in accordance with most air regulations (I have cited the CARS here in the past but the JARS I suspect are similar), the simulator is only used to teach the approach to the stall and not stall recovery. The full stall is never taught and is not required to be taught, for a number of important reasons, (this has been extensively discussed in other AF 447 threads.)

In the approach to the stall, the SOP is to apply TOGA power, lower the nose and minimize altitude loss. This still applies! The standard response to a full stall is to first get out of the stall and that means reducing the AoA to below the wing's stall AoA, then recovering by (gently!) controlling the loss of altitude and re-applying thrust as needed.

For some here who still don't appear to comprehend these things and who won't and can't support their recent statements that recovery from a full stall in transport category aircraft from cruise altitude, (as occurred here), takes "3500ft" or "7400ft", unloading the wing to reduce the AoA to below the stall AoA takes an enormous amount of altitude, and, while stalled, the altitude loss is extremely high, again as seen in the data.

Last edited by PJ2; 1st Apr 2012 at 16:43.
PJ2 is offline  
Old 1st Apr 2012, 16:34
  #1183 (permalink)  
PJ2
 
Join Date: Mar 2003
Location: BC
Age: 76
Posts: 2,485
Received 1 Like on 1 Post
machinbird;

In your response to T-Vasis:
  1. They mis-applied UAS procedures applicable to lower altitudes.
  2. They were distracted by a roll PIO to such an extent that they lost track of what was happening with the aircraft.
A third possibility, (perhaps a sub-possibility from either of the two above that you've mentioned), may be the PF's relative inexperience with high altitude manual flight, (in Alt 2 Law, roll is more sensitive than pitch), resulting in an unintended stronger pull on the stick than he desired, which he then began wrestling with at the same time he wrestled with (and nicely got under control) the roll oscillations. The two "stall warning" blips surprised both crew members, (What was that? - PM), but of course both warnings were legitimate as the AoA for the ECAM Stall Warning had been momentarily exceeded. Subsequent stick and pitch actions are less understandable but obviously plausible to the crew. Why?
PJ2 is offline  
Old 1st Apr 2012, 17:08
  #1184 (permalink)  
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 82
Posts: 1,454
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by PJ2
A third possibility, (perhaps a sub-possibility from either of the two above that you've mentioned), may be the PF's relative inexperience with high altitude manual flight, (in Alt 2 Law, roll is more sensitive than pitch), resulting in an unintended stronger pull on the stick than he desired, which he then began wrestling with at the same time he wrestled with (and nicely got under control) the roll oscillations. The two "stall warning" blips surprised both crew members, (What was that? - PM), but of course both warnings were legitimate as the AoA for the ECAM Stall Warning had been momentarily exceeded. Subsequent stick and pitch actions are less understandable but obviously plausible to the crew. Why?
PJ2
You will get no argument from me here although IMHO this belongs under (2)-They lost track of the aircraft due to roll control problems.
(in Alt 2 Law, roll is more sensitive than pitch)
Your observation on the force mis-match between proper pitch and roll inputs is significant from an aircraft handling POV. This is an undesirable combination.
Machinbird is offline  
Old 1st Apr 2012, 17:17
  #1185 (permalink)  
PJ2
 
Join Date: Mar 2003
Location: BC
Age: 76
Posts: 2,485
Received 1 Like on 1 Post
Hi Machinbird;

Re, roll sensitivity vs pitch in Alt 2 Law and your observation, "This is an undesirable combination. "

No, the difference is a matter of degree, not of characteristic. Both are eminently controllable but the flight controls also respond to large, quick inputs just as any aircraft would. These inputs were, for whatever reason and by all accounts, very large and very quick...sufficiently so as to cause the stall warning to trigger twice. Again irrespective of the reasons which may be found in understanding of high-altitude flight, training, experience, HF and technical/aircraft, this qualifies as mishandling the airplane. 'Why', is, as we many realize, is the question, which implies at this stage nothing regarding the PF or the airplane or ?, except a need to understand.
PJ2 is offline  
Old 1st Apr 2012, 17:45
  #1186 (permalink)  
 
Join Date: Jun 2011
Location: france
Posts: 760
Likes: 0
Received 0 Likes on 0 Posts
Snoop Human lifes are not screws...

Originally Posted by lomapaseo
99.99966% free of defects I have no idea to what this applies
Congratulations ! Never use a number without to know exactly which reality it covers. specially when it is probality or statistics.

PJ2 gave us unvolontary an opportunity to show that. When he used the number 99.9% it was a synonymous of high safety in his mind , as it is in horoscope or lottery, and tried to sell us some sterilized speech. In the cockpit, it would have his place, but we are here on the ground, all together, to get a little smarter with higher air safety, after AF447

I immediatly choosed to show what was wrong, and applied 99.9% to flight time, as he was in the defender's position, and the result was 67 hours safe vs 4 min crash, which is very unsafe.

Originally Posted by john_tullamarine
The gold standard is Six-Sigma - 99.99966% free of defects
Continuing this way, with 99.99966% free of defects, it means 3.4 / 1 000 000 defects.
For 4 minutes crash, you have 19 608 hours safe (in his whole life, PJ2 has flown around 20 000 hours)
For 1 minute crash, 4 902 hours are safe...
roulishollandais is offline  
Old 1st Apr 2012, 18:09
  #1187 (permalink)  
 
Join Date: Jun 2009
Location: florida
Age: 81
Posts: 1,611
Received 59 Likes on 19 Posts
Roll PIO and such

TNX for the support, PJ. Ya gotta head south this summer and sip a brew on my deck in Colorado. same for the 'bird.

Seems the 'bird is still positing a roll PIO and concentration on that while pulling back on the stick. The jet appears to have done a slow turn to starboard until impact, regardless of pilot stick commands. Can't find any trim for roll in the 'bus manuals you have provided, but looks like the jet simply commands zero roll rate if you let go of the stick in the roll axis. Is that right? My little jet had that "hat switch" on top of the stick, so you could actually command some roll rates even with "hands off". Same for baseline gee.

I fully understand the lack of training in post-stall recovery in the actual airplane, especially at high altitude. I also understand that many pilots have a problem recognizing the mach buffet compared to stall entry indications unless they have experienced both in a real airplane, but seems to me that a sim could implement some "shakers" and "buzz" things to help. My bent wing experience before the Viper helped me to see the difference, and yeah, it was "feel" and "touch". OTOH, my straight wind experience in two jets that could reach the critical mach without being in a steep dive was more interesting - wing rock, aileron buzz and even aileron reversal due to the shock wave effects, nose tuck that could not be overcome without speed brakes and reduced power ( elevator couldn't work due to the shock wave). Not fun at all.

After two years here, I am leaning back to my original position about the jet being in a stall all the way down. Not the classic "deep stall" as we see in the Viper and the T-tail airliners, as I originally suspected. Seems the 'bus has plenty of nose down pitch authority even with the THS cranked to the stop.

I still have trouble believing it would take more than 10,000 feet to recover from the stall they were in. Speed was above 100 knots actual dynamic pressure, and just reducing the AoA to zero for a few seconds should have produced useable lifties from the wings. So I figure a recovery in less than a minute and at 20,000 feet or so. The lower the plane got, the easier the recovery due to reduced mach and increased air density.

The mass of the airliners was a lot more than anything I ever flew, so I can imagine things taking longer, but not 35,000 frigghin' feet. I also understand that entry to an unusual flight condition would present problems recovering before getting into real trouble. Good old momentum and such. We called it "overshoot", but our control surfaces were lots larger for our gross weight than any commercial airliner.

Am waiting for the "final" report and recommendations. Will be disappointed if the human factors are not addressed, and not just training, but the displays.
gums is offline  
Old 1st Apr 2012, 18:16
  #1188 (permalink)  
 
Join Date: Feb 2011
Location: Nearby SBBR and SDAM
Posts: 875
Likes: 0
Received 0 Likes on 0 Posts
Man-machine interface

Hi,

PJ2, this characteristic was intentionally implemented in the A/C? If so, why? If not, it could be improved?

For example, take into account Altitude as an input parameter in order to "help" the crew perform better the (less common) cruise level manual handling? That can occur in adverse conditions (severe turbulence, degraded (intermittent) avionics, etc.)

How you compare the difference (quantifying) in sensitivity (roll x pitch in Alt II) versus Alt I (if there is) and versus NL. The reason of my question is:

To understand "how different" was the plane PF "received" when was "inserted" in the loop and started to apply the corrections he decided (after processing the inputs he is receiving).

The "decision making" PF made (his first reaction) is unknown, obviously. But, we can infer, something important (to him) under the conditions he was facing, led him to.
RR_NDB is offline  
Old 1st Apr 2012, 18:46
  #1189 (permalink)  
 
Join Date: Oct 2009
Location: UK
Posts: 1,270
Likes: 0
Received 0 Likes on 0 Posts
I concur with your description of the "feel" of an aircraft in #1162.
In Normal Law - there is no such feeling of how much control surface deflection was required to satisfy your request.
Can't find any trim for roll in the 'bus manuals
Correct.
In Normal Law, it is trimmed automatically by deflecting the ailerons sufficiently so that at stick release there is zero roll rate.
In ALT LAW it's like a Boeing in roll. Stick deflection demands a proportional aileron deflection. The only trim available is rudder - to yaw the wing sufficiently so that aileron deflection is not required to hold the wing level. The roll rate is faster.

In Alt Law, Pitch control "feels" the same as Normal Law - you select a delta g, it changes attitude and stays there on stick release - automatically trimming as the speed washes off.
rudderrudderrat is offline  
Old 1st Apr 2012, 18:48
  #1190 (permalink)  
 
Join Date: Jun 2011
Location: france
Posts: 760
Likes: 0
Received 0 Likes on 0 Posts
Snoop Origin of the 7400 FT for recover

Hi PJ2,

Warning : Machinbird called many times to high vigilance about this calculation. I agree totally to the calculation but also to the warnings, and here is copy of his last warning.
Originally Posted by Machinbird
Dutchroll, these were speculative numbers for a last minute escape from the full stall. The pullout is dependent on achieving near maximum performance, and the stall recovery altitude/time is entirely speculative. The emphasis should be on speculative. Remember, this is for near maximum performance. Without an AOA indicator, I see no way to come close to these numbers. OK465 seems to believe it will be a problem teaching people when and if to add some power during pullout to improve performance. He is probably correct.

My intent in coming up with these speculative pullout figures is to remind people who may be in similar situations to not give up! You might think you are toast, but keep thinking and keep flying to the limits of your ability. You just might get a pleasant reward. The light at the end of the tunnel is not always a train.
You will find most of the details of the 7400 FT calculation, iin these Thread 7, posts :

- Hazelnuts39 #945 (phugoid)
- Machinbird #950 "10,000 feet is about the last point one could hope to begin recovery"
- Machinbird #955
- Hazelnuts39 #960
- Machinbird #962

The result is :
with begin of recovery at 10 000 FT
-5 000 FT (max) (for unloading the wing)
- good performance with 0.15% thrust for recovery :
loss of height = FL100-FL76)= 2 400 FT

Finally the total loss of height is - 5 000 - 2 400 = - 7 400 FT

roulishollandais is offline  
Old 1st Apr 2012, 19:01
  #1191 (permalink)  
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 82
Posts: 1,454
Likes: 0
Received 0 Likes on 0 Posts
Continuing this way, with 99.99966% free of defects, it means 3.4 / 1 000 000 defects.
For 4 minutes crash, you have 19 608 hours safe (in his whole life, PJ2 has flown around 20 000 hours)
For 1 minute crash, 4 902 hours are safe...
Fortunately, due to redundancy concepts, we can have small failures and not have an accident. Our actual airline accident rate on an hourly basis is far better than 6 sigma. (For most airlines at least)

Compare that with the overall Navy accident rate during most of my career--3.5 to 2.5 accidents per 10,000 flight hours. Makes one wonder if you will personally get involved in the statistics during your career. Then add combat hazards to that.
Machinbird is offline  
Old 1st Apr 2012, 19:40
  #1192 (permalink)  
 
Join Date: Feb 2011
Location: Nearby SBBR and SDAM
Posts: 875
Likes: 0
Received 0 Likes on 0 Posts
Kapton

Hi,

Machinbird:


Did you investigated Kapton (wiring) related incidents, more frequent (AFAIK) in naval aviation?

Posted reply on "HF keying during refueling" thread (on F4 fuel probes) and sent PM on "unloading the wing on an airliner"
RR_NDB is offline  
Old 1st Apr 2012, 20:12
  #1193 (permalink)  
PJ2
 
Join Date: Mar 2003
Location: BC
Age: 76
Posts: 2,485
Received 1 Like on 1 Post
roulishollandais;

First, in your post #1148 you have completely missed my point in favour of making your own. Further, in your choice to parse the metaphorical expression, "99.99%" rather than try to understand what was being conveyed by the post you have demonstrated a complete absence of understanding of how flight safety works and why this industry is so remarkably safe and you have refused to engage in a pleasant dialogue which would have led to further discussion and perhaps even further comprehension.

My "99.99%" was a metaphor...a figure of speech indicating high, versus medium or low correlation between SOPs and their adherence, and the very high safety levels of our industry. You took this expression literally, applied mathematics to a metaphor and drew precise and entirely incorrect conclusions which have no basis in the kind of activities, processes and preventative strategies which bring about such high levels of safety in this industry. Should we briefly examine a counterexample, you take the "ten to the minus ninth" standard and apply it to one variable, (my number of hours flying) and ridiculously try to extend such "chances" to the industry. That's not really how it all works, you see.

Your approach utterly fails to take into account this complex and effective safety system which is decades old and to which many engineers, human factors specialists, pilots' associations, manufacturers and airlines have immeasurably contributed and so, beyond a detail of what "99.99" means statistically, the point you are trying to make fails to make any contribution to a broader understanding of what is behind the millions of hours of unremarkable flight and why this accident has so captured the imagination and interest of so many.

Regarding your calculation of 7400ft, you have set up a straw man case which bears no relationship to the discussion at hand yet the outcome for your straw man argument, "7400ft" is applied to the case, again at hand. I don't know how you do that and still claim some correlation between the two but of course you are free to do as you please notwithstanding relevance to the discussion.

For your "model recovery" (which may have basis in fact but which, again, bears no relationship to the present exercise), you begin the recovery at FL100. If one approaches (not enters) the stall at FL100, recovery may occur within your calculated altitude if the recovery from the approach-to-stall is handled smartly. In fact in simulator exercises, typical altitude loss using the "Approach to Stall" procedures was held to between 500 and 800ft depending on a number of factors. Further, I suspect that had these procedures been applied just prior to the apogee, (lowered pitch to 5deg below the horizon), TOGA thrust, respect the stall warning (in Alt law), the event may not have developed into a full stall. Once the AoA was increasing to 30 and 40 degrees, that procedure would NOT work and recovery from the stall would be necessary, which means pointing the nose down to between 15 and 20 degrees ND and accepting the extremely high rate of descent.

However, the simulator case at hand and our real case, AF447 was in full stall, and at FL100 was still descending at approximately 17000fpm with an AoA of 45deg. Your case and your argument is therefore wholly non-applicable; the aircraft is not going to recover in "7400ft".

You may pit your willingness to argue minutae such as "99.99%" against the experience of several here who know their stuff and against the numerous simulator exercises all of which run counter to your notions of recoverability. That, as you say, is your choice. But I submit that the issue here is not one of being right come what may but is one of understanding both the aircraft and high-altitude flight and what needs to be done by the crew to swiftly unload the wing to reduce the AoA below the stall when a transport aircraft is in a full stall at cruise altitudes.

It is completely incorrect to suggest that a fully-stalled airliner at cruise altitudes of the kind we are discussing here will recover from such stall with a 7400ft loss of altitude from said altitude. An appreciation of the subtleties of this very dynamic set of circumstances would go a long way in support of a collegial exchange of views.

The only case in which your understanding may be marginally in accord with the facts is in strictly controlled flight test conditions where the approach to the stall is part of a test regime...note I said "Approach to the Stall" because NO ONE intentionally stalls a transport aircraft at any altitude any more, period. The Flight Test manual for these exercises states that such tests will be done at FL140 or higher. The one case which has occasionally been introduced here is the Perpignan case but this crew collectively decided to approach the stall test on final at 3000 AGL and rushed the process. The recommended height for such tests is for a reason, and the stuck AoA vane is one clear reason why.

Last edited by PJ2; 2nd Apr 2012 at 00:15.
PJ2 is offline  
Old 1st Apr 2012, 21:11
  #1194 (permalink)  
 
Join Date: Aug 2011
Location: Grassy Valley
Posts: 2,074
Likes: 0
Received 0 Likes on 0 Posts
It was mentioned that "Approach to STALL" recovery at Colgan prior to, no altitude loss was the goal. You mentioned a recovery with ND; at Colgan, losing more than 100 feet was disqualifying. I tend to agree with your presentation, from 350, any recovery from Stall will use up more than half the total altitude, and may not even be possible, especially if no AoA indicator to 'help' guard against secondary STALL?

I cannot understand why the focus is on something that is at best tangential, and when grumpy, totally irrelevant. To have lost control in the first place makes the STALL recovery argument silly. Whatever the cause, to deplete her energy in that fashion suggests that it will not be suddenly available to be careful with that which may be regained in a 20k dive?
Lyman is offline  
Old 1st Apr 2012, 21:46
  #1195 (permalink)  
 
Join Date: Feb 2011
Location: Nearby SBBR and SDAM
Posts: 875
Likes: 0
Received 0 Likes on 0 Posts
Redundancy

Hi,

Machinbird:

Actually a good "Redundant Design" can support (degrading) even major failures.

Our human body is an example: We are adequately redundant: Duplicated lungs, Kidneys, arms, etc. The Designer ( implemented this SAFETY feature extensively in nature.

The "Fault Tolerance and Graceful Degradation" was certainly the major achievement of this "Design Approach", actually by " Species Evolution".

On big Systems we may comment Fukushima disaster on that:

Their "APU" failed completely (when they most needed it) after the "protections" were triggered (by the G's) and the ABSOLUTELY NECESSARY cooling of the reactors ceased what lead to a "Thermal Runway".

They had to use Chinooks (risking) during subsequent days at the emergency peak of the event.

Why it failed? The March 11 wave was taller (than the expected maximum). The "equipt" operated as per design. . Like the 747 cargo door issue (flt 811) and a multitude of other sad examples.

The Engineers responsibility is enormous: Quality (the result of the design) depends totally from a good Specification.

In aviation, as many here commented the pilot must operate "inside" the "machine limits". Example: The Pitot's current limitations. The first threat F-GZCP "received" was the path (with a "last minute" slight deviation) towards a WX other crews deviated. This exceeded the limits of an important element of the System, (Pitot's) triggering a cascade of events. A rare chain so complex, being regarded as directly related to (complex and "subjective") Human Factors.

The Redundancy applied in modern airliners is carefully studied to the Industry requirements.

And frequently reduce the consequences (after major failures) or even transform potential serious accidents in "manageable incidents".

It can tolerate major failures? Examples abound. And the crew (a good preparation and integration to the equipment) is a VITAL "part" of the System (The effective aircraft: System+crew).

Gen. Chuck Yeager in October 1947 successfully landed his bird (X1) after facing a TOTAL electrical failure just after separating from "mother ship".

The fuel valve" (a redundant safety feature) was an important factor to save him and the bird. And the toll (of the failure) was put in him. Who accomplished (partially) the mission. Reducing it to an incident.

PS

One magnificent example was Capt. Sully achievement. (I remember when i crossed Hudson river in a rented motor home). He even flew "offset" the bridge aligning the bus when in the short final. The comment of his wife after learning the fact shows how Sully was the perfect "element" of a well designed System, his bird an the crew.
RR_NDB is offline  
Old 1st Apr 2012, 22:21
  #1196 (permalink)  
 
Join Date: Dec 2010
Location: Middle America
Age: 84
Posts: 1,167
Likes: 0
Received 0 Likes on 0 Posts
PJ2,

I am sorry my mention of Six Sigma and its goal of 99.9966% free of defects has been misinterpreted by some and not understood by others. To somewhat clarify things, Six Sigma is a business management strategy to improve the quality of process outputs by identifying and removing the causes of defects (errors) and variability in processes. It is not confined to just improvements of manufacturing processes. In the airline industry, there are many processes which in one way or another contribute to the safety aspects of flying, which is very, very good considering the complexities.

Processes usually do not perform as well in the long term as they do in the short term and there are many reasons why this is often the case. Figuring out why is the task and identifying improvements is the goal. To accomplish identification and zero in on meaningful improvements, the Six Sigma process has over 30 management and method tools that can be used. Most do not require a statistician background, just good common sense and knowledge of the process to be improved. For example, the generation of a key list or lists is a tool.

Now pertaining the A-330, there is a memory list for pilots to memorize regarding the occurrence of unreliable airspeed. It defines what a pilot should do if UAS is encountered and as I recall, it emphasizes low altitude critical situations, takeoffs and landings while also mentioning altitudes above 20k feet. It does not mention the words "at cruise" or "high mach". Now in cases of UAS at cruise and high mach, most pilots have figured it out, what to do to prevent LOC, but more recently, not all have done so. Would an improvement to the memory list to include what to do "at cruise" help future situations that might occur? This is just a small example of a Six Sigma tool being used to improve the output of a process. Then one can think about training processes and what can be improved there. People, generally bean-counters, say training cost a lot of money, it does. However, spending some extra money can result in much greater savings if errors can be prevented. GE, a big Six Sigma advocate had reaped over $1B in savings using the Six Sigma process, and that was 9 or 10 years ago.

It is interesting to note that at least two airlines do use the process to some degree with reported good results, Air Canada and Alaska Airlines. Many other companies in the aerospace industry use the process, Boeing, Honeywell, GD, Lockheed Martin, Northrop Grumman to name a few. Even the USAF, USN and USMC are using the tool to improve their processes.

That is what I meant by Six Sigma...
Turbine D is offline  
Old 1st Apr 2012, 23:13
  #1197 (permalink)  
 
Join Date: Jun 2009
Location: Bedford, UK
Age: 70
Posts: 1,319
Received 25 Likes on 14 Posts
I shall have to read these posts in slow time. in the meantime however, let me say that in no branch of science or engineering have i ever heard or had recourse to 6 sigma confidence levels. that is nonsense. however is a 20k margin for altitude loss for 447 reasonable assuming cognition started when the captain returned?
Mr Optimistic is offline  
Old 1st Apr 2012, 23:20
  #1198 (permalink)  
 
Join Date: Oct 2011
Location: Lower Skunk Cabbageland, WA
Age: 74
Posts: 354
Likes: 0
Received 0 Likes on 0 Posts
PJ2 and the 99.99%

To the Fabulous PJ2,
I think part of the problem is a severe language barrier. Just a thought.
Organfreak is offline  
Old 1st Apr 2012, 23:33
  #1199 (permalink)  
 
Join Date: Jun 2009
Location: florida
Age: 81
Posts: 1,611
Received 59 Likes on 19 Posts
Gee and roll rate trim and recovery

Thanks, Rudder, it's what I thot. Our simple FBW could be trimmed for a gee ( plus 3.5 gee and about minus 1 gee), which several guys did to have a zero gee hands-off stick for gaining energy. Roll was likewise, and a hands-off normally was a zero roll rate command, but we could manually trim to about 150 deg/sec roll rate command ( or something like that).

I still don't agree with PJ that I couldn't recover in 10,000 or 15,000 feet. Give me a chance in the sim and I'll do my best. The jet had plenty of dynamic pressure, just a bit below normal approach speed. With gear up and some added power, reducing the AoA to zero should have resulted in a significant increase in speed and then a careful, gentle pull back up to level. Screw the mach/overspeed stuff. The jet is tough, and seems very stable.
gums is offline  
Old 1st Apr 2012, 23:33
  #1200 (permalink)  
 
Join Date: Jun 2009
Location: Bedford, UK
Age: 70
Posts: 1,319
Received 25 Likes on 14 Posts
Yes i have heard of lean 6 sigma. Toyota inspired no doubt. management texts are often scientifically illiterate so dont hang your hat on a $10 text.
Mr Optimistic is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.