ABSTRACT
The safe use of aircrafts, i.e. air liners can be assured as a result of the high-level maintenance by permanently maintaining the suitability for air lines. The Part 145 of EC decree No.EASA 1321/2014 EK requires the appropriate training of competent persons in the scope of knowledge concerning human elements and human mistakes.
The importance of the human element shows that accidents and air line events taken place for human mistakes and for technical reason is 4 to 1.Analyzing reasons a significant risk can be caused by the unsatisfactorypreparedness of employees for the professional operation of technique, their superficial knowledge of the complete lack of such knowledge,as well as such events can take place, because they do not know
the function of an apparatus, they have no behavior sample and their contact system is also imperfect,
transmission of information is jammed because of wrong solutions for organization.Anyway, maintenance mistake do not only mean mistakes causing a certain event, but also mistakes caused by reasons to be led back to competent persons, as well as workstation, organizational and environmental effects.
Key words: human element, air liners’ maintenance
1.INTRODUCTION
‘‘Errare humanum est’’
(Cicero)
Despite the fact that the aircraft is one of the today’s most secure vehicle (during one million kilometers of air line fewer accident demanding mortal victims occurs than in motorways) the public opinion adjudges it dangerous, because [1]:
•passengers can not avoid risks and are aware of defenseless;
•due to the activity of press a piece of news about an accident or an extraordinary event immediately gets known in the whole world;
•almost everyone can lose their life on the occasion of an airflying accident.
The safe use of aircrafts, i.e. airliners can be assured by permanentlymaintaining their suitability for air lines. One of the most important step of this process is the systematic and high-level maintenance of aircrafts.
The suitability for air lines is the ability of the aircraft – determined mainly in technical requirements –promoting the safe carrying out of a flight.This generally permanent suitability can be maintained with earth service and maintenance. It is obvious that from among the conventional maintenance and operations methods the operation system functioning until the occurrence of the first mistake can not be absolutely used and the
maintenance based on a rigid cycle can only partially be used for assuring the suitability for flights.It is a fact supported by statistical data that cyclic maintenance results neither the appropriate efficiency nor the appropriate security [2]. The maintenance based on technical diagnostics – which may be perhaps used for assuring the suitability for flights – does not take into account human elements and concentrates on to technical problems.
Inside the European Union technical requirements concerning the maintenance of aircrafts are determined by the EASA established under the EP and EC decrees No1592/2002/EC of 15th of July 2002.
Our article draws our attention to the importance of human elements on the basis of prescriptions of EASA.
2.REQUIREMENTS OF THE PRESCIRPTION OF EASAPART145CONCERNING HUMAN ELEMENTS
The EASA directs and supervises the activity of organizations maintaining aircrafts assuring the permanent suitability for flights by carrying out service and basic maintenance according to the dispositions of Part145of the1321/2014 EC decreeof 20th of November 2003. Thus the aircraft maintaining organization establishes and verifies the preparedness of employees taking part in maintenance, control and/or quality management audits in according to the method and dispositions approved by the competent air transportation authority. Beside the expertise necessary for this sphere of activity shall also include the importance of human element and efficiency necessary for appropriate comprehension of the role of the given person played in the organization.
Here shall be noted that such raise of the value of human element is a characteristic of quality management systems, from among which this can especially observed in the Total Quality Management. Beside the real capacity and ability of the co-worker of the organization the TQM can be established on the basis of human elements, authorization, confidence, permanent development, dependence of co-workers on each otherand team activity despite that the reality can be often characterized by standardized and dismembered routine work and incorporated verification mechanism and the team, as well as incorporated verification mechanismsand the verification and disciplining role of the team is dominant.
TheEASA Part145description requires that persons carrying out the maintenance of aircrafts (not only aircraft mechanics having professional service authorization) are obligatory to take part basicandrepeating coursesengaged in human elements. These courses present knowledge concerning human elements and mistake made by humans on the bass of practical examples in connection with the processes of the maintenance of aircrafts.
The term and content of the basic course are adjusted to the assignment (sphere of activity) of the concerned staff, while the repeating course trends to the update of knowledge concerning human elements and analyze of mistake made by humans taken place during the maintenance of aircrafts. The basic course shall be given after the joining the aircraft maintaining organization having the authorization according to EASA Part
145 within the first six months, while the repeating course shall be given at least once within two years after the basic course.
The basic course trends to the presentation of knowledge to be ranked to the following matters:
•presentation of human elements;
•effect of the culture of security / organizational factors;
•effects of human mistakes and other mistakes;
•human ability and its limits;
•role of the working environment;
•methods, information, tools and practice used in the maintenance of aircrafts;
•importance of communication;
•importance of teamwork;
•professionalism and reliability;
•function disorders to be led back to human elements within the given maintainingorganization.
If we examine this enumeration, we can easily find connection between the EASA Part prescription and 6 sigma1. In none of quality management tendency such a comprehensive and profound training activity can be established, like in 6 sigma, where all co-workers of the company is given any training for making as few as mistake possible. Meanwhile the main objective of 6 sigma includes the manufacturing, service providing in high quantity without mistakes, resp. mistakes within the technical tolerance level.For avoiding this objective this method uses by all manner the maintenance of regularity and assurance of ability (machine, process, measuring instrument) as a tool. Naturally the above-mention TQM principles are also mentioned in 6 sigma with the MSZ (Hungarian Standard) EN ISO 9001:2001(e.g.. customer in the centre, management is responsible, involvement of co-workers etc..) and therefore we can regard the 6 sigma program one of the possible ways to the TQM. The question arises if there is any quality correction based statisticevaluation in processes characterized not by mass-like feature but more an individual service providing activity. It is explained in the quality approach of P.B.Crosby [13] whose quality view is that the quality is determined by the activity of the leader and this does not mean any more than the meeting the requirements.This means that theEASAPart145 prescription summarized just these requirements concerning human elements and its objective is the decrease of mistakes made during the maintenance under the acceptable risk level.
The training philosophy according toEASAPart145emphasizes in the subject of security culture that there is neither absolute security and 0 mistake,while
1In mathematical statistics ‘sigma’ means spreading.The6sigma method endeavors to decrease spreading as a tool of process correction.Namely:sigma is used for measuring the performance of the process in Aspect of reaching an mistakeless result.Mistake means all things causing the customers’ unsatisfaction, e.g. product not meeting customers§’ requirements, a service of low quality or the high price.
The objective of the quality view of P.B.Crosby is to achieve 0 mistake. Since then it has cleared up and has already been proved in many places that there are only 2 to 3 airflying accidents demanding human victims in comparison to one million flights in our time (this means a compliance of99,999997% and approaches the quality requirement of 6 sigma). The goal is to decrease this number by an order of size within the following 10 years (0.2 to 0.3 npmo/ppm2in this case this index number significantly exceeds the 5 sigma quality value.
3.WHY IS IMPORTANT THE KNOWLEDGE OF HUMAN ELEMENTS?
According to the well.-known establishment of Cicero: „To err is human”. The ability to err is the ability of all human beings and can not be completely eliminated. Like all of us, the best qualified persons can also make unexpected mistakes, perhaps dozens of them a day.Therefore can be often heard:„Everyone has the right to err and no one is perfect.”Here can not be avoided that sometimes a smaller mistake occurs during the preparation or effectuation.However, it does not come to the same thing, what kind of mistake has occurred and what consequences thismistake had. In air transportation no mistake is allowed, because they can also lead to disasters.The expression “intolerable” does not exclude the occurrence of such mistakes.
The maintenance of aircrafts significantly changed in the course of years.Recent aircrafts contain materials, driving mechanisms and electronic subsystems, which did not use to exist in previous types.Therefore the work of airplane mechanics is getting more and more complicated and exhausting.
However, the use of new materials and electronic systems does not go with the decrease work load and the level of required professional knowledge of airplane mechanics and inspectors co-operating the maintenance of aircrafts, because the most of maintenance works get on being carried out with human co-operation and in many cases under working circumstances not proposed by ergonomics (Fig. 1.
).
Fig.1The maintenance of the fuselage while ago and today, but always in a special body position
2The number of in appropriateness in comparison to one million mistake possibilities, i.e. millionth part.
The idea ofhuman elementbegan to spread when in the field of commercial air transportation was recognized that the numbers of airflying accidents caused by human mistakessignificantly exceeds the number of airflying accidents caused by technical mistakes.
Fig.2 Change of causes of airflying accidents from the “beginnings” until our days [3]
This changed is shown in Fig.2 that in our time the proportion of accidents caused by technical mistakes is only 20 percent in contradiction of 80 percent caused by humans (pilots, aerial guiders, airplane mechanics etc.).
During the maintenance of aircrafts mistakes can also occur, but it does not come to the same thing, how aftermistakes occur and how serious they are. According to current statistic data 6% of accidents caused by human mistakes are caused by mistakeoccurred during the maintenance, while such mistakes take part in 12 to 15 percents of cases in the development of accidents [4]. This value around 20% is the serious risk of the maintenance. Theknowledge of riskis basically important, because it refers to the incertitude of the results of the maintenance.It is obvious that the chances of the successfulness of the maintenance shall be increased so that mistakes caused by the maintenance – like risk factors – decrease. This is only possible in such a manner that the maintenance is not only taken into account as a technical problem and its risk, but also completing the technical problem human elements as risk factors. Therefore is important the comprehension of the nature of human mistakes.
4.IDEA OF HUMAN ELEMENT
According to the EASA Part 145 prescription [14]:„Human element means all factors relating to aeromechanic planning, certification, professional training, operation and maintenance and endeavor make connections between human elements and other system components taking the human capacity into account 3.” Human elements are expressed in the following mutual effects:
•human and technique;
•humans and prescription;
•human and environment;
•human and human.
If we think in a system theory framework and regard the maintenance of aircrafts a uniform system, all elements of them will be in close connection with each other and characteristics of these connections can be understood by taking these connections into account [2].Within this system four subsystems can be separated on the basis of the CAP 715[5](CivilAviationPublications) (Fig.3), but we can safely add the 5th(m) subsystem indicating the role of the committed management.
Fig.3Original model and model completed with the management
Components of the SHEL model
S. software containing maintenance procedures and manuals, schedule of the maintenance as well as any other written and unwritten rules;
H. hardware containing the aircrafts, tools, repairing materials, components etc;
E. environment including the hangar, conditions of the transportation maintenance, structure of the management, control structure etc. (Environment);
L. the fourth element of the system is the humanhimself with his own physical, psychic and psychophysics characteristics (Lifeware), who is position in the centre of the model and is in contact with other people (Lifeware);
3The human ability includes all abilities and limits having influence to the security and efficiency of air transportation.
m. means the quality committed management. (The Japan Navy is separately engaged in the role of the management (under the name m-SHEL)in the course of the evaluation of the cooperation between systems and operators [17.])
From theSHELmodel it follows that the examination of the human and his environment does not only mean the physical environmental factors surrounding the co-worker (in this case the airplanemechanic), but also tools and materials used for working, as well as working practice and the workorganization both in the case of individual and team work. Anyway in the course of the weighing the risk of mistakes, we shall established the requirements which the co-worker having the given the sphere of activity (assignment) shall meet and how he meets this requirements [15]. All these are in connection with the human himself: his abilities, possibilities and limits.
On the basis of the theory of Reason [6]- advanced by Scott etal [7]–the abovereciprocal effects can be illustrated by means of the Swiss cheese example(Fig.4).According to the Swiss cheese theory eyes correspond to active mistakes. Any airflying accident or other event can take place, if these mistakes jus concede with each other, resp. Enhance each other.
Fig.4Swiss cheese model
The main objective of theEASA Part 145prescription is enable persons taking part in the maintenance of aircrafts to meet requirements set up by the technical background, maintaining organizationand aircraft. This methodendeavors to realize such a forming of consciousness enabling humans to recognize their personal responsibility for perfect operation of the system concerning the technique, organization and result of operation.In the course of two-way compliance maintaining companies shall make a technical background and organization adjusting possible behaviors of people and reckoning with the possible changes of their behavior. If on “any slice of the cheese” (Fig.4) can be achieved that the number and size of eyes is as low as possible, the defense will prevent the occurrence of the airflying event.
It is worth developing the strategy of the maintenance of the aircraft in the knowledge of that a human can err at any time, since his attitude can unconsciously and automatically take place.It can not be excluded that on the basis of the principle to err is human such mistake take place, which the co-worker can cause due to his attitude not accommodating to concrete conditions.
In the reality the human declare bankrupt in dangerous situations, because he is not prepared to handle these situations.Therefore co-workers shall be trained to make countermoves for avoiding these mistakes and this knowledge shall be updates [8].
In the four-factor system(human, technique, prescriptions, environment) the human can meet the other three requirements, if he can recognizeerrors of his attitude occurred before and accommodates to concrete requirements and conditions.
In the four-factor system mentioned conflicts can develop between human and technique;human and prescriptions;human and results of work; finally between human and human as well. Machines, apparatuses and other material conditions often render more difficult the safe working and in many cases exclude it.
Disorder sources can drive from the not appropriate preparedness of co-workers for professionally operating the technique and they from that they have no attitude samples necessary for this.Not appropriate solution also render more difficult to develop safe, professional and in ergonomic view unbeatable attitude conditions based on the quality. It is also possible that the co-worker has not learned the appropriate attitude forms corresponding to the organization and therefore they are hit by unwanted effects.
The superficial knowledge of airplane mechanics can lead to a conflict, if he e.g. does not know the function of an apparatus and its possible danger sources etc. Conflicts between human can derive from the imperfect system of connections, the information flow works by fits and starts between levels of the supervision subordinates to each other.
Disorders sources mentioned before spoil the quality and prevent the improvement of productivity and quality. Therefore one of the main objectives of measures to be taken for renewing the maintenance is to minimize conflicts.According to experiences operating troubles and accidents cause more serious cost effects than measures connected to their analysis and prevention.
An important aspect is that persons taking part in the maintenance of aircrafts know dangers occurring during the maintenance. These possible dangers shall be presented to co-workers possibly on the basis of cases taken place before.The attention shall be drawn to mistakes which may occur and their consequences.