An investigation of passenger exit selection decisions in aircraft evacuation situations

This paper presents results from a questionnaire study of participant exit awareness and suggested exit selection in the event of emergency evacuations involving narrow body aircraft. The study involved 459 participants with varying flight experience. The results of this study supports the hypothesis that poor understanding by passengers of aircraft exit location and configuration may be a contributory factor in the resulting poor exit selection decisions made by passengers in emergency situations. These results have important safety implications for airlines and also provide important insight to evacuation model developers regarding the decision making process in agent exit selection.

Investigating the impact of aircraft exit availability on egress time using computer simulation

This paper examines the influence of exit availability on evacuation time for narrow body aircraft under certification trial conditions using computer simulation. A narrow body aircraft which has previously passed the certification trial is used as the test configuration. While maintaining the certification requirement of 50% of the available exits, six different configurations are examined. These include the standard certification and five other exit configurations based on commonly occurring exit combinations found in accidents. These configurations are based on data derived from the AASK database and the evacuation simulations are performed using the airEXODUS evacuation software. The results show that the certification practise of using half of the available exits predominately down one side of the aircraft is neither statistically relevant nor challenging. For the aircraft cabin layout examined, the exit configuration used in certification trial produces the shortest egress times. Furthermore, three of the six exit combinations investigated result in predicted egress times in excess of 90 seconds, suggesting that the aircraft would not satisfy the certification requirement under these conditions.

Explicit finite volume modeling of aircraft anti-icing and de-icing

In this paper, a runback water and ice prediction model is extended to anti-icing and thermal de-icing situations. The resulting coupled equations that govern thin-film flow, ice accretion, and heat conduction in the multilayered system substrate-ice-water are solved using an explicit finite volume approach. The procedure is implemented in the three-dimensional icing code ICECREMO2, and both structured and unstructured grids can be considered. Numerical results are presented to compare the present code simulations to some data provided by other ice prediction codes and to show the capabilities of the present numerical tool.

Réflexions sur l'appauvrissement des syntaxons aux limites chorologiques des unités phytosociologiques supérieurs et quelques-unes de leurs consequences

Con la ayuda de algunos ejemplos, se estudia el comportamiento de los sintáxones en los límites corológicos de las unidades fitosociológicas superiores; se muestra que, a medida que nos alejamos de su centro de gravedad, esas unidades pierden poco a poco sus especies y que, en sus límites corológicos, no quedan más especies características de unidades superiores para definir las comunidades. Se evocan entonces algunas consecuencias de esas observaciones: noción de combinación específica original, interpretación fitosociológica de los sintáxones, nomenclatura fitosociológica.

Efficient Non-Linear Idealisations of Aircraft Fuselage Panels in Compression

Aircraft fuselages are complex assemblies of thousands of components and as a result simulation models are highly idealised. In the typical design process, a coarse FE model is used to determine loads within the structure. The size of the model and number of load cases necessitates that only linear static behaviour is considered. This paper reports on the development of a modelling approach to increase the accuracy of the global model, accounting for variations in stiffness due to non-linear structural behaviour. The strategy is based on representing a fuselage sub-section with a single non-linear element. Large portions of fuselage structure are represented by connecting these non-linear elements together to form a framework. The non-linear models are very efficient, reducing computational time significantly

Influence of Manufacturing Tolerance on Aircraft Direct Operating Cost (DOC)

The influence of manufacturing tolerance on direct operating cost (DOC) is extrapolated from an engine nacelle to be representative of an entire aircraft body. Initial manufacturing tolerance data was obtained from the shop floor at Bombardier Aerospace Shorts, Belfast while the corresponding costs were calculated according to various recurring elements such as basic labour and overtime labour, rework, concessions, and redeployment; along with the non-recurrent costs due to tooling and machinery, etc. The relation of tolerance to cost was modelled statistically so that the cost impact of tolerance change could be ascertained. It was shown that a relatively small relaxation in the assembly and fabrication tolerances of the wetted surfaces resulted in reduced costs of production that lowered aircraft DOC, as the incurred drag penalty was predicted and taken into account during the optimisation process.

Parametric optimisation of manufacturing tolerances at the aircraft surface

Up until now, aircraft surface smoothness requirements have been aerodynamically driven with tighter manufacturing tolerance to minimize drag, that is, the tighter the tolerance, the higher is the assembly cost in the process of manufacture. In the current status of commercial transport aircraft operation, it can be seen that the unit cost contributes to the aircraft direct operating cost considerably more than the contribution made by the cost of block fuel consumed for the mission profile. The need for a customer-driven design strategy to reduce direct operating cost by reducing aircraft cost through manufacturing tolerance relaxation at the wetted surface without unduly penalizing parasite drag is investigated. To investigate this, a preliminary study has been conducted at 11 key manufacturing features on the surface assembly of an isolated nacelle. In spite of differences in parts design and manufacture, the investigated areas associated with the assembly of nacelles are typical of generic patterns in the assembly of other components of aircraft. The study is to be followed up by similar studies extended to lifting surfaces and fuselage

Integrating Aircraft Cost Modelling into Conceptual Design

The article presents cost modeling results from the application of the Genetic-Causal cost modeling principle. Industrial results from redesign are also presented to verify the opportunity for early concept cost optimization by using Genetic-Causal cost drivers to guide the conceptual design process for structural assemblies. The acquisition cost is considered through the modeling of the recurring unit cost and non-recurring design cost. The operational cost is modeled relative to acquisition cost and fuel burn for predominately metal or composites designs. The main contribution of this study is the application of the Genetic-Causal principle to the modeling of cost, helping to understand how conceptual design parameters impact on cost, and linking that to customer requirements and life cycle cost.