by sounds or other indications. One means to accomplish this is to have an FAA observer inside the airplane temporarily move flight attendants to a location inside the airplane away from the vicinity of any exit which will be worked on.
(6) For those airplanes equipped with emergency assist means, the means should be installed at inactive exits as well as active exits, to avoid revealing which exits are active through the absence of the assist means.
m. Paragraph m of appendix J. The following are guidelines for the applicant to use to obtain informed consent from participants in the demonstration and still comply with the intent of paragraph m of appendix J. These guidelines are not intended to be a complete list or meet specific legal requirements. The applicant is responsible for obtaining informed consent and for complying with all applicable local, state, and federal laws and regulations regarding the protection of human beings employed in demonstrations of this nature.
(1) The applicant should seek consent under circumstances that provide the prospective participants sufficient opportunity to freely consider whether or not to participate in the demonstration. Coercion or undue influence to participate in the demonstration is not permitted.
(2) The prospective participants should be informed of the purpose of the demonstration and the expected duration of their participation. They should also be given a description of any logistical procedures to be followed before and after the demonstration.
Details of the demonstration parameters, e.g., time limits, active exit percentages, etc., should not be disclosed, but the approximate number of participants in the demonstration may be revealed.
(3) The prospective participants should be given a description of any reasonably foreseeable risks or discomforts which may be encountered in the demonstration, such as the type or probability of injury when using an escape slide. Participants may also be informed of any techniques and/or equipment that will be used to limit the discomfort or injury such as protective clothing, emergency abort procedures for the demonstration, pads around the slides, availability of restrooms, etc.
(4) Prospective participants should be informed of any direct benefits to them (e.g., pay, meals, etc.) and of benefits to society (e.g., improved safety by demonstrating the emergency evacuation capability of the airplane) that would result from their participation.
(5) Prospective participants should also be informed of any compensation and/or medical treatments that will be available if injury should occur. They should also be informed of the procedure for acquiring these services, and where further information may be obtained.
(6) Prospective participants should be informed that participation in the demonstration is voluntary, that refusal to participate will involve no penalty, and that a participant may 13
discontinue participation at any time prior to the beginning of the demonstration without penalty or loss of benefits to which the participant is otherwise entitled.
(7) Prospective participants should be informed of the potential consequences of a decision to withdraw from the demonstration at any given time and the procedures to follow for orderly termination of participation. This explanation should include the consequences of attempting to withdraw after the demonstration has started, for example, the possibility of being pushed out of the airplane if the participant stops at the exit.
(8) The prospective participants should be given the opportunity to ask questions, and be provided information on whom to contact for answers to future questions and how to withdraw from the demonstration.
(9) After participants have been fully informed, they should provide written informed consent to express their understanding and willingness to participate.
n. Paragraph n of appendix J. The passengers may be told that they are evacuating an airplane via the escape slides, if applicable, and to follow the instructions of the crew. A description of the location or operation of the exits, the conduct of the demonstration, or additional information not in the passenger briefings required by §§ 91.519, 121.333(f),
121.571(a), 121.573 (a), (c) and (d), 121.585(h) and (i), 125.327, or 135.117 should not be given.
o. Paragraph p of appendix J. In order for the active exits to be representative of all of the required emergency exits on the airplane, one exit from each pair should be used. Flightcrew exits, and exits that are not part of a pair (such as ventral exits, tail-cone exits, and exits on only one side of the fuselage) should not be used for the demonstration (even if additional passenger capacity has been granted). (Note that the MD-81 and MD-82 have a tail-cone exit and a Type I exit which is located on the left-hand side of the fuselage, aft of the wing. The FAA has certificated these two exits as an exit pair.)
p. Paragraph s of appendix J.
(1) The restriction on the acceptance rate of the stand or ramp is considered to be met, if the width of the stand or ramp is not greater than the width of the escape route required by § 25.810(c).
(2) The demonstration is complete when the last evacuee (passenger or crew) has cleared the assist means and has both feet on the ground or ramp (if provided at the off-wing exit). Typically, the entry to the ramp is coincident with the area on the wing where evacuees, led by required markings on the wing, would slide or jump to the ground.
9. Guidance for Demonstrating Compliance with § 25.803(c) Using a Combination of Analysis and Testing.
a. Regulatory Background.
(1) The preamble to Amendment 25-46 makes it clear that adequate test data are a prerequisite for using analysis instead of conducting a full-scale emergency evacuation demonstration to substantiate airplane evacuation capability. It is intended that the analysis be a conservative prediction of the results that would be achieved if a full-scale demonstration were to be conducted. As such, the assumptions used should be conservative.
(2) Full-scale demonstrations should be required when the effects on evacuation performance of configuration changes identified in paragraph 7.b cannot be substantiated by component and/or system test and analysis.
b. Technical Basis for the Analytical Approach.
(1) The analytical approach for substantiation of evacuation system capability should be based on all available, valid performance data from formal tests. The primary source of data should be from successful full-scale demonstrations. Documentation of the analysis should establish credibility by identifying elements of the evacuation system, (e.g., features of the interior arrangement, door sizes, egress assist means, and relative door locations), citing applicable tests of record involving similar or identical elements, and then applying the recorded, verifiable performance data to the new configuration in a valid manner. Data from unsuccessful full-scale demonstrations should be carefully scrutinized before being used, to ensure that the failure has not biased the data. Additionally, however, it should be verified that identified causes (equipment, configuration, or procedures) for the failed demonstrations are not included in the new configuration.
(2) Graphical representations and a detailed description of the airplane interior configuration emphasizing the emergency evacuation provisions are essential and are required for database development. A detailed configuration description should lead into and justify the use of the certification demonstrations and any other tests that are included in the database.
(3) The certification bases that apply to the specific model in question and those of other models that will be used, should be clearly stated in the analysis. The resulting implications should be thoroughly reviewed and discussed.
(4) If evacuation system certification data (from a test conducted by the applicant and witnessed by appropriate airworthiness authority personnel or representatives) with apparent relevance to the subject configuration has been purposely excluded from the analysis, the reason(s) for excluding these data should be documented and agreed to by the FAA.
(5) Any special condition, exemption, or equivalent safety finding that applies to the evacuation systems of the subject configuration, or any configuration for which data will be presented, should be discussed and referenced or included as an appendix to the analysis document.
c. The Airplane Configuration.
(1) The configuration should be described in detail. If the configuration is a derivative of an existing, previously certified configuration, the primary differences should be clearly stated in the analysis in terms of passenger capacity and evacuation capability.
(2) Features of the passenger cabin interior arrangement and evacuation system (such as aisles and cross-aisles, exit passageways, attendant assist spaces, doors and emergency hatches, etc.) significant to the analysis should be presented in the form of diagrams or formally controlled drawings in an appropriate scale. Supplemental drawing or diagrams should be provided for those features that require special attention in the analysis.
(3) The cabin arrangement and evacuation system components should be depicted and described in enough detail to establish a useful historical record. These descriptions should include, as applicable, the location, operation, and dimensions of the cabin and its features that are significant to evacuation, such as:
(a) passenger and flight attendant seats and the associated restraint systems,
(b) aisles, cross aisles, and passageways,
(c) exits, including type classification,
(d) emergency egress assist means,
(e) flight attendant assist spaces,
(f) monuments (e.g., galleys and closets), including the aspect of visual obstruction,
(g) safety equipment,
(h) lighted signs and emergency lighting, and
(i) any other cabin characteristics affecting evacuation.
(4) Features of the airplane exterior which affect evacuation (such as engines and wing flaps) should be described in detail. Exterior features and the evacuation system they affect should be presented in the form of dimensioned diagrams or formally controlled dimensioned drawings in an appropriate scale.
d. Similar Features in Previously Demonstrated Airplanes. When the configuration under consideration is a derivative model of a configuration certified by a full-scale demonstration, common features of the two configurations need to be clearly identified and discussed.
Typically, some door and assist-to-ground systems are likely to remain unchanged or be very similar in derivative models evolved from a baseline configuration. Interior features may be unchanged within complete or major parts of cabin zones.
e. Unique Features of the Configuration.
(1) Comparative drawings should be used to focus attention on configuration differences as well as similarities. The features that are unique to the configuration should receive a great deal of attention. If, for instance, a new door system is to be installed in a production model derivative, the effects of this change should be documented. Data from "similar" door systems demonstrated in other airplane models are obvious sources. To use these data, a strong case for "similarity" must exist and be developed in the analysis. For example, dimensional parameters of the unique features should match those of the demonstrated, certificated systems. Performance data from those systems could then be included in the analysis to ensure the new configuration meets the regulations.
(2) When a new installation changes some specific features of an earlier installation and, therefore, changes system performance, the change should be substantiated. Performance data from both the earlier installation and the new installation should be provided in the analysis.
f. Flight Attendant Requirements. The required minimum number of flight attendants is established by § 121.391(a). As stated in § 121.391(b), when the number of flight attendants used during a full-scale airplane evacuation demonstration for certification exceeds the minimum number stipulated by regulation, the number of flight attendants in excess of the minimum number required in § 121.391(a) must be added to the number of flight attendants required by § 121.391(a) for any seating capacity. The required number of flight attendants and their seating provisions should be indicated on an appropriate configuration diagram.
g. Interior Configuration Overview. Compliance with the requirements of §§ 25.807 through 25.815 is a prerequisite for showing compliance with § 25.803. In particular, a discussion of how the subject configuration satisfies the intent of §§ 25.807 and 25.813 is an important part of the evacuation capability analysis and should receive appropriate emphasis.
These sections define the various passenger emergency exit types, stipulate the required number and types of exits necessary to accommodate passenger seating capacities, and set forth 17
requirements for accessibility and location of exits. The analysis should directly address the issue of passenger distribution and exit capability distribution within the cabin. When physical constraints, for example, body structure, wing and engine location, prevent appropriate geometrical uniformity of exit placement, compensating factors that enhance evacuation capability should be discussed.
h. Exit Distribution Uniformity. The geometric distribution of the exits, rated capacities of the exit types provided, and passenger seating densities of the various cabin zones should be documented. The geometric distribution of exit openings is obvious when depicted to scale on a drawing. Uniform distribution of the exits relative to passenger distribution may not be immediately obvious. One means for addressing adequate exit distribution uniformity, taking passenger distribution into account, is provided in AC 25.807-1, Uniform Distribution of Exits.
i. Historical Data Foundation for the Analysis. Any analysis to determine evacuation capability of an airplane depends on the existence of applicable demonstration or test data that are formally recorded and verifiable. Applicability and validity of data are governed by evacuation system component similarity and conditions of test conduct. Conditions called out in appendix J to part 25 and § 121.291 are the best qualifiers for screening existing evacuation performance data to be applied to the subject configuration. All such data should be addressed in the analysis. Results from partial evacuation demonstrations and developmental or qualification tests should be used to fill data gaps where no full-scale evacuation demonstration precedents can be cited for elements of the subject configuration; these partial demonstrations or tests should be shown to have been conducted under appropriate conditions. In many situations the appropriate conditions are those specified in appendix J of part 25.
j. Applicable Previous Full Scale Demonstrations. Test data from full-scale certification demonstrations that are offered in support of the analysis need to be identified and described.
The date and location of the demonstration, the airplane model involved, the passenger and crew complements, and the regulation upon which the demonstration was based (part 25 and/or part
121) should be provided. The description should address the elements of paragraphs 9.c and 9.f.
If the applicability of the data is not obviously indicated by the airplane model, the reason(s) for including the demonstration should be clearly stated.
k. Applicable Subsystem Developmental, Qualification and Certification Tests.
(1) Data from tests other than full-scale emergency evacuation demonstrations that are included as data sources for the analysis, should be specifically identified and discussed.
Reasons for their inclusion should be clearly stated. As an example, deployment/inflation time data for a new slide or slide/raft could be introduced and substituted into an evacuation event sequence (time line) for a system that is otherwise identical. This would be acceptable because slide or slide/raft deployment and inflation, once initiated, is independent of further human intervention and insensitive to the test conditions of appendix J.
(2) Similarly, Latin Square testing (see appendix 4 of AC 25-17A, Transport Airplane Cabin Interiors Crashworthiness Handbook) may be used to compare the performance capability of a new escape system or systems component against the known capability of an existing system or component. Unless it is verified in other testing, however, such a comparison may need to be conducted under the test conditions of appendix J to ensure that the interface between passengers and the new system is appropriate under those conditions, for example, is the lighting of the slide sufficient to encourage evacuees to jump with minimum hesitation?
(3) Technical Standard Order C-69c requires testing under conditions that are very similar to the conditions required in appendix J. Use of these data in support of compliance with § 25.803 is acceptable when it is clear that the data generated under the TSO approval matches the data that would be generated under the type certificate. In those instances where they do not match, or it is not clear if they match, additional testing may need to be performed. The applicant should contact the FAA to determine if additional testing can be completed by the TSO approval holder (or applicant) or should involve the TC holder (or applicant). Any such proposal should be fully coordinated in advance with the FAA.
(4) A test method referred to as a “platform” or “ramp” test has also been used to assess the crew's ability to manage flow of passengers for a given interior configuration.
Appropriate test conditions and pass/fail criterion need to be discussed with and agreed to by the FAA for each new situation.
(5) The formal test reports and supplemental record (movie film or video tape) of subsystem testing should be referenced in the analysis and available for FAA review.
l. Elements of Time Required for Evacuation.
(1) A formula suited to the evacuation capability analysis task and accepted as credible and correct by the FAA has been established. It is based on an escape system time line or sequence of events that can be readily observed in film or video tape coverage of full-scale evacuation demonstrations.
(2) The total evacuation time (in seconds) through a given exit can be defined by the following expression:
TTotal =TExit Prep + TExit Flow where:
= Total evacuation time for the exit, equal to the time interval from TTotal demonstration initiation until the last evacuee arrives on the ground or onto a stand at an overwing exit as allowed by paragraph c of appendix J.
TExit Prep = Time for exit preparation, equal to the time interval from demonstration initiation until the first evacuee arrives on the ground or onto a stand at an overwing exit, including:
-- flight attendant or passenger reaction time, as appropriate,
-- exit opening, -- assist means deployment, and inflation to the point of being usable (if
applicable), -- first evacuee hesitation time (defined as the elapsed time between when the device becomes ready for use and when definite contact with the device, with motion toward the ground, has been achieved by the first evacuee), and -- time for initial evacuee to traverse to the ground (using the assist means, if applicable), or onto a stand at an overwing exit.
= Time of exit flow, equal to the time interval from first evacuee on the TExit Flow ground or onto a stand at an overwing exit to last evacuee on the ground or onto a stand at an overwing exit.
m. Database to Support the Analysis.
(1) Pertinent data values from the tests and demonstrations discussed in paragraphs 8.k and 8.l should be organized into a "database" for the analysis. The database should identify the source of each data point to the degree necessary for independent verification. For evacuation system certification demonstrations, the identifying parameters should include (as a minimum):
(a) airplane model (and operator, if applicable),
(b) date of demonstration,
(c) governing regulations, i.e., part 25 or part 121, and
(d) exit identification.
(2) When the data value used in the analysis is an interval of time between two observed events, the event times, in addition to the time intervals, should be included in the "database." The events are observable and can be verified directly, whereas the intervals are derived from the event times. A single tabulation of all events necessary to support the analysis provides a centralized database and is more easily understood and verified.
(3) Whenever a dataset contains an unusual event affecting interval time, such as an evacuee jumping out prior to full inflation of the assist means, or assist means deflating during the demonstration, those data should be adjusted as appropriate. Such adjustments should be documented in the analysis.
(4) When data values from multiple tests or demonstrations are available, it is permissible to use average performance values in the analysis. Exit flow rate data (expressed in evacuees per unit time) can be transformed to time intervals per evacuee by taking the reciprocal, then the intervals are averaged to yield the average interval per evacuee.
n. Data Presentation (Organization). Several event times in the database may need to be processed to yield the numerical values for evaluating the evacuation time of the subject configuration. Organizing the respective database values according to the time elements of the evacuation process provides a convenient means to show the data and the process. The data presentation section of an analysis should contain a subsection for each time element of the evacuation time line that requires reduction or processing of database event data, e.g., Table 1.
Table 1
DATABASE PRESENTATION EXAMPLE 757-200 CERTIFICATION DEMONSTRATION DATA Door 1L Door 2L Door 4L Exit Prep. Time (sec.) 8.1 11.8 10.0
Flow rate (epm ) 70.8 68.7 52.0
Time per evacuee (sec.) .847 .873 1.154
o. Time for Exit Preparation.
(1) The time for exit preparation needs to be determined. If part of an exit system has been upgraded or otherwise changed since the full-scale evacuation demonstration(s), it may be necessary to revise the exit preparation time from that observed in previous demonstrations before using it in the analysis. T can be determined by timed tests of the new system or by Exit Prep summing the separate elements of T Any adjustments should be fully documented. Exit Prep.
(2) Exit preparation includes opening the exit and deploying any installed assist means.
If the external assist means is an inflatable slide or slide/raft, the device is considered deployed when it exhibits the rigidity necessary to safely sustain a load (stable and fully extended) 21
although it may not necessarily be touching the ground. When the subject configuration includes the same basic exit system as formerly demonstrated, a straightforward tabulation of values applicable to that exit system should be presented. The average(s) should be shown and identified accordingly.
(3) "Hesitation time" may be defined as the interval of time between when the assist means (if required, usually a slide) is ready for use and the egress of the first evacuee. It may simply be the time necessary for the first evacuee to respond to the flight attendant's command, or it may include a reluctance to jump. The analysis should account for hesitation by measuring the time that elapses when the slide is perceived as inflated and fully extended (though not necessarily on the ground) until the first evacuee starts to descend on the slide. A suitable hesitation time may be derived by averaging all hesitation data values.
(4) Some off-wing escape systems may prompt a modification to the analysis technique to properly account for first evacuee hesitation. Overwing door opening or hatch removal may trigger a slightly delayed deployment and inflation of the off-wing inflatable. The first evacuee could emerge through the exit to the wing or wing ramp surface in advance of the off-wing slide being ready for use. Depending on available data, the evacuation capability analysis for some such systems should be based on first evacuee on the ground.
(5) After accounting for hesitation and doorway egress, the time for the first evacuee to travel from the point of contact with the slide or overwing ramp to the ground must be added to the time line. Average values, if used, should be noted. The assist means traverse time should include the on slide and on ground event times from which the traverse time interval is derived.
p. Time for Exit Flow.
(1) The period of evacuee flow through an exit system, TExit Flow, depends on flow rate and number of evacuees. Flow rates used in the analysis are those established by earlier demonstrations and tests and converted to intervals as described in paragraph 8.m.(4). T isExit Flow then derived by multiplying the number of evacuees allocated to the exit minus one (n-1) by the average interval established for each evacuee.
(2) A dependable and accurate technique to determine flow rate from film or video tape is to:
(a) select a stable point or plane of reference in the flow path field of view,
(b) record the event times for passage of first and last evacuees, thus determining the time of flow, and 22
(c) calculate the flow rate (in evacuees per unit of time) by dividing the count of evacuees minus one by the flow time.
(3) The flow time starts with the first evacuee at the reference point. The remaining evacuees pass the reference point during the flow period. One evacuee, therefore, is subtracted from the total evacuee count to determine flow rate when a fixed-point or plane of reference technique is used.
q. Evacuee Allocation to Exits. The allocation of evacuees to exits should be established and illustrated on a configuration drawing. The allocation should be consistent with the demonstrated capability of the same or similar exit systems and with the distribution of exits and passenger seating relative to the exits. The illustration should convey the substance of an emergency evacuation plan that flight attendants, and flight deck personnel (for certain part 25 applications only) work to achieve with the subject configuration. The goal of the plan is to get everyone out as soon as possible. Passenger management techniques employed in the analysis need to be substantiated by records of earlier demonstrations and/or tests.
r. Flightcrew and Flight Attendant Duties. The crew members' positions during takeoff and landing and their primary and secondary duty stations during an emergency should be indicated on a suitable configuration diagram. Their duties should be described in the analysis.
Demonstration or test data should be cited that substantiates the ability of crew members to travel to their duty stations. Procedures which would require a flight attendant to bypass an exit (other than one in the immediate vicinity of the flight attendant's seat) to get to his/her primary or secondary duty station should not be proposed.
NOTE: For applicants also seeking compliance with § 121.291, the flightcrew should have no assigned evacuation duties. Flightcrew participation is limited to part 25-only applications, where the type
certification bases precede Amendment 25-79.
s. Passenger Management.
(1) The definition of "passenger management" for purposes of this advisory circular is the directing of passengers to active exits by flight attendants after initiation of the evacuation.
The goal of passenger management is to minimize the total time for evacuation while ensuring passenger safety.
(2) To address passenger management, the applicant must show that similar flight attendant duties (see paragraph 9.r), allocation of evacuees to exits (see paragraph 9.q), and cabin configuration (see paragraph 9.c) have resulted in a successful full-scale evacuation demonstration(s) or equivalent test(s).
NOTE 1: Bypass of an active exit, when included in the analysis, must be based on bypass accomplished at an identical exit type during a full-scale demonstration on an airplane with the same number of aisles. “Bypass,” for
purposes of this advisory circular, is defined as the movement of a passenger past an active exit to get to another active exit. On a twin aisle
airplane, movement past an exit along the aisle that is not adjacent to the active exit is still regarded as bypass. The passenger management and associated crew training should also be consistent between the airplane being
analyzed and the airplane that was actually demonstrated.
NOTE 2: When exit systems are not symmetrically located or different performance characteristics have been identified for cross cabin exits, the analysis should address the more critical exit of each exit pair.
t. Total Evacuation Time Calculations.
(1) Utilizing the data, formula, and analytical techniques described above, the total evacuation time per exit as described in paragraph 9.l can be determined for the configuration.
(2) A configuration diagram, annotated with the calculated evacuation times and evacuee counts near the exits used can be used to provide a graphic summary of results. A single configuration diagram could satisfy the multiple purposes of depicting exits used, passenger and crew allocation to exits (cabin division lines) and the resulting evacuation times per exit.
u. Success Criteria.
(1) If the results of the total evacuation time calculations are less than 90 seconds, the analysis indicates that the airplane can be evacuated under the demonstration conditions established by appendix J of part 25 or section (a) of appendix D of part 121, within the time criterion contained in §§ 25.803(c) and 121.291(a), respectively. The conservatism of the analysis should be demonstrated as noted below.
(2) The applicant should then prepare an evaluation of the additional evacuation capability (time margin) of each exit that was used in the analysis.
(a) The following formula may be used to determine the available time margin for the airplane configuration being reviewed:
n Time margin = i=1 )(90 - TTotal Exit i where: