The airEXODUS evacuation model and its application to aircraft safety

Computer based mathematical models describing the aircraft evacuation process have a vital role to play in the design and development of safer aircraft, the implementation of safer and more rigorous certification criteria, in cabin crew training and post-mortem accident investigation. As the risk of personal injury and the costs involved in performing full-scale certification trials are high, the development and use of these evacuation modelling tools are essential. Furthermore, evacuation models provide insight into the evacuation process that is impossible to derive from a single certification trial. The airEXODUS evacuation model has been under development since 1989 with support from the UK CAA and the aviation industry. In addition to describing the capabilities of the airEXODUS evacuation model, this paper describes the findings of a recent CAA project aimed at investigating model accuracy in predicting past certification trials. Furthermore, airEXODUS is used to examine issues related to the Blended Wing Body (BWB) and Very Large Transport Aircraft (VLTA). These radical new aircraft concepts pose considerable challenges to designers, operators and certification authorities. BWB concepts involving one or two decks with possibly four or more aisles offer even greater challenges. Can the largest exits currently available cope with passenger flow arising from four or five aisles? Do we need to consider new concepts in exit design? Should the main aisle be made wider to accommodate more passengers? In this paper we discuss various issues evacuation related issues associated VLTA and BWB aircraft and demonstrate how computer based evacuation models can be used to investigage these issues through examination of aisle/exit configurations for BWB cabin layouts.

The AASK Database V3.0: a database of human experience during aircraft evacuation incidents

This paper describes recent developments with the Aircraft Accident Statistics and Knowledge (AASK) database. The AASK database is a repository of survivor accounts from aviation accidents developed by the Fire Safety Engineering Group of the University of Greenwich with support from the UK CAA. Its main purpose is to store observational and anecdotal data from the actual interviews of the occupants involved in aircraft accidents. Access to the latest version of the database (AASK V3.0) is available over the Internet. AASK consists of information derived from both passenger and cabin crew interviews, information concerning fatalities and basic accident details. Also provided with AASK is the Seat Plan Viewer that graphically displays the starting locations of all the passengers - both survivors and fatalities - as well as the exits used by the survivors. Data entered into the AASK database is extracted from the transcripts supplied by the National Transportation Safety Board in the US and the Air Accident Investigation Branch in the UK. The quality and quantity of the data was very variable ranging from short summary reports of the accidents to boxes of individual accounts from passengers, crew and investigators. Data imported into AASK V3.0 includes information from 55 accidents and individual accounts from 1295 passengers and 110 crew.

[Recording review] William Herschel, Symphonies Nos. 2, 8, 12, 13, 14, 17

Tony Mann provides a review of the recording: William Herschel, Symphonies Nos. 2, 8, 12, 13, 14, 17, soloists, London Mozart Players / Matthias Bamert, Chandos 10048, 2003, (68 mins). [CD]

Examining the effect of exit separation on aircraft evacuation performance using evacuation modelling techniques: "Is the 60 foot rule relevant?"

This paper examines the influence of exit separation, exit availability and seating configuration on aircraft evacuation efficiency and evacuation time. The purpose of this analysis is to explore how these parameters influence the 60 foot exit separation requirement found in aircraft certification rules. The analysis makes use of the airEXODUS evacuation model and is based on a typical wide-body aircraft cabin section involving two pairs of Type-A exits located at either end of the section with a maximum permissible loading of 220 passengers located between the exits. The analysis reveals that there is a complex relationship between exit separation and evacuation efficiency. Indeed, other factors such as exit flow rate and exit availability are shown to exert a strong influence on critical exit separations. A main finding of this work is that for the cabin section examined under certification conditions, exit separations up to 170 feet will result in approximately constant total evacuation times and average personal evacuation times. This practical exit separation threshold is decreased to 114 feet if another combination of exits is selected. While other factors must also be considered when determining maximum allowable exit separations, these results suggest it is not possible to mandate a maximum exit separation without taking into consideration exit type, exit availability and aircraft configuration. This has implications when determining maximum allowable exit separations for wide and narrow body aircraft. It is also relevant when considering the maximum allowable separation between different exit types on a given aircraft configuration.

Report on the Testing and Systematic Evaluation of the airEXODUS Aircraft Evacuation Model

This report covers the testing and evaluation of the airEXODUS evacuation model. airEXODUS has been developed for evacuation certification testing, crew training and aircraft design. The report demonstrates the effectiveness of the model.

The use of computer simulation for aircraft evacuation certification: a report from the VERRES project

In this paper a methodology for the application of computer simulation to the evacuation certification of aircraft is suggested. The methodology suggested here involves the use of computer simulation, historic certification data, component testing and full-scale certification trials. The proposed methodology sets out a protocol for how computer simulation should be undertaken in a certification environment and draws on experience from both the marine and building industries. Along with the suggested protocol, a phased introduction of computer models to certification is suggested. Given the sceptical nature of the aviation community regarding any certification methodology change in general, this would involve as a first step the use of computer simulation in conjunction with full-scale testing. The computer model would be used to reproduce a probability distribution of likely aircraft performance under current certification conditions and in addition, several other more challenging scenarios could be developed. The combination of full-scale trial, computer simulation (and if necessary component testing) would provide better insight into the actual performance capabilities of the aircraft by generating a performance probability distribution or performance envelope rather than a single datum. Once further confidence in the technique is established, the second step would only involve computer simulation and component testing. This would only be contemplated after sufficient experience and confidence in the use of computer models have been developed. The third step in the adoption of computer simulation for certification would involve the introduction of several scenarios based on for example exit availability instructed by accident analysis. The final step would be the introduction of more realistic accident scenarios into the certification process. This would require the continued development of aircraft evacuation modelling technology to include additional behavioural features common in real accident scenarios.

Simulating the interaction of cabin crew with passengers during aircraft emergency evacuation conditions

In this paper we briefly describe new modelling capabilities within the airEXODUS evacuation model. These new capabilities involve the explicit ability to simulate the interaction of crew with passengers in managing evacuation situations

Simulating the Swissair flight 111 in-flight fire using the CFD fire simulation software SMARTFIRE

At 8.18pm on 2 September 1998, Swissair Flight 111 (SR 111), took off from New York’s JFK airport bound for Geneva, Switzerland. Tragically, the MD-11 aircraft never arrived. According to the crash investigation report, published on 27 March 2003, electrical arcing in the ceiling void cabling was the most likely cause of the fire that brought down the aircraft. No one on board was aware of the disaster unfolding in the ceiling of the aircraft and, when a strange odour entered the cockpit, the pilots thought it was a problem with the air-conditioning system. Twenty minutes later, Swissair Flight 111 plunged into the Atlantic Ocean five nautical miles southwest of Peggy’s Cove, Nova Scotia, with the loss of all 229 lives on board. In this paper, the Computational Fluid Dynamics (CFD) analysis of the in-flight fire that brought down SR 111 is described. Reconstruction of the wreckage disclosed that the fire pattern was extensive and complex in nature. The fire damage created significant challenges to identify the origin of the fire and to appropriately explain the heat damage observed. The SMARTFIRE CFD software was used to predict the “possible” behaviour of airflow as well as the spread of fire and smoke within SR 111. The main aims of the CFD analysis were to develop a better understanding of the possible effects, or lack thereof, of numerous variables relating to the in-flight fire. Possible fire and smoke spread scenarios were studied to see what the associated outcomes would be. This assisted investigators at Transportation Safety Board (TSB) of Canada, Fire & Explosion Group in assessing fire dynamics for cause and origin determination.

The AASK database V4.0: aircraft accident statistics and knowledge. A database to record human experience of evacuation in aviation accidents

This paper describes the AASK database. The AASK database is unique as it is a record of human behaviour during survivable aviation accidents. The AASK database is compiled from interview data compiled by agencies such as the NTSB and the AAIB. The database can be found on the website http://fseg.gre.ac.uk

Proposed methodology for the use of computer simulation to enhance aircraft evacuation certification

In this paper a methodology for the application of computer simulation to evacuation certification of aircraft is suggested. This involves the use of computer simulation, historic certification data, component testing, and full-scale certification trials. The methodology sets out a framework for how computer simulation should be undertaken in a certification environment and draws on experience from both the marine and building industries. In addition, a phased introduction of computer models to certification is suggested. This involves as a first step the use of computer simulation in conjunction with full-scale testing. The combination of full-scale trial, computer simulation (and if necessary component testing) provides better insight into aircraft evacuation performance capabilities by generating a performance probability distribution rather than a single datum. Once further confidence in the technique is established the requirement for the full-scale demonstration could be dropped. The second step in the adoption of computer simulation for certification involves the introduction of several scenarios based on, for example, exit availability, instructed by accident analysis. The final step would be the introduction of more realistic accident scenarios. This would require the continued development of aircraft evacuation modeling technology to include additional behavioral features common in real accident scenarios.

Aircraft accident statistics and knowledge database: analyzing passenger behavior in aviation accidents

The Aircraft Accident Statistics and Knowledge (AASK) database is a repository of passenger accounts from survivable aviation accidents/incidents compiled from interview data collected by agencies such as the US NTSB. Its main purpose is to store observational and anecdotal data from the actual interviews of the occupants involved in aircraft accidents. The database has wide application to aviation safety analysis, being a source of factual data regarding the evacuation process. It also plays a significant role in the development of the airEXODUS aircraft evacuation model, where insight into how people actually behave during evacuation from survivable aircraft crashes is required. This paper describes the latest version of the database (Version 4.0) and includes some analysis of passenger behavior during actual accidents/incidents.

A computational study of the characteristics of aircraft post-crash fires

Full-scale furnished cabin fires have been studied experimentally for the purpose of characterising the post-crash cabin fire environment by the US Federal Aviation Administration for many years. In this paper the Computational Fluid Dynamics fire field model SMARTFIRE is used to simulate one of these fires conducted in the C-133 test facility in order to provide further validation of the computational approach and the SMARTFIRE software. The experiment involves exposing the interior cabin materials to an external fuel fire, opening only one exit at the far end of the cabin (the same side as the rupture) for ventilation, and noting the subsequent spread of the external fire to the cabin interior and the onset of flashover at approximately 210 seconds. Through this analysis, the software is shown to be in good agreement with the experimental data, producing reasonable agreement with the fire dynamics prior to flashover and producing a reasonable prediction of the flashover time i.e. 225 seconds. The paper then proceeds to utilize the model to examine the impact on flashover time of the extent of cabin furnishings and cabin ventilation provided by available exits

CAA paper 2006/01: a database to record human experience of evacuation in aviation accidents: the aircraft accident statistics and knowledge database (AASK)

This report concerns the development of the AASK V4.0 database (CAA Project 560/SRG/R+AD). AASK is the Aircraft Accident Statistics and Knowledge database, which is a repository of survivor accounts from aviation accidents. Its main purpose is to store observational and anecdotal data from interviews of the occupants involved in aircraft accidents. The AASK database has wide application to aviation safety analysis, being a source of factual data regarding the evacuation process. It is also key to the development of aircraft evacuation models such as airEXODUS, where insight into how people actually behave during evacuation from survivable aircraft crashes is required. With support from the UK CAA (Project 277/SRG/R&AD), AASK V3.0 was developed. This was an on-line prototype system available over the internet to selected users and included a significantly increased number of passenger accounts compared with earlier versions, the introduction of cabin crew accounts, the introduction of fatality information and improved functionality through the seat plan viewer utility. The most recently completed AASK project (Project 560/SRG/R+AD) involved four main components: a) analysis of the data collected in V3.0; b) continued collection and entry of data into AASK; c) maintenance and functional development of the AASK database; and d) user feedback survey. All four components have been pursued and completed in this two-year project. The current version developed in the last year of the project is referred to as AASK V4.0. This report provides summaries of the work done and the results obtained in relation to the project deliverables.

Predicting the likely impact of aircraft post crash fire on aircraft evacuation using fire and evacuation simulation

The SMARTFIRE Computational Fluid Dynamics (CFD) fire field model has successfully reproduced the observed characteristics including measured temperatures, species concentrations and time to flashover for a post-crash fire experiment conducted by the FAA within their C-133 cabin test facility. In this test only one exit was open in order to provide ventilation for the developing cabin fire. In real post-crash fires, many exits are likely to be open as passangers attempt to evacuate. In this paper, the likely impacts on evacuation of a post-crash fire in which various exiting combinations are available are investigated. The fire scenario, investigated using the SMARTFIRE software, is based on the C-133 experiment but with a fully furnished cabin and with four different exit availability options. The fire data is imported into the airEXODUS evacuation simulation software and the resulting evacuations examined. The combined fire and evacuation analysis reveals that even though the aircraft configuration is predicted to comfortably satisfy the evacuation certification requirement, when fire is included, a number of casualties result, even from the certification compliant exit configuration.

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.