Technical Faults Cause Most Accidents
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Technical Faults Cause Most Accidents
There is a very interesting article in Flight today. Apparently technical malfunctions have overtaken CFIT as the major cause of air accidents. Food for thought for those who tirelessly advocate pilotless aeroplanes on this forum and elsewhere?
confundemus
confundemus
Iconoclast
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Numbers. What do they mean?
To: Pirate
Considering the number of accidents attributed to system malfunctions no aircraft has ever met the 10 9 requirements of system failures causing loss of life.
Apparently technical malfunctions have overtaken CFIT as the major cause of air accidents.
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As the statistical sample is so small - can you make any relevant assumptions at all from it?
Mechanical problems - in some cases known to have resulted from maintenance mistakes - were the trigger in 11 accident sequences in 2003 that resulted in the deaths of 295 people.
CFIT was responsible for 10 fatal accidents and 243 deaths - the second worst accident category.
Too mean to buy a long personal title
The more relevant question must be how many accident sequences did technical errors and CFIT contribute to in past years? Overall accident numbers are down. If a large part of this is because CFIT is well down, then the word "overtaken" is a bit misleading.
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There is no such thing as a single accident cause. Human error is always in there somewhere. Such reports as CFIT and Technical problems causing accidents is simplistic at best and misleading at worst.
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I guess that all this wouldn't have anything to do with the fact that.........
In Eurpoe there are fewer than ever Licenced Aircraft Enginers, more aircraft than ever and Airlines are using "partially" (A3) Licenced certifiers???????
Would it????
PLM
In Eurpoe there are fewer than ever Licenced Aircraft Enginers, more aircraft than ever and Airlines are using "partially" (A3) Licenced certifiers???????
Would it????
PLM
Do a Hover - it avoids G
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Human error is always in there somewhere
There is no such thing as an act of God causing an aeroplane accident. Only humans design, maintain and operate aeroplanes so only humans cause the accidents they experience.
From 1950 to 1970 if you looked at the causes of accidents they were (very very roughly) 70% pilot error and 30% technical. The operational error ones like mid airs and ATC screw ups were less than 1%.
Then as newer designs required less piloting skill and compensation for poor handling or poor cockpit design the pilot error category has fallen steadily - at least in mainstream passenger operations.
Being realistic it will always be harder to avoid aircrew based errors from causing accidents just because they are up their on their own and so a finite resource to deal with poor design or the aftermath of the day to day mistakes we all make at work.
In the hangar (in theory) there is not the same finite and limited resource to check, double check, back up and so on. BUT commercial judgement re costs will always tend to err towards fewer people or less able people until events force a change.
Nothing very profound in any of this I am afraid.
But the bottom line is the whole safety thing is creeping better, however it breaks down in detail. Which has to be good.
PLM has made a valid point. Meanwhile the beancounters do risk assessments and refer to 'the acceptable number of hull losses'
Something about robbing Peter to pay Paul lets hope that safety is always named Paul
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Safety engineers prioritizing service Bulletins Iomapaseo? I don't think so. Who exactly writes the Service Bulletins and who asks for them to be produced in the first place?
Typical priority instructions followed by development engineers to assess Service Bulletins for incorporation are generally headed by something like "Does this problem have a safety implication" followed closely by "Do we have this problem in our fleet?" In the regulatory bodies are engineers who may prioritize an SB by making it mandatory, but I've never encountered any mandatory SB that we hadn't already placed under action long before the regulators made it mandatory.
There are operators that have lower standards of course - you can find them on the banned lists for the USA and many European nations if you want to avoid flying with them. There are also plenty of operators that outsource all maintenance and rely on their contracted amintenance organization to recommend SBs. For this purpose the mandatories stand out easily from the crowd, but nevertheless nearly all contracts include non-mandatory SBs that address problems that the customer airline are experiencing.
The most important factors in improving technical standards have been reliabilty programmes and Maintenance Steering Group (MSG) based Maintenance Planning Documents (MPDs) that concentrate effort and reduce both workload and downtime. The latest maintenance schedules now include comprehensive Corrosion Prevention and Control Programmes (CPCP) - with prevention being the most important factor.
One area that holds plenty of room for improvement right now - and Lu Zuckerman would no doubt back me up - is at the design stage, Structures are fairly well understood but there are many system designs out there that lack full and accurate risk assessments. One example is the original B737 rudder system design that the manufacturer insisted was satisfactory until the third total loss; another good example is the widespread use of stabilizers that rely on a single screw jack so that a single point failure can (and at least once did) cause a hull loss. Generally though, good progress is being made in reducing the overall loss rate.
BTW what about that Airbus that got down safely after a total loss of all flight controls when it was hit by a SAM? Although all the hydraulic systems failed (how could it be otherwise?) the structure held despite the severe damage caused by a missile exploding in the fuel tank and the susequent fire. Most of all though, the crew were bloody marvellous! Human error might cause a lot of accidents but human efforts may also prevail in an otherwise hopeless situation. Never rule out the human element, either way.
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Through difficulties to the cinema
Typical priority instructions followed by development engineers to assess Service Bulletins for incorporation are generally headed by something like "Does this problem have a safety implication" followed closely by "Do we have this problem in our fleet?" In the regulatory bodies are engineers who may prioritize an SB by making it mandatory, but I've never encountered any mandatory SB that we hadn't already placed under action long before the regulators made it mandatory.
There are operators that have lower standards of course - you can find them on the banned lists for the USA and many European nations if you want to avoid flying with them. There are also plenty of operators that outsource all maintenance and rely on their contracted amintenance organization to recommend SBs. For this purpose the mandatories stand out easily from the crowd, but nevertheless nearly all contracts include non-mandatory SBs that address problems that the customer airline are experiencing.
The most important factors in improving technical standards have been reliabilty programmes and Maintenance Steering Group (MSG) based Maintenance Planning Documents (MPDs) that concentrate effort and reduce both workload and downtime. The latest maintenance schedules now include comprehensive Corrosion Prevention and Control Programmes (CPCP) - with prevention being the most important factor.
One area that holds plenty of room for improvement right now - and Lu Zuckerman would no doubt back me up - is at the design stage, Structures are fairly well understood but there are many system designs out there that lack full and accurate risk assessments. One example is the original B737 rudder system design that the manufacturer insisted was satisfactory until the third total loss; another good example is the widespread use of stabilizers that rely on a single screw jack so that a single point failure can (and at least once did) cause a hull loss. Generally though, good progress is being made in reducing the overall loss rate.
BTW what about that Airbus that got down safely after a total loss of all flight controls when it was hit by a SAM? Although all the hydraulic systems failed (how could it be otherwise?) the structure held despite the severe damage caused by a missile exploding in the fuel tank and the susequent fire. Most of all though, the crew were bloody marvellous! Human error might cause a lot of accidents but human efforts may also prevail in an otherwise hopeless situation. Never rule out the human element, either way.
**************************
Through difficulties to the cinema
Iconoclast
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Everyone is right and some of you are wrong.
It is true that the human factor no matter where it is plays a great deal as the underlying causes of accidents. However once the accident has occurred and once the causes are established it is completely out of the hands of the “safety engineers”.
Whether the necessary corrective action takes place or it is not effected is in the hands of the certification authorities. I can only speak for the FAA and this is what they do. First of all the FAA is more interested in preserving their relationship with the airlines than they are in protecting the flying public. That is the responsibility of the NTSB. Once the NTSB determines the cause of an accident they will tell the FAA what must be done in order to prevent further accidents from the same cause.
Once the FAA knows what must be done they perform a cost benefit analysis. In essence they will determine the financial impact on the airlines in order to make the changes and then they will determine the human cost in a similar accident. The cost of a human life is 2.5 Million dollars US. They will multiply this by the number of seats in a similar aircraft. If the total in human lives is greater than the financial impact on the airlines they will recommend the change. If the cost in human lives is less than the cost of making the change they will rule against the change.
I hope I got it right as it is almost midnight here.
If you want me to expound on the problems during the design stage i can do that as well but only after I get a bit of sleep.
Whether the necessary corrective action takes place or it is not effected is in the hands of the certification authorities. I can only speak for the FAA and this is what they do. First of all the FAA is more interested in preserving their relationship with the airlines than they are in protecting the flying public. That is the responsibility of the NTSB. Once the NTSB determines the cause of an accident they will tell the FAA what must be done in order to prevent further accidents from the same cause.
Once the FAA knows what must be done they perform a cost benefit analysis. In essence they will determine the financial impact on the airlines in order to make the changes and then they will determine the human cost in a similar accident. The cost of a human life is 2.5 Million dollars US. They will multiply this by the number of seats in a similar aircraft. If the total in human lives is greater than the financial impact on the airlines they will recommend the change. If the cost in human lives is less than the cost of making the change they will rule against the change.
I hope I got it right as it is almost midnight here.
If you want me to expound on the problems during the design stage i can do that as well but only after I get a bit of sleep.
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To what degree then can we equate technical failures with financial constraints? If money was no object, human factors and the limits of our understanding of the technology still remain.
As for the FAA cost benefit analysis influenced by multiples of pax rather than hull loss, does this make smaller aircraft less safe? I fly freighters, does nobody care?
As for the FAA cost benefit analysis influenced by multiples of pax rather than hull loss, does this make smaller aircraft less safe? I fly freighters, does nobody care?
I'm afraid that some of you are being misled by so called FAA detractors for the sake of making a point about nobody but we care
You see there is no such thing as a cost benefit analysis or tombstones to count per plane when it comes to fixing things that are broke.
The regulations which govern the design are your FAR/JARs which you choose to accept when you take flight.
Things that are found to be wrong after the product is built come under another regulation which is part 39 continued airworthiness . The intent of this regulation is to bring the original product back into compliance in a time frame that does not contribute to the historic overall risk for the product line e.g.: part 25 aircraft etc..
Thus big problems get worked much faster than little problems. However, any operator can choose to incorporate fixes at a faster rate.
As far as incorporation rates go, the authorities do track these even as voluntary. Where compliance is not assured in a reasonable time (some operators just don't get the word) than mandatory compliance is required.
Of course there is some flexibility under voluntary compliance and that is often the case when an operator proposes an alternate means of compliance (offer evidence that the problem is addressed because of his operation or practices)
You see there is no such thing as a cost benefit analysis or tombstones to count per plane when it comes to fixing things that are broke.
The regulations which govern the design are your FAR/JARs which you choose to accept when you take flight.
Things that are found to be wrong after the product is built come under another regulation which is part 39 continued airworthiness . The intent of this regulation is to bring the original product back into compliance in a time frame that does not contribute to the historic overall risk for the product line e.g.: part 25 aircraft etc..
Thus big problems get worked much faster than little problems. However, any operator can choose to incorporate fixes at a faster rate.
As far as incorporation rates go, the authorities do track these even as voluntary. Where compliance is not assured in a reasonable time (some operators just don't get the word) than mandatory compliance is required.
Of course there is some flexibility under voluntary compliance and that is often the case when an operator proposes an alternate means of compliance (offer evidence that the problem is addressed because of his operation or practices)
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The FAA cares????
To: Lomopaseo
When I was working as Reliability manager on a major Airbus program I discovered two design faults that could lead to the loss of the aircraft. I notified the large aircraft certification office in Seattle telling them of the problem. I sent the first letter with no response. I sent a second letter reiterating the problems. Two months later I received a letter thanking me for my input. In a second letter from the FAA I was told that they had spoken with the DGCA who told them that the problems had been corrected.
I contacted several friends that were still on the program and they indicated that the design had not been changed. When the various members of the consortium were made aware of the problems they took no action in order to avoid the cost of the redesign. They never mentioned the problems to Airbus and when they were made aware of the problems they took no action and by that time there were over 30 models of that aircraft flying in revenue service. I contacted the FAA and when they took action the Vice President and Chief Program manager were fired. The design was never changed and that model of Airbus is still flying with the design defects. And as far as the FAA not performing cost benefit analyses you are totally wrong.
I belong to the Lawyer Pilots Bar Association and in writing my book FINGER TROUBLE I contacted many of the lawyers in the organization for background information and they said that in effect you are wrong. When all of the Robinson R-22s were losing their rotors the NTSB fought tooth-and-nail to lift the certification for the helicopter and the FAA refused although 27 R-22s had been effected and each one had two souls aboard.
In other words stop being so defensive.
To: Nineiron
Even though you fly freighters the aircraft you fly is one of many models of the basic aircraft. If a change is to be made it will be incorporated in your aircraft. However if in the modification to your aircraft the offending part had been removed during the mod then your aircraft would not be effected.
When I was working as Reliability manager on a major Airbus program I discovered two design faults that could lead to the loss of the aircraft. I notified the large aircraft certification office in Seattle telling them of the problem. I sent the first letter with no response. I sent a second letter reiterating the problems. Two months later I received a letter thanking me for my input. In a second letter from the FAA I was told that they had spoken with the DGCA who told them that the problems had been corrected.
I contacted several friends that were still on the program and they indicated that the design had not been changed. When the various members of the consortium were made aware of the problems they took no action in order to avoid the cost of the redesign. They never mentioned the problems to Airbus and when they were made aware of the problems they took no action and by that time there were over 30 models of that aircraft flying in revenue service. I contacted the FAA and when they took action the Vice President and Chief Program manager were fired. The design was never changed and that model of Airbus is still flying with the design defects. And as far as the FAA not performing cost benefit analyses you are totally wrong.
I belong to the Lawyer Pilots Bar Association and in writing my book FINGER TROUBLE I contacted many of the lawyers in the organization for background information and they said that in effect you are wrong. When all of the Robinson R-22s were losing their rotors the NTSB fought tooth-and-nail to lift the certification for the helicopter and the FAA refused although 27 R-22s had been effected and each one had two souls aboard.
In other words stop being so defensive.
To: Nineiron
As for the FAA cost benefit analysis influenced by multiples of pax rather than hull loss, does this make smaller aircraft less safe? I fly freighters, does nobody care?
I am not wrong about cost benefit analysis when it comes to fixing things that are broke..
People with blinders just want to see things their way.
My statement stands as posted. Some folks may have bothered to read it
People with blinders just want to see things their way.
My statement stands as posted. Some folks may have bothered to read it
Iconoclast
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Sticking to my guns.
To: Lomapaseo
The following has been excerpted from the book Finger Trouble and is based on input from several aviation lawyers.
In the 747 explosion over the Atlantic, 230 passengers and crew were killed. The National Transportation Safety Board (NTSB) has ruled that the cause was the build-up of fuel vapors and the introduction of a non-specific ignition source. They implied that the ignition source could have been caused by a static discharge (which further implies that the elements within the tank were not properly bonded). Another source of ignition could have come from a wire with broken insulation (it was a known fact that early 747’s used a type of wire that was insulated with a material that was subject to cracking from atmospheric and environmental exposure). One other source of ignition could be from a lightning strike in conjunction with inadequate bonding. The reader should know that every commercial airliner is hit by lightening on the average one time each year.
Having experienced one explosion in a 747, the NTSB wants to prevent similar explosions, so they suggest that future tank explosions could be prevented, if the airlines would install nitrogen inerting systems in the fuel tanks of all of their respective aircraft. To do this, the airlines would have to down their aircraft for the time it takes to install the systems, losing the revenue generated by the aircraft. In addition to this, they will have to absorb the costs of the modification. To determine the economic feasibility of such an extensive modification the FAA would perform a cost benefit analysis. The FAA could easily determine the financial impact on the airline industry but what do they weigh this figure against?
They must weigh these costs against the value of the human lives that would be saved if the modification were incorporated. The reader can trot down to the local super market to determine the sale price of a dozen eggs or the discount price for a gallon of milk, but where does he or she go to find the manufacturers suggested retail price for a human being? He or she would have to look no further than the Department Of Transportation (DOT) in Washington, D.C. The DOT is the parent organization of both the FAA and the NTSB. The DOT uses, what else, a complex mathematical formula that takes into consideration all types of numeric input to include the gross national product figures for that fiscal year. The latest dollar value placed on an American citizen at the time of this writing is 2.7 million dollars. In running their calculation, the FAA bean counters multiply the 2.7 million dollars, by the 230 lives lost in the 747 explosion. This equates to six billion two hundred ten million dollars. They weigh one figure against the other and if it costs more to incorporate the fix in America’s airliners than the value of the human lives saved, the FAA will not recommend the modification. That sounds cold but that’s the way it’s done. No aircraft will be modified and as a result, the conditions that caused the first explosion are still waiting in the wings (excuse the pun), ready to manifest themselves in a second explosion. It might interest the reader to know that several other aircraft along with a lot of passengers were lost due to fuel tank explosions. But those other explosions occurred in aircraft that were not on the FAA registry, so they don’t count.
What are the possibilities that a second or third or maybe even a fourth or fifth 747 might explode causing massive loss of life. And, if a second, third or a fourth explosion were to occur, would the FAA recalculate another Cost Benefit Analysis. Compared with the FAA’s allowable frequency of 10-9, for a single system failure that can result in an aircraft loss, the probability of another explosion is quite high.
PERSONAL COMMENT: In some cases where there is public outcry or enough bad publicity the FAA will acquiesce and authorize the change.
The following has been excerpted from the book Finger Trouble and is based on input from several aviation lawyers.
In the 747 explosion over the Atlantic, 230 passengers and crew were killed. The National Transportation Safety Board (NTSB) has ruled that the cause was the build-up of fuel vapors and the introduction of a non-specific ignition source. They implied that the ignition source could have been caused by a static discharge (which further implies that the elements within the tank were not properly bonded). Another source of ignition could have come from a wire with broken insulation (it was a known fact that early 747’s used a type of wire that was insulated with a material that was subject to cracking from atmospheric and environmental exposure). One other source of ignition could be from a lightning strike in conjunction with inadequate bonding. The reader should know that every commercial airliner is hit by lightening on the average one time each year.
Having experienced one explosion in a 747, the NTSB wants to prevent similar explosions, so they suggest that future tank explosions could be prevented, if the airlines would install nitrogen inerting systems in the fuel tanks of all of their respective aircraft. To do this, the airlines would have to down their aircraft for the time it takes to install the systems, losing the revenue generated by the aircraft. In addition to this, they will have to absorb the costs of the modification. To determine the economic feasibility of such an extensive modification the FAA would perform a cost benefit analysis. The FAA could easily determine the financial impact on the airline industry but what do they weigh this figure against?
They must weigh these costs against the value of the human lives that would be saved if the modification were incorporated. The reader can trot down to the local super market to determine the sale price of a dozen eggs or the discount price for a gallon of milk, but where does he or she go to find the manufacturers suggested retail price for a human being? He or she would have to look no further than the Department Of Transportation (DOT) in Washington, D.C. The DOT is the parent organization of both the FAA and the NTSB. The DOT uses, what else, a complex mathematical formula that takes into consideration all types of numeric input to include the gross national product figures for that fiscal year. The latest dollar value placed on an American citizen at the time of this writing is 2.7 million dollars. In running their calculation, the FAA bean counters multiply the 2.7 million dollars, by the 230 lives lost in the 747 explosion. This equates to six billion two hundred ten million dollars. They weigh one figure against the other and if it costs more to incorporate the fix in America’s airliners than the value of the human lives saved, the FAA will not recommend the modification. That sounds cold but that’s the way it’s done. No aircraft will be modified and as a result, the conditions that caused the first explosion are still waiting in the wings (excuse the pun), ready to manifest themselves in a second explosion. It might interest the reader to know that several other aircraft along with a lot of passengers were lost due to fuel tank explosions. But those other explosions occurred in aircraft that were not on the FAA registry, so they don’t count.
What are the possibilities that a second or third or maybe even a fourth or fifth 747 might explode causing massive loss of life. And, if a second, third or a fourth explosion were to occur, would the FAA recalculate another Cost Benefit Analysis. Compared with the FAA’s allowable frequency of 10-9, for a single system failure that can result in an aircraft loss, the probability of another explosion is quite high.
PERSONAL COMMENT: In some cases where there is public outcry or enough bad publicity the FAA will acquiesce and authorize the change.
One needs to understand the difference between a prescribed existing rule (FAR/JAR 25.xxx, rulemaking (additional rules beyond that already prescribed) and continued airworthiness (the means by which the product maintains its original safety assumptions through service bulletins, maintenance actions etc.).
I don't need somebody's book to interpret this.
I don't need somebody's book to interpret this.
Iconoclast
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To: Lomapaseo
The means used to determine the compliance with FAA design guidelines which state the frequency of a system failure that would result in the loss of one or more lives be not less than 10 9 are a farce and equates to black magic and the manipulation of numbers. In the annals of commercial flight no aircraft has ever met those criteria. It took the loss of several B-737s due to the same cause before the FAA took any action. When an aircraft is downed due to a system failure the FAA does not go into the calculations that stated the design met design criteria. To do so would place the FAA in a position of having blindly accepting the figures from the manufacturer.
I don't know how long you have worked for the FAA but I have been in the position of determining the reliability and safety of aircraft and military systems since 1968. I have seen it all and it makes me sick. I have tried to change the system for a long time and have run up against a brick wall.
To; 747FOCAL
If pilot error can be proved directly or by assumptions (inability to recover the aircraft or possibly inability to come up with a final cause) the manufacturer, the operator and suppliers absolve themselves of any responsibility. That leaves the lawyers to go aftter the pilots estate.
(the means by which the product maintains its original safety assumptions
I don't know how long you have worked for the FAA but I have been in the position of determining the reliability and safety of aircraft and military systems since 1968. I have seen it all and it makes me sick. I have tried to change the system for a long time and have run up against a brick wall.
To; 747FOCAL
I'm gonna get shot for saying it here, but I was always told that 99.5% of all crashes were caused by pilot error.
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How come I read about so many crashes attributed to pilot error just like this recent egyptian 737 crash? It might have been a systems failure, but that Alaska flight 261 was pilot error and I don't see anybody sueing the dead pilots. 