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SRK Coleshaw
INVESTIGATION OF
REMOVABLE EXITS AND WINDOWS
Investigation of Removable Exits and Windows
For Helicopter Simulators
CONFIDENTIAL REPORT
SC 153
SRK Coleshaw
5 Pitmurchie Rd
Kincardine O'Neil
Aboyne
Aberdeenshire
AB34 5BF
Submitted to:
OPITO
Minerva House
Bruntland Road
SRK Coleshaw commercial reports may not be published, except in full, unless permission for an approved abstract has previously been obtained from the author. This report is supplied for the purposes of the client only. The author accepts no responsibility to any other person.
Acknowledgements
Grateful thanks are offered to the many OPITO-approved training providers who willingly provided information about their training facilities and methods. Special thanks go to those organisations who also gave the author free access to observe helicopter underwater escape training incorporating the operation of emergency exits. The knowledge gained has been invaluable in the completion of this work.
About the author:
Susan Coleshaw (PhD, BSc, FErgS) is an independent research consultant working in the field of offshore, marine and aviation safety. Her background is in human applied physiology. Specialist interests include cold-water survival, helicopter underwater escape, personal protective equipment and human performance in emergency situations. Major projects have included a study of stress in survival course trainees, an investigation of the human factors associated with escape from a side-floating helicopter and a review of the benefits and disadvantages of using emergency breathing systems (EBS), the latter project including the development of a draft technical standard for EBS.
Contents
2.1 Review of helicopter escape simulators 5 2.2 Review of emergency exits in real helicopters 5 2.3 Escape procedures and training 5 2.4 Development of a design specification for exits 5 3.0 REVIEW OF HELICOPTOR ESCAPE SIMULATORS 7 3.1 Results of helicopter simulator survey 7 4.0 REVIEW OF EMERGENCY EXITS IN REAL HELICOPTERS 10 4.1 Aviation legislation relating to evacuation and escape 11 4.2 Emergency exit requirements 11 4.3 Guidance on Escape windows 12 4.4 Exit mechanisms and design 13 4.5 Use of exits in water impact accidents 16
4.6 Conclusions 18
5.0 TRAINING PROCEDURES 19
5.1 HUET research 19
5.2 Survey of HUET training with exits 20
5.3 Training good practice 21
5.4 Conclusions and recommendations for training with exits 22 6.0 DEVELOPMENT OF A DESIGN SPECIFICATION FOR EXITS 25
6.1 General 25
6.2 Escape window for underwater escape 25 6.3 Emergency exit for dry and surface evacuation 26
7.0 CONCLUSIONS 27
8.0 REFERENCES 29
ACRONYMS
BOSIET Basic Offshore Safety Induction and Emergency Training
CAA Civil Aviation Authority
EBS Emergency breathing system
EASA European Aviation Safety Authority FOET Further Offshore Emergency Training HUET Helicopter Underwater Escape Training
OPITO Offshore Petroleum Industry Training Organisation OLF Norwegian Oil Industry Association
UKOOA UK Offshore Operators Association
DEFINITIONS
Ditching – An emergency landing on water, deliberately executed, with the intent of abandoning the helicopter as soon as practical.
Emergency exit – a movable door / hatch / window / panel providing an unobstructed opening, suitable for emergency evacuation of the helicopter. This opening should admit a 483 by 660 mm (19" by 26") ellipse. Means of opening should be simple and obvious and must not require exceptional effort.
Escape window – a window fitting a rectangular aperture with a minimum acceptable size of 432 by 355 mm (17" by 14"), suitable for underwater escape in the event of capsize or submersion of the helicopter. Means of opening should be rapid and obvious.
Crash landing – a landing involving high impact velocities and a significant or total loss of control.
MANAGEMENT SUMMARY
This report, commissioned and funded by OPITO, aims to investigate helicopter emergency exits and evaluate the possibility and means of providing a generic exit for helicopter underwater escape training simulators.
A survey of OPITO-approved training providers was conducted initially to determine the range of helicopter simulators currently in use, the type of training being carried out using exits, and some basic information about the types and design of exit in use. Nine designs of helicopter simulator were reported, produced by seven different manufacturers. All of the training providers who responded to the questionnaire were undertaking training with exits. The majority were using some type of push-out window, and most, but not all, used an exit operated by some type of lever mechanism.
A review of exits in real helicopters highlighted differences in the means of evacuation and escape that would be used in a controlled ditching or in an underwater escape following submersion or capsize. Helicopters operating over water and certified for ditching are required to have at least one emergency exit above the waterline in each side of the helicopter, meeting at least the dimensions of a Type IV exit if carrying 9 passengers or less, or a Type III exit if carrying 10 passengers or more (see Section 4). This Type III or IV emergency exit is likely to be the main access door. In a controlled ditching accident, reports have shown that the door could be operated by a crew member or by one of the passengers. In the event of an accident involving capsize or submersion, evidence shows that passengers are most likely to use a push-out window to escape. These 'escape windows', being smaller than a designated emergency exit, are not currently regulated, although the UK Civil Aviation Authority provides guidance on recommended minimum dimensions. There is therefore a need to train passengers to operate both a generic Type III or IV design of emergency exit during a dry or surface evacuation exercise, and to operate a push-out escape window during underwater escape exercises.
A survey of delegates undergoing training using exits showed that most considered that the operation of exits should be included in OPITO training exercises. Of those interviewed, the majority found that the exits used were easy to operate and did not consider the operation of the exit mechanisms to be the most difficult aspect of underwater escape. That said, care must be taken to ensure that training with exits does not increase the level of stress experienced by delegates. This could be achieved by Section 6). Research has shown that close physical fidelity is not necessarily needed for transfer of training (Section 5). Operational realism, functional similarity and consideration of the tasks that must be performed during helicopter escape are more critical. Training should therefore include actions such as the operation of levers, pulling tabs and pushing out the window, if training is to be realistic.
1.0 INTRODUCTION
1.1 BACKGROUND
Mr Iain Emslie of OPITO approached SRK Coleshaw (Independent Consultant) regarding
a proposed revision of the OPITO standards on BOSIET (Basic Offshore Safety Induction and Emergency Training) and FOET (Further Offshore Emergency Training). It had been proposed to incorporate the operation of emergency exits into helicopter underwater escape training (HUET) in BOSIET & FOET standards. The rationale for this change was that "The operation of the emergency exit is seen as the last link in the survival chain during underwater escape. At present the training misses out this link and trainees never practice the skills or techniques involved despite practicing all other aspects of escape. Various reports and studies (e.g. Cranfield report) have recommended more “realistic” HUET training including the operation of emergency exits. HUET training standards in other countries (e.g. Norway, Netherlands) include the use of exits and UK personnel
have had to do additional training to work in other sectors" (OPITO, 2006a).
Proposed changes to the training programme, including seven HUET exercises, were put out for consultation with the offshore industry. Feedback covered a number of issues. The main concerns related to the level of realism created by the training, and the benefits of such realism. Some comments were positive, looking for all delegates to receive an opportunity to remove an emergency exit, whilst others were negative and did not support the need for this additional training exercise:
"From those in favour of making the exit from a helicopter more realistic - an easily removed window (Velcro fastened for example) does not really achieve the objective of familiarising the individual with the operation and may in fact mislead the trainee
faced with a real situation".
"Many feel that we do people a disservice by suggesting that the only way we can train them to operate an exit mechanism, even as part of a sequence of actions, is
to have them do it repeatedly and to do it underwater".
"Define HUET exits as ‘push out’ windows and mechanically operated doors and have delegates rotate through seating positions for each HUET exercise. This would ensure standardisation across training providers and ensure each delegate
had the opportunity to practice with each type of exit".
The windows are a lot easier to take out than I thought they would be, and the procedure for their removal is fully explained. Also the divers in the water can remove the windows from the outside, so if there is the slightest sign that you're not managing, they'll take the window out for you.
A view was expressed that the escape mechanisms used in training should have sufficient fidelity to replicate the operation of exits fitted to helicopters used regularly by the offshore workforce. The need for high levels of physical fidelity in training has been questioned by Summers (1996) who stated that the most important factors in simulator training are operational realism and functional similarity. In the second Workgroup meeting (OPITO, 2006b) it was agreed that emergency exits "may be 'push out' type as opposed to having
a mechanism to operate". The exit designs, means of operation and level of fidelity of
There was also concern regarding the definition and understanding of the term 'exit mechanism': "The term 'exit mechanism' regarding helicopter escape may not be clear enough. I know what is meant by this but it could be interpreted to mean that the delegate is required to operate a handle/remove a beading/press a button, but not actually remove
an exit. Should the wording be 'operation of an emergency exit'?". This last point was
taken up by the OPITO Workgroup (OPITO, 2006b) who, in response to the concern that the statement "operate an exit mechanism" could be interpreted in a number of ways, decided to change this wording to "operate an emergency exit".
One respondent made the case that delegates should have the opportunity to undertake a cross-cabin escape from a seat not positioned next to an exit: "In the simulator all 4 personnel will be situated next to an escape route (window) with uninterrupted egress. In a live situation several personnel will not be next to a window and training should be given
for this type of scenario". Whilst this would go further to increasing the realism and fidelity
of training, it could have safety disbenefits and could increase the stress of training, an additional factor also being reviewed at the current time.
Finally, there were comments relating to the time needed to undertake the seven exercises: "The number of HUET exercises and the need to reinstate pop-out windows between drills will inevitably lead to longer periods of standing around waiting to take part in an exercise. People already comment unfavourably on the amount of standing around
and “non-productive” time on these courses and see this as worsening in the new regime".
Similarly, one respondent was concerned to remove any exercises that did not increase the level of learning: "Can the BOSIET requirement for Helicopter Escape be compressed? If you can escape with the window 'in-place', is it necessary to train with the
window removed"? Consideration must therefore be given to the benefits of each
proposed exercise to ensure that training outcomes are improved whilst taking account of trainee views that courses are already too long and repetitive.
In July 2006 it was agreed that a Work Group should be set up to look at exit designs and produce a specification for the type of exits to be used in training (OPITO, 2006b). OPITO subsequently decided that an independent consultant should undertake this work, liaising with the training providers and equipment manufacturers.
It should be noted that a concurrent study was undertaken to address concerns over the levels of stress that are experienced by delegates undergoing helicopter underwater escape training and investigate the implications of higher fidelity training using exits. The results of the stress study (Coleshaw, 2006) were considered when reviewing the training methods within this investigation relating to the design of emergency exits.
1.2 AIMS AND OBJECTIVES
The overall aims of this project were thus to evaluate the means of providing a generic emergency exit (with 'operational realism') for use in the range of helicopter underwater escape simulators currently in use and to review the escape training procedures in relation to seat position, type of emergency exit and number of exercises needed to improve the training outcomes.
The objectives are to:
Review the designs of helicopter underwater escape simulators currently in use, giving particular consideration to the design of 'removable' emergency exits;
Review the design of 'real' emergency exits and determine the exit design features required to provide a suitable level of operational realism;
Produce a design specification based on the above;
Determine whether this generic emergency exit can be fitted/retro-fitted to the helicopter simulators currently in use;
Reconsider escape procedures and options for rotating passengers round the various seating positions;
2.0 METHODS
2.1 REVIEW OF HELICOPTER ESCAPE SIMULATORS
A questionnaire (Appendix 1) was sent to 20 OPITO-approved training organisations undertaking BOSIET and FOET emergency response training (eight in the UK and a further 12 located worldwide). The questionnaire had the objective of gathering some basic information about the types and designs of helicopter underwater escape simulator currently in use, whether the training providers undertook HUET training incorporating the operation and removal of exits (non-OPITO approved) and if so, the types and designs of emergency exits and windows used. The data was collated to define the range of equipment used and assess the practicalities of developing a generic design of exit. Four training organisations in the UK, each operating different designs of HUET simulator, were then visited. Training involving the use of removable exits was observed and the equipment was photographed. Both training staff and course delegates were interviewed to determine their views on ease of operating the exits (see Coleshaw, 2006).
2.2 REVIEW OF EMERGENCY EXITS IN REAL HELICOPTERS
A study of exits in real helicopters was undertaken to determine the degree of fidelity required when using exits during HUET training.
Legislation was reviewed to identify the correct definition and design requirements for different types of exit.
2.3 ESCAPE PROCEDURES AND TRAINING
Accident reports were reviewed to investigate the different evacuation and escape routes used under different ditching and crash scenarios and any problems experienced when passengers attempted to operate exits.
Research papers investigating helicopter underwater escape performance were also reviewed, again to determine problems experienced and to provide information about ease of escape and optimum training procedures.
Lessons learnt from the stress study, when delegates and training staff were questioned about HUET training using (emergency breathing systems) EBS and exits, were taken into account when considering training exercises for the BOSIET and FOET courses.
2.4 DEVELOPMENT OF A DESIGN SPECIFICATION FOR EXITS
3.0 REVIEW OF HELICOPTOR ESCAPE SIMULATORS
3.1 RESULTS OF HELICOPTER SIMULATOR SURVEY
A survey of HUET facilities used by OPITO-approved training organisations worldwide provided evidence of a wide range of helicopter simulators currently in use. Table 1 summarises the data collected. Responses were received from all 8 of the UK training providers contacted and from 4 of the 12 other training providers contacted worldwide. Of the 12 training providers who responded, 9 designs of HUET simulator were recorded, made by 7 different manufacturers. Appendix 2 shows photographs of most of these designs.
All of these training providers currently conducted HUET training with some type of exit. Push-out windows were used by 10 of the 12 training providers. Doors, exits or windows operated by rotation of a lever or handle were used by 10 of the 12 training providers. Of those operating push-out windows, 5 used designs with a rubber seal that was removed using a pull-tab prior to pushing out the window. In some cases Velcro held the window in place. In others, a system of ball bearings held the window in place. Photographs of a selection of the exits/push-out windows currently in use are shown in Appendix 2. No information was obtained from the equipment manufacturers regarding the amount of pressure required to remove the push-out windows. In most cases, mechanisms were adjusted with the aim of ensuring that operation by delegates could be achieved with a moderate amount of pressure.
One training provider undertaking training on behalf of Shell for operations in the Gulf of Mexico also used a shallow water training device to familiarise delegates with the underwater operation of exits before undertaking exercises in the HUET simulator. This device is shown in Figure 1.
Table 1: Results of helicopter simulator survey
Training Provider HUET Type Seats next to removable exit/window
Exit types / mechanisms Window types / mechanisms
United Kingdom
FalckNutec Aberdeen METS 30,
Survival Systems
7 Rotate lever, push out exit Pull tab/push out window Push-out window
FalckNutec Teesside METS 40,
Survival Systems
8 Rotate lever, push out exit Pull tab/push out window Rotate lever
Fleetwood EDM 4 Removable doors Rotate lever
Push-out window
HOTA Partoria Engineering 4
(2 next to window)
Half door with release lever (2) Pull tab/push out window Push-out window
PETANS Small & Co, Lowestoft 4 Rotate lever, push out exit Rotate lever
Table 1 (continued)
Training Provider HUET Type Seats next to removable exit/window
Exit types / mechanisms Window types / mechanisms
Rest of World
3 Door with pull-down handle (2) Push-out window (2)
RGIT Montrose Inc.
USA
METS Mk5, Survival Systems
4 Lever pulls out at right-angle to exit, door jettisoned (2)
4.0 REVIEW OF EMERGENCY EXITS IN REAL HELICOPTERS
4.1 AVIATION LEGISLATION RELATING TO EVACUATION AND ESCAPE
Emergency evacuation and escape equipment on helicopters is designed to cover all types of incident, including both controlled and uncontrolled impacts on land and water. It is a requirement that crew and passenger areas must have means for rapid evacuation, considering amongst other issues the possibility of fire (JAR/FAR 29.803). In the event of an impact on land, passengers are likely to be evacuated using the main cabin door, this being a large sliding door in many cases.
In the event of a ditching or controlled landing on water, under reasonably probable water conditions, the flotation time of the helicopter should provide sufficient time, at least five minutes, for the occupants to leave the helicopter and enter the liferafts (JAR/FAR & 27.801 29.801). Many exit doors are capable of jettison when the helicopter is in the upright condition. Doors designated as emergency exits that cannot be jettisoned are required to have a means of securing them in the open position so that they do not interfere with occupants egress in all sea conditions (JAR-OPS 3.837 (a)(5); 2004).
However, it is recognised that in the event of either an intentional ditching into rough water or an uncontrolled water impact, the helicopter may suffer serious damage, making it highly probable that the helicopter will either sink or capsize. Under these conditions there is also a risk that the flotation equipment will be damaged, again increasing the probability of capsize. In this event, crew and passengers will of necessity have to escape underwater, using either an emergency exit or escape window. For this reason, European regulations relating to helicopters operating to or from helidecks located in a hostile sea area (JAR-OPS 3.837 (a)(6); 2004) call for "all doors, windows or other openings in the
passenger compartment authorised by the authority [EASA] as suitable for the purpose of
underwater escape, are equipped so as to be operable in an emergency".
4.2 EMERGENCY EXIT REQUIREMENTS
Helicopters certified with ditching provisions (i.e. for over-water operations), must have a minimum of one emergency exit on each side of the cabin readily accessible to each passenger, that is above the waterline and that opens without interference from flotation devices (FAR/JAR 27.807).
Emergency exits are variously described in the regulations as "movable doors or hatches" or "a movable window or panel, or additional external door, providing an unobstructed
opening that will admit a 19- by 26-inch ellipse" (JAR/FAR 27.807). Means of opening
each emergency exit are required to be "simple and obvious" and must "not require
exceptional effort" (JAR/FAR 27.807, 29.809). Each passenger emergency exit, its
means of access and means of opening must be conspicuously marked, with instructions for operating handles (JAR/FAR 29.811). Exit markings and location signs must have white letters 1" high on a red background 2" high (these colours may be reversed if this improves visibility). Emergency lighting is also required at each emergency exit (JAR/FAR 29.812).
Table 2: Requirements for emergency exit provision (excluding ditching requirements)
Emergency exits for each side of the fuselage Passenger seating capacity helicopters with a seating capacity of nine passengers or less are required to be provided with one emergency exit above the waterline in each side of the helicopter, meeting at least the dimensions of a Type IV exit. Helicopters certified for ditching, with a seating capacity of ten passengers or more are required to be provided with "one exit above the waterline in a side of the rotorcraft meeting at least the dimensions of a Type III exit, for each unit (or part of a unit) of 35 passenger seats, but no less than two such exits in the passenger cabin, with one on each side of the rotorcraft".
The types of passenger emergency exits have been defined as follows (JAR/FAR 29.807):
Type I - a rectangular opening of at least 610 mm wide by 1219 mm high (24" by
48"), with corner radii not greater than one third the width of the exit, in the passenger area in the side of the fuselage at floor level and as far away as practicable from areas that might become potential fire hazards in a crash.
Type II – the same as Type I, except that the opening must be at least 508 mm wide
by 1118 mm high (20" by 44").
Type III – the same as Type I, except that the opening must be at least 508 mm
wide by 914 mm high (20" by 36"); and the exits need not be at floor level.
Type IV - a rectangular opening of at least 483 mm wide by 660 mm high (19" by
26"), with corner radii not greater than one third the width of the exit, in the side of the fuselage with a step-up inside the helicopter of not more than 737 mm (29").
4.3 GUIDANCE ON ESCAPE WINDOWS
'Escape windows' are not considered 'emergency exits' due to being smaller than the minimum size requirements for an emergency exit. According to Leaflet 11-18 (CAA, 2006) an 'escape window' is a window fitting a rectangular aperture with a minimum acceptable size of is 432 mm x 355 mm (17" x 14"). Underwater escape through a window of this size has been shown to be achievable by the 95th percentile male person wearing survival clothing and an uninflated lifejacket (CAA, 2006). The CAA guidance thus suggests "all suitable openings in the passenger compartment which are of this approximate size or larger need to be considered for designation as an additional escape route in the event of capsize, and made openable. The means of opening should be rapid
and obvious". It also suggests that placarding and passenger briefing be used to ensure
Two groups have recommended changes to the current JAR/FAR Regulations Parts 27 and 29, as described in CAA Paper 2005/06 (CAA, 2005). The JAA Helicopter Offshore Safety and Survivability (HOSS) working group were concerned that current helicopter ditching requirements preclude the helicopter being capsized by a wave. They cite an accident when a helicopter ditched and then inverted in severe wave conditions and where all 11 passengers and one crew member escaped through 'push-out' windows in the cabin. "Push-out windows were acknowledged as having made a fundamental
contribution to occupant survivability". However, they considered that hand holds close to
the windows would be needed to help occupants to apply sufficient force to ensure removal of the windows. They also considered that emergency lighting systems should be extended to apply to 'push-out' windows, automatically activated following flooding of the cabin. Their third concern related to the high risk of disorientation following a capsize, making location and use of 'push-out' windows difficult and looked at optimising seating configuration to reduce possible escape times. HOSS thus recommended (Appendix F; CAA 2005):
FAR/JAR 27.807 and 29.809 be amended to require that all apertures in passenger compartments suitable for the purpose of underwater escape shall be made openable in such an emergency, and hand holds should be provided adjacent to such apertures to assist their location and operation. Associated advisory material
should be developed to indicate what constitutes a 'suitable' aperture.
Emergency exit marking systems should also be required on 'push-out' windows and be automatically activated following flooding of the cabin.
Seat rows should be aligned with windows.
The FAA/JAA/Industry Joint Harmonisation Working Group on Water Impact (Appendix G; CAA, 2005) recommended:
"All apertures in the passenger compartment suitable for the purposes of
underwater escape shall be equipped so as to be usable in an emergency".
This recommendation was based upon the fact that there were specific regulatory requirements for emergency exits relating to ditching certification, but none for escape routes underwater in the event of a submersion or capsize. They argued that research and accident experience has shown that occupant survivability is improved when the opportunity for emergency egress is increased in a water impact. A rule change for helicopters operating over water would allow push-out windows to be marked with appropriate emergency exit markings and thus improve occupant safety.
4.4 EXIT MECHANISMS AND DESIGN
When considering the ease of use and operation of exits one of the main problems is the wide range of mechanisms found in different helicopter types, their various positions in relation to the exit and the different directions of operation (see RHOSS report, 10.18; CAA, 1995). RHOSS recognised that it must be possible to operate emergency exits in a crash scenario when individuals "may not act in a deliberate and rational manner".
direction, some a pull, some a push action. Whilst many were single action, some had a double action. The position of the operating mechanism differed widely. These authors called for the use of just two operating mechanisms: one mechanism to fit all doors whether they be in the cockpit or in the passenger cabin, and a second operating mechanism for all emergency exits and escape windows.
Some of the passenger cabin doors and emergency exits described included designs used in the offshore industry:
Eurocopter AS-332L / Super Puma door
i. Pull lever down (clockwise; through 60° to down vertical position1) Bell 214 emergency exit
i. Pull lever up (clockwise, through 90° to up vertical position) Sikorsky S-61 stairway
i. Push forward lever;
ii. Rotate lever (clockwise through 90° from left of vertical to right of vertical). Sikorsky S-76 door
i. Pull cover;
ii. Lift up lever at right angles to fuselage.
When considering escape windows, again a number of different means of operation were found (Brooks and Bohemier, 1997):
i. Lift up (using hand recess at base of window); ii. Pull to release; According to an experienced helicopter pilot (personal communication) the most difficult action when operating a push-out escape window is the removal of the beading around the window. In his view, if this is done successfully, the window should not be too difficult to push out.
Figure 1 shows a comparison between the dimensions of the emergency exits and escape windows as defined in the aviation regulations and guidance and the dimensions of two example helicopters, the Eurocopter AS-332L2/Super Puma and the Bell 412. The Super Puma has one door, one Type IV emergency exit and four escape windows, two of which are fitted in the door, on each side of the passenger cabin (Figure 2). The Type IV exit and one escape window are shown in Figure 3. The Bell 412 has two emergency exit windows fitted within a large sliding door, both capable of being jettisoned.
Figure 1: Comparison of actual exits with regulations and guidance JAR/FAR Regulations: CAA Guidance:
Minimum sizes2 Minimum size2 suitable for all passengers including large males
Type IV Emergency exit Push-out window
Eurocopter AS-332L2/Super Puma
Type IV Emergency exitsize2 Push-out window size2
Bell 412
Type IV Emergency exit / push-out window size2
Figure 2: Super Puma door fitted with two escape windows
Figure 3: Type IV emergency exit and escape window in a Super Puma
4.5 USE OF EXITS IN WATER IMPACT ACCIDENTS
Evidence from helicopter accident reports has shown that in about 60% of all water impact accidents, the helicopter either capsizes or sinks (Rice and Greear, 1973; Brooks, 1989; Clifford, 1996). In some cases, capsize is immediate, requiring passengers and crew to escape underwater. In other cases capsize is delayed and occupants may have time to carry out a controlled surface evacuation of the helicopter. Likelihood of capsize is increased by rough sea conditions (very likely in Sea State 6 or above) and by high impact speeds.
which were attributed to drowning. Fatality rates of 26%, 57% and 80% were recorded in vertical descent with limited control, fly-in and uncontrolled impact incidents respectively, where cause of death was known (see Coleshaw, 2003). Cause of death was attributed to drowning in 34%, 42% and 14% of these deaths; the highest proportion due to drowning was thus seen in fly-in incidents.
Without the aid of an emergency breathing system (EBS) the breath-hold time of individuals must exceed escape time if passengers are to have a good prospect of survival (Miles, 2000), particularly in cold sea areas such as the North Sea. Miles commented "every study of underwater escape times from inverted helicopters gives
times which are longer than every study of breath hold times" [in cold water]. Whilst use
of EBS, where provided, should help to increase the time available for escape, passengers must still locate their nearest exit, operate the exit mechanism and make an escape through the exit. Not all seats will be next to an exit making escape more difficult. Those who have to swim or pull themselves to an exit from a remote seat may have difficulty operating the exit due to a lack of hand-holds and difficulty applying pressure to the exit, floating away from it.
In the best-case ditching scenario, the crew may have automatically jettisoned the main exit. This will depend on whether the crew have had sufficient time to carry out this action after undertaking a controlled landing on water. In a ditching incident in the North Sea in 1988 (AAIB, 1990) the crew did not activate the automatic unlatching control of the rear emergency exit and passengers had difficulty operating this exit in smoke.
It has been demonstrated that the cabin door of a Super Puma is very unlikely to jettison if the helicopter has inverted or is other than upright (Bailey, 1990). The emergency release system relies on gravity to release a portion of the sliding door track. In the RHOSS report, it was stated "it is difficult to envisage circumstances in which it would be
practicable to use the main exit when the fuselage is not upright". In the event of a
capsize it is therefore likely that passengers will have to operate either a Type III or IV emergency exit window or a push-out escape window.
In the event of capsize, exit operation becomes much more difficult for a number of reasons. Disorientation means that a passenger is likely to reach in the wrong direction for an exit mechanism, whilst it can also cause errors in a person's perception of the vertical. In the 1988 accident reported earlier (AAIB, 1990) the helicopter capsized shortly after ditching. Both crew had problems reaching the jettison handle for their emergency exit. One of the passengers reported difficulty gripping the rip-tag attached to the beading sealing the push-out window and had to remove his glove to complete the action. A second passenger broke a bone in his hand whilst attempting to push out a window. It can be questioned whether this was due to the force needed to remove the window or because the individual did not know how much pressure would be required and applied maximum force in the stress of the situation.
by individuals who must cross the cabin from these seats is also likely to be more problematic as they must release their harness before reaching the exit, making location and operation of the exit more difficult.
Whilst smoke has been shown to be a problem for surface evacuation, poor visibility is also a problem in underwater escape. Darkness is the obvious cause, with measures taken to light emergency exits. Regulations do not currently require escape windows to be illuminated. Poor visibility was a problem in an incident off the West coast of Scotland, when a curtain of bubbles illuminated by emergency lights obscured the exit mechanism meaning that a crew member could not locate the exit (AAIB, 1989).
4.6 CONCLUSIONS
Minimum dimensions for emergency exits and escape windows can be defined; Most emergency doors used for evacuation operate by use of a handle rotation; In a surface evacuation the crew may not be available to operate the exit door and coordinate an emergency evacuation. Passengers must therefore be familiar with the operation of the exit door release mechanism;
Following capsize, passengers must escape as quickly as possible, using either a Type III or IV emergency exit or a push-out type escape window. Passengers must therefore be familiar with and capable of operating both emergency exits and escape windows located in the passenger cabin;
The majority of push-out windows incorporate a seal that must be removed before the window can be jettisoned;
Visibility of exits may be impaired by factors such as smoke, darkness, bubbles; In the event of a submersion or capsize, time taken to escape is dependent on the time to locate and operate an emergency exit or escape window;
Disorientation will make the location of exit mechanisms and escape more difficult; Problems have been experienced using the pull-tags on window seals. Gloves may make this action more difficult.
Not all seats will be next to an exit making escape more difficult;
5.0 TRAINING PROCEDURES
5.1 HUET RESEARCH
A number of research investigations have looked at the issue of improving the fidelity of HUET training. The term fidelity is used to describe the degree to which helicopter simulators represent the real environment within a helicopter and how closely evacuation and escape training procedures match the process that may be experienced in a real water impact incident. It is generally assumed that the closer the match and the higher the degree of similarity, the better will be the transfer of knowledge to the real situation. According to Summers (1996) close physical fidelity is not necessarily needed for transfer of training. Fidelity is determined by task analysis, which identifies the information required for learning and focuses on the actions that the individual will have to undertake rather than a close representation of the helicopter environment. Summers states "essentially, it is the operational realism or functional similarity which determines fidelity in
simulation and not face validity based on physical similarity of devices". Summers cites
as an example a study where training in a plywood aircraft cockpit mock-up produced transfer of training that was similar to that achieved with a high fidelity, sophisticated and expensive cockpit simulator.
From this research it can be concluded that, in developing training procedures, attention should focus primarily on the actions and sequence of events undertaken by delegates. The similarity of equipment should be a secondary consideration. Thus, when training delegates to operate an exit, it will be important to ensure that all actions, such as pulling on a tab to remove a seal before pushing out a window, are included in the escape procedures taught.
Summers (1996) also investigated refresher training and concluded that relatively simple retraining methods may be sufficient for upgrading procedural skills particularly if the task was initially learned on the operational equipment. This suggests that learning about the operational environment by helicopter type-specific briefings, videos and safety cards is an essential part of the overall learning process.
A study aimed at developing a training standard on behalf of Shell (Muir and Mills, 1999) concluded that delegates must be given training and practice in the operation of representative exits if they are to meet minimum competency levels. They found that the training received significantly influenced the time taken by participants to operate an exit window in an inverted simulator ('METS'). The time taken to operate the exit directly influenced the overall time taken to escape. They considered that transfer of training was dependent upon the operational environment and the force needed to operate an exit being similar to the real situation.
A more recent study (Kozey et al, 2006) also investigated the effects of training fidelity and practice on egress performance. Participants were split into three groups. Group 1 undertook two training exercises: one partial submersion and one inversion, both without windows to push out. Group 2 undertook three exercises: one partial submersion without a window to push out, one inversion without a window to push out and one inversion during which a window had to be pushed out to make a successful escape. Group 3 undertook six exercises: one partial submersion without a window to push out, one inversion without a window to push out and four inversions during which a window had to be pushed out to make a successful escape. During training, the operation of exits for the first time underwater decreased the pass rate, but with repeated training, success rates increased.
Six months after the training, participants returned to complete a single underwater escape test including the operation of the push-out windows. Performance was evaluated on the basis of passing or failing the attempt to make a successful escape. The escape test results are reproduced below:
Group Pass Fail Total
1 28 (54%) 24 (46%) 52
2 38 (81%) 9 (19%) 47
3 52 (96%) 2 (4%) 54
Training that included the operation of exits significantly improved the escape success rate from 54% to 81%. There was a further significant improvement to a 96% success rate observed for the Group who had also had the opportunity to practice underwater escape with exits during their training. These results clearly demonstrate the combined benefits of including the operation of exits during training and of practicing underwater escape using exits.
5.2 SURVEY OF HUET TRAINING WITH EXITS
A survey of 42 delegates undertaking HUET training with exits, previously reported by
remove exits during HUET training'. (N.B. It should be noted that these delegates used
four quite different designs of push-out window).
When rating the most difficult aspects of HUET training, no delegates cited removing the exit/window as being the most difficult factor. Disorientation was considered by 50% of the group to be the most difficult factor, whilst 21% considered use of EBS to be most difficult.
Comments relating to exits and training in general included: "More realistic window design".
"If anything, more realistic".
"Window seats should only be manned by people who have done HUET with door
"Needs to be more realistic. Window seals. Door to operate."
Suggestion to block an exit so that delegate must escape through a different exit. "Water section needs to be longer. Less people i.e. <16 in pool".
"Too many in water session [16]. Longer time would be helpful to raise confidence".
"Halve no. of delegates. More time with apparatus. More 'dunks'". "Would benefit from smaller class size".
"Maybe lights out, wave machine, sea conditions".
"Some way for individuals to experience being turned upside down in some smaller equipment to get over apprehension without having to try and get out of the HUET simulator".
"Have smaller groups i.e. 8 at a time not 16, split to give more time to get to know
equipment".
It can be seen that a number of comments called for training to be made more realistic by the inclusion of exits. The other common theme related to smaller group sizes.
5.3 TRAINING GOOD PRACTICE
Whilst observing the HUET training and talking to delegates and training staff a number of other issues were noted that could be regarded as good training practise.
1. Instruction during wet/shallow water training with a staff to student ratio of 1 to 4 reduced the likelihood of peer pressure and allowed training staff to give more individual attention to the needs of each delegate. (The likelihood of an individual admitting problems within a group size of 8 or more is low, particularly if this action was likely to hold up the training of others who were anxious to complete the course as quickly as possible).
2. In some cases, the competence of delegates using EBS was assessed on a 1:1 basis allowing the member of staff to assess, not only whether the delegate was completing the required actions in the correct order and manner, but also allowing them to assess the confidence of each individual when using the equipment. This practice would allow staff to fast-track individuals who found the equipment easy and simple to use, and give those having problems more time to gain confidence as well as competence.
3. Time spent completing initial wet/shallow-water training allowed delegates to practice using the equipment (EBS in this case), gain confidence and overcome problems and fears. This appeared to reduce the impact of the exercises undertaken in the helicopter simulator.
4. There are two options for completing the HUET exercises. The first is to take each group (usually 4 delegates) through all the exercises, before moving on to the next group. This practice may involve a long wait for the last group. The preferred option is to split the HUET exercises so that each group completes the surface evacuation and partial submersion exercises before then moving on to the capsize exercises. This also gives delegates a short break and may be important when 7 exercises are being considered for BOSIET training.
training. It is considered that delegates could be given the opportunity to operate a push-out window in a controlled environment, either using a window mock-up in shallow water or using a window within the simulator. This could be undertaken whilst using EBS, allowing the delegate time to overcome any fears about their ability to remove a push-out window.
One of the other issues raised during the consultation process related to cross-cabin exercises and escape from seats that are not located next to a window. Underwater escape exercises of this type have been undertaken in the past and were generally stopped for safety reasons. In this case exercises were undertaken with more than 4 delegates, meaning that some had to hold their breath and wait for the person next to the exit to escape before they could escape. Some minor injuries occurred. In recent years it is much more common for each delegate to be placed next to an exit. One of the training providers consulted during the survey reported problems conducting multiple cross-cabin egress exercises with windows but no EBS. Two delegates suffered from water ingestion. The exercise is now optional. The representative from the training organisation considered that it was difficult to control the risks with this type of exercise. It is therefore suggested that if cross-cabin exercises are to be considered, they should be carried out with a small number of delegates in the HUET, with only one delegate leaving by each window and no crossed escape routes.
5.4 CONCLUSIONS AND RECOMMENDATIONS FOR TRAINING WITH EXITS
By including the operation of exits in emergency response training, particularly the push-out escape windows predominantly used when a helicopter capsizes, it is hoped that escape times in a real accident can be decreased, and that the incidence of drowning may thus be reduced.
In the event of a real helicopter ditching, the best scenario is one where passengers are evacuated from the helicopter cabin into a liferaft, under the supervision of a crew member and using a door exit. The worst-case scenario would be an uncontrolled landing on water, where submersion and/or capsize occur almost immediately. In this event, it is most likely that passengers will be required to make an escape through a submerged Type III or IV emergency exit or through an escape 'push-out' window. Two types of generic exit mechanism are likely to be encountered, an emergency exit operated by a lever mechanism requiring rotation of a handle, and a push-out window requiring location of a pull tab and removal of a seal before pushing out the window.
Example design specifications for (1) a training push-out window and (2) a training door exit are provided in Section 6 of this report.
The following recommendations are made relating to training procedures using exits: 1. Classroom briefing that includes some discussion about the types of emergency exit
and escape window mechanisms that may be experienced in real helicopters. Reference should be made to the fact that, at the current time, emergency exits will be marked as exits and will be illuminated in an emergency whereas escape windows may not be marked or illuminated.
operate a push-out window in the submerged HUET. EBS should be used for this exercise, providing additional beneficial practice in the use of EBS.
3. In the dry evacuation exercise (dry landing), delegates will be instructed to evacuate the cabin using a door exit. Delegates should be given the opportunity to operate this exit mechanism, preferably by rotating a lever mechanism.
4. In the surface evacuation exercise (ditching/controlled landing on water), delegates should be given the opportunity to operate a push-out window, as a precautionary measure, remaining in their seats after jettison of the window. They will then be instructed to carry out a controlled evacuation to the liferaft using the door exit. 5. At least one capsize exercise (180° inversion) should be conducted where
delegates are required to operate and escape through a push-out window. EBS should be used during this exercise.
6. During FOET training, delegates could be given the opportunity to undertake an additional exercise where they start in a seat that is not located next to a window. For safety reasons, the window seat should be left empty. This exercise should not be mandatory but would extend the learning of those who are confident completing HUET training. If undertaken, to control the risks, this exercise should be conducted with a small number of delegates in the HUET, with only one delegate leaving by each window and no crossed escape routes.
6.0 DEVELOPMENT OF A DESIGN SPECIFICATION FOR EXITS
6.1 GENERAL
This research has shown that when developing a possible design specification for a generic exit to be used in helicopter underwater escape training, two options must be considered: (1) an emergency exit involving rotation of a lever mechanism; (2) an escape window that is pushed out by the operator. In the event of a controlled ditching on water, passengers are likely to be evacuated from the cabin via a door or emergency exit involving a lever-type mechanism. In the event of capsize, the evidence suggests that most passengers will escape using a push-out 'escape' window.
The generic designs of exit for training are based on the above assumptions. Consideration has been given to the minimum sizes described in regulations and guidance, and to the size of actual exits and windows used in helicopters currently in use for offshore operations.
Consideration has also been given to the ease of escape through the exits during training exercises. A certain degree of fidelity is required without making escape too difficult and therefore too stressful for some. The minimum width of the exits should be sufficient to accommodate the 95th percentile member of the adult male population. A recent anthropometric study provides British, European and World data for the bideltoid shoulder width of males (Quigley et al, 2001):
Bideltoid Shoulder Width 95th %ile 99th %ile British 536mm (21.1") 565mm (22.2")
European 536mm (21.1") 565mm (22.2")
World 563mm (22.2") 608mm (23.9")
The authors of this paper recommended using the 99th %ile dimension (for aircraft seat size) on the basis that the numbers of heavily built people in Western populations is growing. If this argument is followed then it seems appropriate to ensure that the maximum width of a training exit accommodates a person of this shoulder breadth i.e. 608mm (23.9")
6.2 ESCAPE WINDOW FOR UNDERWATER ESCAPE
Figure 3: Suggested maximum and minimum size of push-out window to be used for underwater escape exercises.
6.3 EMERGENCY EXIT FOR DRY AND SURFACE EVACUATION
The size of this exit is less critical as emergency exit doors are large enough not to restrict egress. Dimensions have therefore not been specified. It is recommended that this simulated emergency exit be operated by either a lever mechanism or as a sliding door. To increase the fidelity of these exits it is considered that the exit doors used for training should be marked as an exit using white letters on red or red letters on white as per the regulations for emergency exits (Section 4.2). This would be cheap and simple to achieve but would increase the fidelity of the exits.
Similarly, it is suggested that the exits should be fitted with something to represent the regulatory exit lighting. This could be achieved by the use of strips of retro-reflective tape around the exit.
7.0 CONCLUSIONS
A wide range of HUET simulators and exits are currently in use. There is therefore a need for flexibility in defining generic exits, which can be fitted to all designs of simulator.
Operational realism, functional similarity and consideration of the tasks that must be performed during helicopter escape are more critical than physical fidelity. Training should therefore include a requirement to learn the actions involved in the operation of:
o An exit door, preferably with lever a mechanism, for dry and surface
evacuation;
o A push-out window for underwater escape.
Recommended 'generic' exit specifications should be based on the regulations and published guidance relating to emergency exits and escape windows and to estimates of population size.
8.0 REFERENCES
AAIB (1989) Report on the Accident to the Sikorsky S61N Helicopter G-BDII, near Handa Island off the north-west coast of Scotland, on 17 October 1988. Report no. 3/89. London: HMSO. ditching in water. RTO AG 305E. Neuilly Sur Seine; AGARD. ISBN 92-835-0522-0. Brooks CJ, Bohemier AP (1997) Helicopter door and window jettison mechanisms for underwater escape: ergonomic confusion! Aviat. Space Environ. Med. 68: 844-857.
CAA (2002) Helicopter emergency escape facilities. Airworthiness Information Leaflet AIL/0124, Issue 2, 18 July 2002.
CAA (2005) Summary report on helicopter ditching and crashworthiness research. CAA Paper 2005 / 06. Norwich, TSO.
CAA (2006) Leaflet 11-18. Helicopter emergency escape facilities. In: Civil Aircraft Airworthiness Information and Procedures. CAP 562, Part 11, p3.
Clifford WS (1996) Helicopter crashworthiness. Study 1. A review of UK military and world civil water impacts over the period 1971-1992. CAA Paper 96005. London; Civil Aviation Authority.
Coleshaw SRK (2003) Preliminary study of the implementation and use of emergency breathing systems. CAA Paper 2003/13. Cheltenham; Civil Aviation Authority.
Coleshaw SRK (2006) Stress levels associated with HUET: the implications of higher fidelity training using exits. Report SC155; prepared on behalf of OPITO; November 2006.
Kelley R (2000) Survival after ditching. Shell Report Rev01, March 2001.
Kozey J, McCabe J, Jenkins J (2006) The effect of different training methods on egress performance from the Modular Egress Training Simulator. Paper presented at: IASST (International Association for Safety and Survival Training) Conference; Croatia; October, 2006.
Miles R (2000) Breath hold and escape times: the HSE perspective. Paper presented at Leith International Conference, Aberdeen, November, 2000.
OPITO (2006a) Emergency response standards; Workgroup No 1 Amendment / Rationale. 28-3-2006.
OPITO (2006b) Emergency response standards; Workgroup No 2 Amendment / Rationale. 04-7-2006.
Quigley C, Southall D, Freer M, Moody A, Porter M (2001) Anthropometric study to update minimum aircraft seating standards. University of Loughborough Report prepared for the Joint Aviation Authorities.
Rice EV, Greear JF (1973) Underwater escape from helicopters. In: Proceedings of the Survival and Flight Equipment Association Annual Symposium. Phoenix, Arizona, 1973. pp59-60.
Summers F (1996) Procedural skill decay and optimal retraining periods for helicopter underwater escape training. IFAP Technical Report; Willetton, Western Australia.
APPENDIX 1
HELICOPTER SIMULATOR EMERGENCY EXIT
QUESTIONNAIRE
Please provide as much information as possible. Hatched boxes allow unlimited amounts of text to be entered.
CONTACT DETAILS
Name of training organisation: ……….
Address: ……….
………. ……….
Phone number: ……….
Contact person: ……….
COURSES
Please list emergency response courses offered and check the box on the right for those courses where delegates are required to remove an window/exit during helicopter underwater escape training (please add additional lines if required):
Exits removed? 1.
2. 3. 4.
HELICOPTER SIMULATOR
Manufacturer of helicopter simulator: ………
Brand name / Model? ………
Number of available seats positioned ……… next to a removable exit/window:
Please indicate the type of removable exits and windows currently available at your training organisation and used in HUET training for passengers. Some aircraft types using these mechanisms are indicated in brackets.
Exits
Rotate lever:
(e.g. Super Puma, Bell 214, AS 365N)
Rotate lever and push out exit: (S61)
Pull handle down: (Super Puma)
Lever pulls out at right angle to exit: (S76)
Other? ………
Windows
Pull tab/tape, push out window: (e.g. Super Puma, Bell 214)
Push out window only: (e.g. Bell 214, Bell 412) Rotate lever:
(e.g. S61, S76)
Lift/pull bar, push out window: (e.g. S61)
Other? ………
APPENDIX 2
Examples of HUET simulators
Manufactured by: Carrig Engineering Services, Eire.
Manufactured by: EDM, UK.
Manufactured by McLean & Gibson, UK.
Examples of exit doors and windows
EDM windows:
1. Push-out window held by two ball bearings at the top and two at the base of the window.
2. Similar window operated by lever mechanism.
Window dimensions: 26½" x 19" (670mm x 490mm)
Gulf Tech exits: 1. Door
Dimensions: 46" x 24" (1168mm x 610mm)
2. Push-out window
McLean & Gibson push-out window.
METS Mk5 door and push-out window exits
METS 30 exit options: S61 Back Door: S.61 Cabin Window: Puma Cabin Window: Puma Cabin Window:
