Accidents, probable causative

Prepare a summary report include a discussion of the events prior to the accident, a description of the accident, probable causes, and actions to be taken to prevent a recurrence. 

The probable cause of the accident was overfilling due to level indicator failure. Water removal from carbon dioxide was not always sufficient to assure good pressure and level readings in the tanks. Residual water could cause meters to fail from ice formation. 

In general, tlie carriage of hazardous materials does not appear to be a significant cause of, or aggravating factor in, aircraft accidents. However, improperly packed and loaded nitric acid was declared tlie probable cause of a cargo jet crash at Boston in 1973, in which tliree crewmen died,"... 

Such an accident happened on an larger scale involving 83 kg of the mixture. There was a very substantial fire that was probably caused by trimethylamine self-ignition. 

The probable causes of this accident include (1) use of nonwelded pipe, (2) installation of pipe in trenches, resulting in an accumulation of flammable vapors, and (3) lack of automated vapor detection analyzers and alarms. 

Probable causes of this accident include (1) installation of a fail-open valve instead of a fail-closed valve, (2) lack of vapor detectors, (3) lack of a block installed as a mitigating device, and (4) failure to eliminate ignition sources in this operating region. 

The National Transportation Safety Board (NTSB) has found much evidence to indicate the probable cause of the January 6, 2005, collision and derailment of Norfolk Southern train 192 in Graniteville, South Carolina, was the failure of the crew of Norfolk Southern train P22 to return the main line switch to the normal position after the crew completed work at an industry track. Contributing to the severity of the accident was the puncture of the ninth car in the train, a tank car containing chlorine, which resulted in the release of poison gas. 

The effects of chronic hypertension on the human organism are, with one exception, of little interest to the investigator studying pathogenesis, although of great import to the sufferer and his physician. That exception is failure of the kidneys. Disease and failure of the heart are probably caused by chronic overstrain, often associated with another metabolic disease, arteriosclerosis of the coronary arteries. They account for about two thirds of the deaths primarily due to hypertension. Strokes of apoplexy, or cerebral vascular accidents, from rupture or thrombosis of a cerebral artery weakened by disease cause another sixth, uremia about one twelfth, and other conditions the remainder (28). Except for uremia, these events are usually the result of overwork and increased arterial tension. Only rarely does the heart escape hypertrophy. 

The results of sleep deprivation have been linked to motor vehicle accidents, major industrial accidents such as the Exxon Valdez, and Three Mile Island, and the Space Shuttle Challenger disaster (2). The U.S. National Highway Traffic Safety Administration (NHTSA) in 1999 estimated that 56,000 police-reported crashes and 4% of all traffic crash fatalities (1550 cases) involved drowsiness and fatigue as principal causes (3). Sleepiness was a probable cause in about one third of all fatal-to-driver motor vehicle accidents involving commercial truck drivers (4). 

In 1990, the National Transportation Safety Board (NTSB) completed a study of 182 fatal-to-the-driver truck accidents to investigate the probable cause of the accidents. While the study was designed under the assumption that most fatal heavy truck crashes may be related to alcohol and other drugs, it was found that the most frequently determined probable cause was fatigue (12). A 1993 analysis of the Fatal Accident Report System (FARS) also suggested that truck driver fatigue is a contributing factor in about 30% of heavy truck accidents. 

As an initial step, the reports of l80 in-process accidents were viewed. A sianmary of the type of information obtained is shown in Fig 22. The process operation and the probable causative stimuli which led to the accident are given in terms of the number of accidents and the percentage of the total number. Thus the most probable causes of an accident were identified in an accident analysis. The causes varied by process operation and material type. However friction, impact, electrostatic discharge (ESD), and heating were the most commonly identified causative stimuli. 

Figure 22. Probable causative stimuli for accidents occurring in specific process...

The NTSB determines that the probable cause of this accident was the failure of the flight crew to adequately manage the airplane s fuel load, and their failure to communicate an emergency fuel situation to air traffic control before fuel exhaustion occurred. (OTSB 1991, p. 76, emphasis added)... 

Note These criteria are based on failure probability (not accident probability). The accident/risk-based criteria (e.g. from Def Stan 00-56 or MIL-STD-882) consider die probability of the consequence (i.e. the accident) of various types of hazards. It is in this aspect that the accident/risk-based approach is difficult to apply, because a system target can only be set after an accident risk is defined and the accident sequence is fully populated with the probability of each contributing cause/event. For more information, see Kritzinger (2005), Chapters 4 and 5. When considering the use of risk (i.e. die product of accident probability and accident severity), please do ke in mind ... 

GM21.A.3B(d)(4) para 3,7 For large commuter transport aircraft, history has shown that the accident probability due to all technical causes is 1 in lOmiUion flying hours (i.e. lE-7 per flight hour). 

Probit functions were evaluated as the most often used tools for determining the effects of major accidents, probably due to the fact that these functions are included in the EFFECTS software. Furthermore, it was determined that the values of the limits of acute toxicity are not always the same when applying different methods. For example the value of IDLH for chlorine differs in order of tens. The ERPG has the lowest difference in the values in the order of units. This can be caused by the absence of literature sources. 

In the period between 1980 and 1993 no accidents were reported in which a GPS or global positioning system was mentioned in either the factual or probable cause report. The analysis of the accident reports between 1993 and 2007 showed that, in 29 cases, it could be inferred that the accident was related to the utilization of... 

In two reports (NTSB report LAX01FA055 and SEA01LA138) it was mentioned in the probable cause statement that GPS was a factor in the accident. In all other cases, the narrative text had to be used to identify the use and the problem with the use of the GPS. 

As noted earlier, an accident investigation is not complete until a report is prepared and submitted to the proper authorities. Special report forms are available in many cases. Other instances may require a more extended report. Such reports are often very elaborate and may include a cover page, a title page, an abstract, a table of contents, a commentary or narrative portion, a discussion of probable causes, and a section on conclusions and recommendations. The following outline has been found especially useful in developing the information to be included in the formal report ... 

Explain probable cause of accident giving reasons. 

Fig. H/3.2.5 1 is an important record-keeping document for HAZID analysis. This hazard register is same as the risk register discussed in Clause 3.2 of Chapter I, and details of the risk register are shown in Fig. 1/3.2.1-1. Since details of the risk register are already available, it will not be repeated here. Fig. 11/3.2.5-1 shows the basic structure. In the case of HAZID, hazard register is the popular term, hence it is used here. These hazard registers are available for each section of the facility. For each section, all hazards and major incidents/accidents are listed along with the probable cause. The register also contains the control measure, assumptions, etc. This will become the main document for subsequent use.

Where plugs and sockets are used for portable tools, sufficient sockets must be provided for all the equipment and adaptors should not be used. Many accidents are caused by faulty flexible cables, extension leads, plugs and sockets, particularly when these items become damp or worn. Accidents often occur when contact is made with some part of the tool which has become live (probably at mains voltage), while the user is standing on, or in contact with, an earthed conducting surface. If the electrical supply is at more than 50 volts ac, then the electric shock that a person may receive from such defective equipment is potentially lethal. In adverse environmental conditions, such as humid or damp atmospheres, even lower voltages can be dangerous. Portable electrical equipment should not be used in flammable atmospheres if it can be avoided and it must also comply with any standard relevant to the particular environment. Air operated equipment should also be used as an alternative whenever it is practical. 

The NTSB investigators determined that the accident s probable cause was the captain s inappropriate response to the activation of the stick shaker, which led to an aerodynamic stall from which the airplane did not recover. 

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