Browsing by Author "Snow, John"

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    Aviation maintenance in multicultural settings : the challenges of cultural tolerance and of employees' maintenance resource management/human factors (MRM/HF) awareness
    (Cranfield University, 2001-10) Al-Harabi, Ali; Snow, John; Muir, Helen
    This thesis deals with two major issues, the first is the multicultural nature of many Aircraft Maintenance Technicians (AMTs) teams and the way in which cross-cultural communication and/or barriers to communication might affect teams' performance; and the second is the practice of Maintenance Resource Management/Human Factors (MRM/HF) in developing countries. Using the questionnaire method, this research examines the opinions of AMTs and maintenance supervisors from eight maintenance organisations regarding their attitudes to colleagues from other nations and cultures, and how this might affect their performance in the workplace. It also seeks to probe the respondents' attitudes to, for example, stress, responsibility, attitude to authority and handling conflict, considering these opinions alongside the national and cultural backgrounds of the participants. In order to do this, the respondents themselves were organised into different "culture groups" with the national characteristics of the groups being defined according to Hofstede's ideas of individualistic and collectivistic societies. The thesis begins from the premise that most AMTs demonstrate greater individualistic tendencies than airline pilots, and while their individualism may be partly traceable to the signatory authority of A&P, other factors, such as education, training and working/ socialising with Westerners, are also important influences. This study aims to show that a large contingent of AMTs and maintenance supervisors from collectivistic cultures share many of the attitudes and work goals of individualists. For example, this study will show that AMTs and maintenance supervisors from most collectivistic cultures lean towards a preference for a command style that is closer to the egalitarian pole than to the hierarchical one; tend to reject the idea of blind obedience to supervisors; tend to believe that technical merit, not social status or good connections, makes for successful managers; lean towards the acceptance of only a modicum of rules to deal with the issue of uncertainty in the workplace; tend to favour work goals that pertain to their personal needs and career aspirations, etc. The study also sheds light on AMTs and maintenance supervisors' belief systems, inter-ethnic stereotypes and feuds in the workplace, and on that basis, constructs profiles of the eight aviation maintenance organisations previously mentioned. This also addresses the question of whether these companies have met the cultural diversity and MRMawareness challenges. The analysis specifically provides answers to the fundamental questions of this study, such as whether AMTs and maintenance supervisors from some collectivistic cultural groups do, in fact, have attitudes and work goals that are similar to those of AMTs and maintenance supervisors from individualistic cultural groups; whether ANITs, as a professional group, are actually more individualistic than are airline pilots from the same countries in attitudes and work goals; to what extent ANITs' work-related attitudes and values are universal, or are influenced by their national cultures; whether placing AMTs from different national cultures in the same work teams has deleterious effects on the functioning of an aviation organisation; whether multicultural teams face insurmountable problems as functioning units because of stereotypes, discrimination, and other ills; whether the management of aviation maintenance organisations has been meeting the challenges of cultural diversity effectively, i. e. whether management has minimised cultural diversity as a potential performance barrier, and has, instead, begun to mine value-added potential of cultural diversity; and whether aviation maintenance organisations have met the NIRM-awareness challenge.
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    Bayesian model for strategic level risk assessment in continuing airthworthiness of air transport
    (Cranfield University, 2010) Jayakody-Arachchige, Dhanapala; Place, Simon; Snow, John
    Continuing airworthiness (CAW) of aircraft is an essential pre-requisite for the safe operation of air transport. Human errors that occur in CAW organizations and processes could undermine the airworthiness and constitute a risk to flight safety. This thesis reports on a generic Bayesian model that has been designed to assess and quantify this risk. The model removes the vagueness inherent in the subjective methods of assessment of risk and its qualitative expression. Instead, relying on a transparent, structured mathematical process based on Bayes’ Theorem of conditional probabilities, the model yields a quantitative risk output expressed as a probability of error coupled with a probability of consequence based on data. The Bayesian model has 184 nodes and 1138 parameters that define causal factors for error against which data is collected as either beliefs or evidence, the latter returning more reliable results. Beliefs could be gradually replaced with evidence as they become available, improving fidelity. The generic model can be modified by adding or truncating parameters to suit conditions applicable to specific organizations or similar groups. The model was validated using field data from a cargo operator using large western jet freighters, covering 34,338 sectors of which 193 carried human error. Separate tests were performed simulating the operator’s belief that it was operating to global standards. The output for belief was consistent with global and UK flat rate safety levels, achievable if the operator flew 3M and 6M sectors respectively according to their belief. However, the output from evidence returned a risk level more severe than the belief, partly driven by the allowance for unknowns built into the computing technique and part by the relatively small number of sectors considered. In “what-if” prediction mode the model calculates the change in risk level due to new errors, and through sensitivity analysis it can identify and rank performance indicators. In CAW organizations subjected to Risk Based Oversight (RBO) concept and ICAO mandate on Safety Management System (SMS), the model can set risk threshold levels for individual organizations, to measure variations, and by continuous updating, to monitor safety performance at strategic level. Sharing data and with agreed performance levels, the Regulator and operators should be able negotiate an oversight plan. Using the model pro-actively, the organization could exercise a degree of self-regulation, thereby accruing cost benefits through reduced Regulator oversights.
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    Development of a simulation approach to the management of aircraft rotable spare parts
    (Cranfield University, 1997-06) Al-Anezi, M.; Snow, John
    A simulation model has been developed for the effective management of aircraft rotable spare parts. The model was based on real data obtained from airlines representing various processes and functions of the airlines maintenance operations. The main processes that were thoroughly discussed were failure and repair turnaround time representing the demand and supply of spare parts systems. Results of the simulation model have been compared to those of the standard method for the objective of establishing a level of confidence of results of the simulation model, and that helped to enhance the understanding of service level, and the assumptions behind the standard method. The developed model is more realistic with regard to estimating requirements of aircraft rotable spare parts, and have the advantage of being able to consider important management policies that were not considered in the standard method.
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    Effect of in-service aircraft mission variation on airline fleet management
    (Cranfield University, 1996-04) Chen, Han Hua; Taylor, A. Frank; Snow, John
    The air transport markets affected by global economic climate and regional demand characteristics are evolving fairly dynamically. To cope with the evolving demand and to penetrate desired market segments, operators' usage of aircraft has been getting more and more dynamic with increased deviation from the originally designed mission objectives. The objective of this research is to investigate the effects of in-service rrusslon variation on aircraft structural performance so as to provide airlines with a more realistic approach toward better fleet management. During the research, the scenarios and phenomena causing fleet in-service mission variations were investigated. A survey on the utilisation of world-wide aircraft fleets was conducted and presented. The in-service missions of aircraft fleets were found to vary significantly in terms of mission profile. Furthermore, the utilisation patterns of individual aircraft in the same fleet of a major airline are also being thoroughly analysed. Tremendous variations of mission mixes are found among individual aircraft. In order to analyse the effects of the in-service mission variation, methodologies and models based on fatigue test results have been developed by the author. Actual service data are being input for the effect analysis. It is found that the mission variation has a considerable engineering influence on the aircraft's structural performance either in terms of mission airworthiness or fatigue life span. Finally, a conceptual model, the 'Integrated Airline Fleet Management Model' (IAFM), has been developed as a blueprint for practical application. By implementing the IAFM, airline will be able to obtain a realistic picture of the health of its aircraft. With a more reliable basis for maintenance planning, improved inspection accuracy, reduced maintenance cost and better structural airworthiness can be achieved.
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    Evaluating and improving worldwide implementation of future air navigation systems
    (Cranfield University, 2001-03) Whelan, Conor; Snow, John
    Air traffic congestion problems in many areas of the world are well known and have been highly publicised in recent years. This airspace dilemma, which results in delays and other undesirable knock-on effects, is escalating at a phenomenal rate and requires immediate attention. Correspondingly, there is concern about safety standards in some worldwide airspace regions. In addition, it is imperative that the significant projected growth in air transport movements over the next two decades is accommodated. Thus. there is an urgent need to solve the current airspace problems and plan in a responsible manner to meet forecast demand. Solutions to these predicaments have been developed and are encompassed Linder the auspices of the term. 'future air navigation systems'. The systems include technolo-gies and procedures that merge to optimise the potential of airport and airspace resources so that the capacity. flexibility and safety of these resources are maxiinised. while delays and their operating costs are ininimised. Future air navigation systems use automated communications. navigation and surveillance technologies to provide enhanced air traffic management through continuous information on aircraft positions and intention', so that reductions in separation are possible without compromising safety. However. confusion exists rei-, arding vdiat technologies and procedures COIlStitLItC t1leSC futiire air navigation systems. Additionally. their current worldwide integratioil staILIS IS not as advanc d as it should be and. in fact. remains larljwlý' Unknown. Indeed. their successful introduction is far from guaranteed at present. Therefore. tills research addresses these requirements by evaluating and improving implementation of tile systems on a global basis. Ultimately. this thesis provides a comprehensive analysis that discovers what systems are pertinent and whether or \, \-here they have been applied to date, in addition to developino and validatin- a framework strategy for improved introduction of the future air navigation systems around the world.
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    The feasibility of maintaining regional airline access to congested European airports
    (Cranfield University, 1997-05) Jefferson, Andy; Golding, R.; Snow, John
    At present runway congestion in the airline industry has reached a dangerously high level. The effects of this are very costly to all parties involved; US$5bn per year in Europe in 1989 alone. The problem demands urgent attention to accommodate the expected average growth in air transport of 6% per annum. up to the year 2000. It is becoming more and more obvious, however, that the construction of new runways is not a feasible option due to both political, environmental and physical space limitations within Europe. Alternative solutions are therefore required In 1991 the European Regional Airlines Association, (ERA), produced a document entitled, "I"he Vital Link', which outlined a number of ways in which regional aircraft could use there performance differences from the larger jet aircraft to help generate extra runway capacity from existing runways. Whilst the author was a member of the ERA operations committee he developed some of these ideas further. It is the objective of this thesis to examine the ideas developed by the author from both a theoretical and practical point of view to determine the feasibility of implementing them at congestedE uropeana irports. T'heoretical simulation modelling of Manchester, Zurich and Gatwick airports was undertaken using the FAA SIMMOD airport and airspace simulation model. This produced delay time savings and changes to peak hour movement rates which were used in a cost benefit analysis model to see whether or not the procedure would make a cost saving. The practical side of the thesis focusedo n an industry questionnairet o regional airlines, major airlines and airports to obtain their views on the new proceduresa nd cases tudieso f the proceduresa t Manchestera nd Gatwick airports. Results of the work show that whilst the procedures can effectively reduce operating delays they have a lessor impact on peak hour movement rates. Optimum use of the procedures is unique to individual airports and depends on the runway operation mode, TMA airspace configuration and the type and variability of the traffic mix. Actual application of the proceduresw ill be dependanot n political and environmental restrictionsa nd likely future changesin regional airlines aircraft fleets.