Technical Feasibility of a Wheelchair Securement Concept for Airline Travel: A Preliminary Assessment (2021)

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87 Airplane door openings and cabin spaces will need to be able to accommo- date a range of wheelchair sizes and dimensions if reasonably large numbers of people are going to be able to fly while seated in their personal wheel- chairs. Airplanes will need to have sufficient doorway and aisle clearances and clear spaces for wheelchair ingress and egress and maneuvering to and from the designated securement location. Cabins will also need sufficient room in the securement location for essential wheelchair functionality and protective space for the occupant and surrounding passengers to avoid in- jury in the event of a survivable crash impact, emergency landing, or severe turbulence. These spaces will need to exist on many airplanes in scheduled service—but particularly in high-demand markets —for people who are nonambulatory with significant disabilities to access flights to and from places they want to go. This chapter estimates these space requirements and considers them in relation to the doorways, aisles, and other features of the cabin interiors of existing airplanes in the U.S. airline fleet. As a reference for many of the estimates, the 2010 Americans with Disabilities Act (ADA) Standards for Accessible Design1 and the ADA Ac- cessibility Guidelines (ADAAG) on the standards are consulted along with wheelchair size testing and sampling data and other relevant technical lit- erature discussed in Chapter 2. Although the ADA does not apply to airline service, ADAAG’s clearance and clear space requirements were developed to ensure that buildings and other facilities can accommodate the dimensions 1 See U.S. Department of Justice. 2010. 2010 ADA Standards for Accessible Design. https:// www.ada.gov/regs2010/2010ADAStandards/2010ADAStandards_prt.pdf. 4 Airplane Space Considerations

88 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL and operating capabilities of a wide range of personal wheelchairs.2 The total space required for an in-cabin securement area will depend on the dimensions of the wheelchair plus any additional room needed for the design and opera- tion of the securement system, essential wheelchair seat functionality, and protection of the occupant and nearby passengers from objects and structure that can cause injury. To have sufficient clear space for injury protection, the dimensions of a cabin securement area were estimated in Chapter 3 to be 30 × 60 in. Also in Chapter 3, it was estimated that if two successive rows of seats are removed from a typical narrow-body airplane, then enough secure- ment space would be provided along with sufficient floor structural support to distribute the load impact by an occupied power wheelchair. While it is possible that this needed space and structural support could be obtained by removing fewer seats—which would be desirable—the assumption that two rows will be displaced is maintained in this chapter given the study’s afore- mentioned interest in determining system feasibility and not optimality. After estimating the space requirements for maneuvering and securing a wheelchair inside the cabin, these estimations are considered in relation to the door, aisle, and seating area dimensions of airplanes in the existing fleet, taking into account interior features such as closets, galleys, and lavatories. Because data on the dimensions of boarding doors are available for a wide range of airplane models, they can be compared to the minimum clear- ances that ADAAG, other relevant technical literature, and wheelchair test data indicate would be needed for most wheelchairs to enter and exit the cabin. In the case of aisle dimensions, the minimum width required by the Federal Aviation Administration (FAA) for evacuation is used as the refer- ence because it is the norm for many cabin aisles. Together, these door and aisle dimensions are likely to have a major influence on where a wheelchair securement area could be located in the cabin. Indeed, they suggest that a prospective location would be in the cabin seating area adjacent to the left forward door, which is the largest and most commonly used door for pas- senger boarding and deplaning on most airplanes at most U.S. airports. This location would enable access to sufficient space for securement with mini- mal changes to aisle widths.3 While other cabin locations may be preferable 2 Some portion of the wheelchair user population likely will not be accommodated with the dimensions in ADAAG’s standards used for this preliminary analysis. See Steinfeld, E., V. Paquet, C. D’Souza, C. Joseph, and J. Maisel. 2010. Anthropometry of Wheeled Mobility Project: Final Report. Buffalo, NY: Center for Inclusive Design and Environmental Access. As noted in Chapter 2, further analyses would consider the extent to which these dimensions account for the clearance needs of all people when using their wheelchairs for air travel. 3 In briefing the study committee, a representative of Southwest Airlines observed that a typical Boeing 737 configuration can best accommodate an occupied wheelchair in the forward portion of the aircraft (Bryan Parker, manager of interior engineering, Southwest Airlines, August 20, 2020).

AIRPLANE SPACE CONSIDERATIONS 89 or even optimal under some circumstances, depending on specific airplane interior layouts and other considerations, a front cabin location is assumed for this chapter’s limited purpose of assessing space-related technical issues and implications related to system feasibility. To help illustrate and reach some conclusions about how a front cabin securement location could be accommodated space-wise, the chapter takes a closer look at the interior of a common airplane in the airline fleet. The ADAAG-estimated clearance and clear space requirements are superim- posed on the layout of a commonly configured interior of a Boeing 737 (737) that usually boards and deplanes through the left forward door. A rationale for using a 737 for this purpose is that its cabin width is com- parable to that of the Airbus A320 (A320), which likewise usually boards and deplanes through the left forward door. Significantly, these two air- plane families are by far the most common in the U.S. airline fleet and the most heavily used for passenger travel in hundreds of high- and moderate- demand domestic markets. Depictions of the interior changes that would be needed to make room for a wheelchair securement system in the front cabin of this illustrative 737 are followed by a description of the scope of installation work entailed, including approximations of the cost incurred for the modifications when mainly considering material and labor expenses. Estimates of installation costs are given because they provide an indication of the technical complex- ity or technical effort required, which is helpful for understanding technical feasibility. Of course, a full accounting of costs from an airline economic standpoint would include the revenue implications of airplanes operating with securement systems installed, which is beyond the scope of this study. The chapter ends with a summary of key points to provide a basis for the summary assessment of the relevant technical issues, challenges, and uncertainties associated with an in-cabin wheelchair securement system concept in Chapter 5. SPACE FOR BOARDING, MANEUVERING, AND SECUREMENT There are four main space considerations for enabling a person to use a wheelchair as a seat in an airplane: (1) doorway space for entry to and egress from the airplane, (2) aisle space to turn the wheelchair between the entryway and cabin aisle, (3) aisle space for the wheelchair to be maneu- vered into and out of the securement location, and (4) room in the cabin seating area for an appropriately sized securement area. For reasons explained above, this chapter assumes that a securement location will be designated in the front cabin near the left forward boarding door. Figure 4-1a depicts a passenger backing through this door for entry to the airplane and exiting through the same door in a forward direction. A

90 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL power wheelchair is shown because its size and operation would generally require more space than a manual wheelchair. Nevertheless, both types of wheelchairs are accounted for in the ADAAG-referenced specifications for clearance and clear space. Backing through a doorway will be a complex maneuver for many users of power wheelchairs, and therefore assistance may be required. However, by backing through the forward door, the wheelchair may be more easily maneuvered into the securement area for securement in a front-facing direction, which is consistent with the direc- tion of seating in the vast majority of airline cabins. As will be discussed below, however, an ample-sized securement location that is made possible by the removal of two successive rows of seats may enable the occupant of the wheelchair to enter the airplane facing forward and then have sufficient pivot space to reorient the wheelchair for a forward-facing securement. Once through the door, the passenger is shown in Figure 4-1b maneu- vering the wheelchair through a 90-degree turn between the entryway and main cabin aisle. Figure 4-1c depicts the passenger moving the wheelchair laterally between the aisle and securement zone, and Figure 4-ld shows the wheelchair secured for flight. Having identified these occupied wheelchair movements, it is possible to estimate the room required in the cabin to enable them by referencing specifications for clearances and clear spaces. The ADAAG specifications assume that a wheelchair’s maximum width is no more than 30 in. (includ- ing armrests), and maximum length is no more than 48 in.4 As discussed in Chapter 2, testing data and other technical literature indicate that a large majority of wheelchairs have wheelbases of 26 in. or less. Measurements of 193 power wheelchair models, as cited in Chapter 2, show that 96 percent have a maximum width of 30 in. or less5 and 97 percent have a maximum length of 48 in. or less.6 The same measurement data indicate that in the vast majority of cases, wheelchair models with a maximum width of 30 in. have a wheelbase width of 26 in. or less.7 4 ADAAG specifications are based in part on wheelchair manufacturer tests; the 2010 ADA Standards for Accessible Design—which includes ADAAG—combined with the testing results for wheelchair models per Rehabilitation Engineering and Assistive Technology Society of North America (RESNA) WC-1:2019 Section 5 provide clear and harmonized guidance on spatial requirements for wheelchair use. 5 Ninety-nine percent of all tested models were found to be less than 32 in. wide. The wheelchairs that exceed 30 in. in width represent wheelchairs primarily designed for occupants weighing more than 300 lb. 6 One hundred percent of all tested models of power wheelchairs were found to be less than 51.5 in. long. 7 These measurements were available for 131 of the 193 models tested. Of those 131 models, only 5 (<4 percent) have a wheelbase width in excess of 26 in. Additional technical literature supports that the majority of wheelchair bases are 26 in. or less. See Steinfeld, E., V. Paquet, C. D’Souza, C. Joseph, and J. Maisel. 2010. Anthropometry of Wheeled Mobility Project: Final Report. Buffalo, NY: Center for Inclusive Design and Environmental Access.

AIRPLANE SPACE CONSIDERATIONS 91 FIGURE 4-1 Wheelchair maneuvers required to access a securement location at the front of the cabin near the forward boarding door: (a) maneuvering through the left forward boarding doorway (gold area indicates the space required for the wheelchair to maneuver); (b) turning between the doorway and main aisle of the passenger compartment (green indicates the space required to perform this maneu- ver); (c) maneuvering between the main aisle and securement area (yellow indicates the additional space required for this maneuver beyond the aisle); and (d) positioned in a securement location (blue indicates the securement space). (a) (c) (b) (d) In the sections that follow, these wheelchair dimensions and clear space specifications required for the maneuvers shown in Figure 4-1 are compared to the dimensions of doorways, aisles, and other cabin interior spaces of passenger airplanes. The comparisons can be complicated because differ- ent airplane families (e.g., B737, A320), airplane models within families (e.g., B737-600, -700, -800), and individual airplanes differ in their interior

92 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL layouts, dimensions, and features. However, cabin doorway dimensions, as well as overall cabin interior dimensions such as interior cabin width and height, tend to be consistent across all models in an airplane family. Like- wise, because FAA requires a minimum aisle width for evacuations, this width tends to be common across many airplanes, especially in the main (economy) cabin of the narrow-body (single-aisle) airplanes that account for the vast majority of domestic airline service. There is much more heterogene- ity, however, in other cabin interior dimensions, layouts, and features, both across models in a family and within a model, because airlines establish their own interior specifications. Even within an individual airline’s sub-fleet of a given airplane model, the interiors of the airplanes may differ. For example, an airline may operate A320s purchased or leased from multiple sources and thus have airplanes of the same model with many interior configurations. Doorway Clearances The number, size, shape, and location of doorways to the cabin of an air- plane will vary by airplane family and be influenced by factors such as the size of the airplane, certified maximum passenger capacity, and regulations governing evacuation. In general, the forward left door, usually referred to as the primary boarding door, is the largest on the airplane. Its shape, like that of other cabin doors, includes rounded corners to alleviate structural stress concentrations. The doorway opening will also have intrusions from hinges, latches, and other hardware and design features. This variability means that doorway clearances need to be measured at multiple places. Figure 4-2 shows the following two doorway clearances of interest for passage of a personal wheelchair: (A) the minimum opening width partway up the doorway when accounting for doorway intrusions, and (B) the open- ing width measured 1.5 in. above the sill (bottom) of the doorway, account- ing for the radii of the door’s two lower corners. Dimension A is relevant for determining the clearance available for the maximum overall width of a wheelchair, which is usually at the arm supports. Dimension B is relevant for determining the narrower clearance required for the wheelchair’s wheel- base as it passes through the bottom of the door opening. If the surface of the boarding bridge floor and door sill are flush, the placement of a ramp over the sill would allow the wheelbase to pass at a higher, and thus slightly wider, point in the curved bottom portion of the opening. Because ADAAG specifications call for any such rise not to exceed 1.5 in., this height is used and shown as Dimension B in Figure 4-2.8 8 The 1.5-in. lip height was chosen based on ADAAG Sub Part D Section 1192.73 as it relates to light rail vehicles and the difference in height between train station and rail cars. Note, however, that the ADAAG guidance requires newly designed rail cars and train stations to have a 0.625-in. max height difference.

AIRPLANE SPACE CONSIDERATIONS 93 As discussed above, a large majority of wheelchairs have a maximum overall width (Dimension A) of 30 in. or less, including armrests; most of these wheelchairs will have a wheelbase width (Dimension B) of 26 in. or less. The minimum clearance requirement for passing through the airplane door will therefore be determined by these dimensions, as shown in Figure 4-3. While ADAAG permits a 32-in. doorway clearance,9 a 30-in. opening could suffice for users of most wheelchairs with a maximum width of 30 in. or less when given guidance assistance.10 Because airplane cabin doors are standard for each airplane model and data on their dimensions are available, it is possible to compare these two wheelchair dimensions with the doorway dimensions of all airplane models in the U.S. fleet. The results of such a fleet-wide comparison, focusing on the largest cabin door, are provided in the addendum to this chapter and summarized in Table 4-1.11 For the purposes of this comparison, Dimen- sion A is measured as described above, while Dimension B is measured 1.5 9 Section 403.5.1 of ADAAG specifies that except as provided in 403.5.2 and 403.5.3, the clear width of walking surfaces shall be 36 in. minimum, except clear width shall be permitted to be reduced to 32 in. minimum for a length of 24 in. maximum, provided that reduced width segments are separated by segments that are 48 in. long minimum and 36 in. wide minimum. 10 A secondary operator is sometimes needed when maneuvering in a tight space. For ex- ample, in wheelchair laboratory testing, guidance assistance, which may be verbal, visual, or physical, is provided to the wheelchair occupant to help maneuver a wheelchair through tight turns for the purpose of determining the minimum size turn corridor. 11 The addendum also presents typical row seating layouts for airplane models in the U.S. commercial transport fleet. FIGURE 4-2 Boarding doorway width dimensions relevant for determining clear- ance for a personal wheelchair.

94 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL in. above the sill and assumes the presence of a ramp over the sill for the wheelchair to traverse. The doorway measurements, which are for an airplane’s largest board- ing door, indicate that more than 83 percent of airplanes have a doorway opening (at Dimension A) that is at least 32 in. wide and 93 percent have a doorway opening that is at least 30 in. wide. All of these airplanes are therefore potentially capable of accommodating wheelchairs with a maxi- mum width of 30 in. or less. However, when smaller regional jets (RJs) are excluded from the fleet data, 100 percent of the remaining airplanes, which account for most passenger enplanements (as documented in Chapter 2), have a passenger doorway opening that is at least 30 in. wide.12 Ad- ditionally, the data indicate that all airplane main boarding doorways have clearance widths when measured 1.5 in. above the sill (Dimension B) that exceed 26 in., and therefore this doorway dimension should not present 12 The Embraer family of small RJs, the EMB-134, -140, and -145, present the greatest challenges for Dimension A, having a maximum door width of 28.6 in. Embraer’s larger EJ family’s maximum door width (A) is also on the lower side, at 30 in. All other RJs in the U.S. fleet have door opening widths of at least 32 in. This analysis does not include turboprop category aircraft because they comprised less than 2 percent of the U.S. commercial transport fleet by the end of 2019. FIGURE 4-3 Minimum clearances required for a wheelchair to maneuver through a cabin boarding door (30-in. clearance partway up the door for clearance of maxi- mum wheelchair width at arm support and 26-in. clearance 1.5 in. above door sill for clearance of wheelbase).

AIRPLANE SPACE CONSIDERATIONS 95 an impediment for the large majority of wheelchairs that have a wheelbase width of 26 in. or less. In summary, measurement data for the U.S. airplane fleet suggest that main boarding doorways should not present a physical constraint for a wheelchair securement system, except potentially for the smallest RJs.13 Space for Turning Between the Doorway and Main Aisle Because the cabin main aisle runs perpendicular to the entryway, the pas- senger using a wheelchair must navigate a 90-degree turn when proceeding between the entryway and passenger seating area. ADAAG does not pro- vide space specifications for a circular turn but provides them for angle- shaped turning space with room for knee and toe clearance.14 According to the guidelines, the turn would require two perpendicular 36- × 60-in. clear spaces, configured to enable a 36-in. turning radius, as shown in Figure 4-4. Results from wheelchair testing discussed in Chapter 2 indicate that more 13 With a few exceptions, RJs have doors wide enough to accommodate power wheelchairs, but provision of RJ service with wheelchair securements would require addressing additional considerations described in Chapter 2 that include smaller cabin interiors and lack of pas- senger boarding bridges at airports to enable passengers to wheel on and off the airplane. 14 Section 304.3.2 of ADAAG specifies minimum space requirements that comply with sec- tion 306 Knee and Toe Clearance. The requirements do not assume use of the wheelchair’s extended footrest. Use of the extended footrest while turning from the doorway into the aisle may present a difficulty for some passengers. See Steinfeld, E., V. Paquet, C. D’Souza, C. Joseph, and J. Maisel. 2010. Anthropometry of Wheeled Mobility Project: Final Report. Buf- falo, NY: Center for Inclusive Design and Environmental Access. However, the 30- × 60-in. minimum space for the wheelchair securement area is sufficient for use of the extended footrest when maneuvering into the wheelchair space and while the wheelchair is secured. TABLE 4-1 Percent of U.S. Passenger Airplane Fleet (on December 1, 2019) with Sufficient Boarding Door Clearances to Accommodate an ADAAG-Aligned Wheelchair, with Clearances Measured at Points (A and B) Defined in Figure 4-2 Doorway Opening Clearance Width Percent of Total Jet Fleet Percent of Jet Fleet Excluding EMB-135, -140, -145a ≥32 in. at A 83.2 88.9 ≥30 in. at A 93.6 100.0 ≥28 in. at B 93.6 100.0 ≥26 in. at B 100.0 100.0 NOTE: The measurements are for an airplane’s largest door that could be used for boarding. a EMBs comprised only about 6.4 percent of the U.S. fleet in 2019.

96 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL than 83 percent of wheelchairs (of 185 power wheelchair models tested) can execute a right-angle turn if provided this amount of space. When the tested dimension was increased from 36 to 38 in., 95 percent could execute the maneuver; however, ADAAG’s 36- × 60-in. space is referenced here. The availability of a clear space for turning between the entryway and cabin seating area will differ by airplane and interior layout. Many airplanes will have a closet adjacent to the main boarding door, but some will have other features such as a windscreen, galley, or passenger seating that will affect the decision about where to locate the securement area and the best door to be used for wheelchair boarding and deplaning. Regardless of where the wheelchair enters and exits the airplane, it is likely that one or more of these stationary features would impede the turn and need to be resized or removed from the area, as discussed more below. However, as noted earlier, a cabin interior dimension that can be characterized with more confidence is the width of the aisle between the seats in the main pas- senger cabin. To facilitate evacuation, FAA regulations (14 CFR § 25.815) require the passenger aisle to be at least 15 in. wide from floor level up to a distance of 25 in., above which the aisle must be at least 20 in. wide. As a result, many narrow-body airplanes will have aisle widths of 15 in. at floor level in order to maximize the space available for passenger seats. This aisle width would be a physical constraint for an airline considering a wheel- chair securement area located far from the boarding door because nearly all personal wheelchairs will have a wider wheelbase (outer tread width) that would require widening the aisle by removing revenue-producing seats. FIGURE 4-4 Space required to turn between the entryway and main aisle.

AIRPLANE SPACE CONSIDERATIONS 97 A wheelchair securement area located near the turn from the boarding door is likely to require fewer changes to the interior, including aisle widths. Partly for this reason, Figure 4-4 depicts a turn between the commonly used left forward boarding doorway and a securement location at the head of the main aisle in the passenger cabin. Assuming that two successive rows of seats will be displaced for the creation of a securement location with suf- ficient structural capacity (see Chapter 3), the liberated space would mean that no additional aisle widening would be required for a wheelchair to maneuver to a securement area located close to the turn. While Figure 4-4 shows two rows of economy seating (i.e., three-place seat assemblies) being displaced, the same number of rows would need to be displaced within first class seating (i.e., two-place seat assemblies). Space for Maneuvering into Position and Securement Once in the aisle and adjacent to the securement location, the wheelchair will need to move forward and backward in small increments to maneuver laterally into position. A 30- × 48-in. occupied wheelchair would need at least that much rectangular area plus some additional length to execute the back- and-forth movements. However, it was established in Chapter 315 that the securement location would require a 30- × 60-in. space and the removal of two successive rows of seats for distributing the wheelchair load to the floor and primary airplane structure. The available aisle width and the space af- forded by the removal of two seat assemblies should provide sufficient room for lateral movement into the securement space, as shown in Figure 4-5. This 30- × 60-in. area would provide space for the occupant of the wheelchair to make seat adjustments for medical pressure relief (e.g., tilt, recline, and leg elevate), without encroaching on surrounding passenger space.16 The 30- × 60-in. securement area footprint is shown in Figure 4-6. Because the distance available for seats between the window and aisle varies, it is not clear where the wheelchair would be positioned within the larger space (approximately 60 × 60 in.) afforded by the removal of two seat assemblies, but it would probably be centered between the two seat tracks (for even load distribution) and thus far enough from the aisle not to encroach on the 15-in. minimum aisle width. Assuming the 30- × 60-in. securement space is situated in a 60- × 60-in. square, this space plus the 15-in. wide aisle should provide sufficient room, as determined from ADAAG, for an occupied power wheelchair to enter 15 Per Section 305 of ADAAG. 16 See Steinfeld, E., V. Paquet, C. D’Souza, C. Joseph, and J. Maisel. 2010. Anthropometry of Wheeled Mobility Project: Final Report. Buffalo, NY: Center for Inclusive Design and Environmental Access.

98 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL FIGURE 4-5 Space required to maneuver between the aisle and securement loca- tion (15-in. aisle width depicted at floor level). FIGURE 4-6 Space required for the securement area.

AIRPLANE SPACE CONSIDERATIONS 99 the airplane moving forward and to execute a 180-degree turnaround to place the wheelchair in a front-facing position in the securement zone, as shown in Figure 4-7. As discussed in Chapter 2, only 1 percent of tested wheelchairs require a pivot width that exceeds 60 in.17 17 Note that Figures 4-1 through 4-7 show a person with knees flexed at 90 degrees; as noted in Chapter 2, further analyses would consider the extent to which the dimensions shown ac- count for the clearance needs of all people, including those who may not be able to flex their knees when using their wheelchairs. FIGURE 4-7 Minimum space required in the securement area and adjacent aisle to turn the wheelchair around to a front-facing securement position after entering facing forward.

100 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL Importantly, it is reasonable to expect that for some people who use wheelchairs, the execution of some or all of the maneuvers depicted above may require direction and guidance from a traveling companion or cus- tomer service agent. SPACE REQUIREMENTS IN RELATION TO AN EXISTING AIRPLANE INTERIOR The following sections illustrate the types of changes to an existing airplane interior that may be needed to meet the clearance and clear space minimums estimated above using a commonly configured 737 interior. A 737 airplane was selected because its family, along with the A320 family, dominate the U.S. airline industry. A strong case can be made that for any wheelchair securement concept to succeed, it would need to be applicable to these two airplane fami- lies, which together account for about two-thirds of scheduled airline enplane- ments, nearly half of all departures, and more than half of all airplanes in the airline fleet (see Table 4-2). Because the width of the 737’s cabin interior (139 in.) is narrower than that of the A320 (146 in.), the interior dimensions that are depicted for the 737 would not be identical to those of the slightly larger A320 but still highly comparable. A left forward boarding door scenario is assumed for most of the illustrations but an alternative securement location situated close to a left rear boarding door is also shown to convey some of the interior space challenges that this scenario would present. Some important caveats are required before illustrating with a 737 interior. While the illustrations show how the removal of passenger seats and changes in the locations and dimensions of monuments (e.g., closets, galleys, lavatories) may be required in those cabin areas where the wheel- chair will need to maneuver and be secured, they cannot show the potential ramifications of these changes and relocations for the cabin as a whole. TABLE 4-2 Share of Total U.S. Passenger Enplanements and Scheduled Departures in the Boeing 737 and the Airbus A320 Airplane Families and Their Share of the Airline Fleet, July–December 2019 Airplane Family Percent of Enplanements Percent of Departures Percent of Airplanes in Airline Fleet Boeing 737 37.8 30.7 29.1 Airbus A320 28 21.6 22.3 All Other 34.2 47.7 48.6 NOTES: Boeing 737 models include 737-800, 737-700/700LR/Max7, and 737-900. Airbus A320 models include A319, A320-100/200, A320/200n, A321, and A321-200n. SOURCE: U.S. Department of Transportation, Bureau of Transportation Statistics, including T100 data.

AIRPLANE SPACE CONSIDERATIONS 101 These impacts would depend on the specific interior features requiring modification and/or relocation. If major monuments such as lavatories and galleys need to be relocated, some can only be moved to specific install- ment zones in the cabin due to constraints such as the airplane’s structural capacity, electrical and plumbing system designs, weight and balance con- siderations, the location of flight and environmental control systems, and requirements for emergency exit. In most cases it would not be possible to move a galley or lavatory without making major changes to the cabin interior. Furthermore, even seemingly modest changes to an interior can have implications on a host of other passenger safety and comfort features, such as lighted signage, access to oxygen dispensing units, overhead lighting and passenger service units (PSUs), and emergency lighting. While potential impacts on such features are noted later, their locations are not shown in the illustrations. The 737 illustrations assume that a storage closet is located near the forward boarding door where the wheelchair would enter and exit the air- plane. Closets are commonly located near this boarding door for cabin ser- vice items and to allow passengers to stow garment bags and certain other carry-on items; hence, the assumption that a closet would be located at the entryway can be considered reasonble, albeit not universally applicable. If required, the resizing or removal of a closet is likely to be less problematic than the redesign, removal, or relocation of a major monument. The de- pictions show economy class seating in the front of the cabin; however, as noted earlier, two rows of seats would need to be removed regardless of whether the seating is economy, business, or first class. Finally, a depiction of boarding through the rear door is provided as a supplemental illustra- tion. Because the rear of the airplane invariably houses lavatories and a galley, the presence of these stationary features will affect this scenario’s suitability for a securement area. Use of the rear door for general boarding and deplaning could also present logistical challenges, as will be noted. A full interior of a 737 with first class seating is shown in Figure 4-8. The major monument locations are depicted, including a storage closet just aft of the forward boarding door and galleys and lavatories near both the forward and rear doors. FIGURE 4-8 Boeing 737 interior layout with first class seating.

102 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL Clearing the Doorway Figure 4-9 shows the clearance widths of the forward left boarding door of a 737. As established above, all airplanes in the U.S. airline fleet, except some RJs,18 have main boarding doorway clearances capable of accom- modating a wheelchair with the following dimensions: 30 in. wide with a 26-in.-wide wheelbase. The width of the 737 left forward boarding door- way measures 34 in. at its maximum (partway up the door frame) and 27.3 in. at 1.5 in. above the door sill. One would not expect that any changes to this doorway would be required for a personal wheelchair to pass through it, but a ramp may be required to clear the doorway’s bottom corners. Turning Between the Entryway and Aisle ADAAG specifies two perpendicular 36- × 60-in. clear spaces after the en- tryway to allow for a 36-in. turning radius for maneuvering a wheelchair through the 90-degree turn.19 The aft-side closet adjacent to the doorway of the 737’s interior shown in Figure 4-10 would need to be reduced in size or removed to make room for this turning corridor. 18 These include EMB-135, -140, and -145; turboprops were not evaluated due to the small percentage currently in use in the United States. 19 As mentioned in Chapter 2, while this report uses the ADAAG dimensions for reference, further analyses would consider the extent to which these dimensions account for the clearance needs of all people when using their wheelchairs with regard to issues such as toe positioning beyond foot support surface. FIGURE 4-9 Forward boarding door clearances, Boeing 737.

AIRPLANE SPACE CONSIDERATIONS 103 Maneuvering Laterally Between the Aisle and Securement Area Figure 4-11 shows the space requirements for a wheelchair maneuvering between the securement area and aisle. Because the requisite 30- × 60-in. corridor would already require the removal of two successive rows of seats, no additional modifications would be required apart from adding the securement system and its load distribution mechanism. The wheelchair securement location is assumed to be centered between the two seat tracks about 30 in. from the left edge of the aisle, ensuring that the wheelchair will not encroach into this protected space (see Figure 4-12). FIGURE 4-10 Turning corridor clearance between the entryway and aisle, Boeing 737. FIGURE 4-11 Space for a wheelchair maneuvering laterally between the aisle and securement area, Boeing 737.

104 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL The vertical space by the window in this depicted wheelchair secure- ment area, which is the space with the lowest headroom clearance on the 737, is 62.2 in. from the lower surface of the standard overhead bin to the floor.20 This vertical space should provide sufficient headroom for a person seated in a wheelchair considering that the sitting height for the 99th per- centile male is 40.3 in.21 Likewise, the A320 family has 63.1 in. of vertical space under the overhead bin.22 Rear Entry and Securement A rear, or aft, entry and securement in the 737 is illustrated in Figure 4-13 based on the same space requirements depicted in the figures above. The same data on airplane doors as referenced above (although not shown) in- dicate that the rear door of a 737 would be wide enough (30 in.) for most wheelchairs to pass but with less clearance than when passing through the forward door. The passenger in the wheelchair could enter facing forward but may need to back out for egress (unless there is sufficient room to turn around in the securement zone), which would be particularly chal- lenging due to the tighter doorway clearance. In this example, a lavatory 20 Boeing. 2005. Boeing 737 Ground Handling Manual, pp. 66–67. 21 This measurement was provided to the committee by Beneficial Design, Inc., from wheel- chair testing described in Chapter 2. 22 This information was provided to the committee via correspondence with Pierre-Antoine Senes, Airbus, March 2021. FIGURE 4-12 Space requirements for a wheelchair securement area near the for- ward loading door, Boeing 737.

AIRPLANE SPACE CONSIDERATIONS 105 would need to be removed or reduced in size, if even possible. Removal of the lavatory would also require relocating two flight attendant seats to a nearby structure other than the lavatory’s outer wall. Figure 4-13 conveys some of the potential disadvantages of a securement location in this area of the cabin, which is a common location for lavatories that are space constrained and not good candidates for relocation or size reduc- tion. Removal of one lavatory from a narrow-body airplane, whether at the rear or elsewhere in the airplane, could make the passenger-to-lavatory ratio too high. The aft of the airplane is also a common location for gal- leys. Removal of a galley or loss of galley space could affect in-flight meal service and storage space for carts and emergency equipment. In addition, boarding and deplaning through a rear door could also present logisti- cal challenges at airports that have mostly fixed or stationary boarding bridges that are designed to access the forward doors of a narrow-body airplane.23 If there is a need or preference to board all passengers (includ- ing passengers using wheelchairs) through the same door, general boarding and deplaning through a rear door would also keep high-fare, first class passengers who are usually seated at the front of the cabin from being able to deplane quickly ahead of other passengers, which may be undesirable from an airline’s perspective. 23 National Academies of Sciences, Engineering, and Medicine. 2013. Apron Planning and Design Guidebook. Washington, DC: The National Academies Press, p. 26. https://www.nap. edu/catalog/22460. FIGURE 4-13 Space requirements for a wheelchair securement area near the rear door, Boeing 737.

106 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL CHANGES REQUIRED TO AIRPLANE INTERIORS The illustrations above indicate that modifications to an airplane cabin interior would be needed to accommodate the space required for wheel- chair securement systems. All of the interior changes that would be needed, however, are not depicted in the illustrations because even modest revisions to an interior will require changes to systems and equipment other than monuments and seats. Implementing these changes will require investments in design and engineering to ensure that the renovated interior will operate seamlessly and reliably, while also meeting FAA certification criteria, inte- grating products from multiple manufacturers, and satisfying the airline’s business model requirements. As a result, modifying or upgrading systems in a cabin interior, or introducing new equipment and systems, can be a complex optimization challenge. As noted earlier, the fixed physical constraints of an interior modifica- tion can include the fuselage-limited cabin width, structural load limits, location of doors, availability of electric power and plumbing, and location of vital flight control systems. In addition, compliance with safety require- ments is essential, including those associated with the following: • Emergency oxygen, • Escape path lighting, • Signage visibility (fasten seat belt/no smoking), • Life vest accessibility, • Cabin crew visibility of the entire aisle and at least 50 percent of seating, • Delethalization of interior objects (no sharp edges or loose parts that could injure passengers during an incident or evacuation), • Smoke and toxicity (burn) certification of interior components, • Emergency decompression flow (to prevent floor structural collapse in the event of a rapid decompression), • Electrical load analysis, and • Electro-magnetic interference for electrical systems and components. All changes to the interior that will affect any of the items in this list, which is not exhaustive, must be evaluated against regulatory criteria. Due to the need to balance these many different and often competing requirements and interests, the design of an airplane interior tends to be an iterative process that requires many tradeoffs. For example, an airline may consider more than 100 different regulatory-compliant interior layouts for a single desired seating configuration intended to maximize the revenue potential for a given route structure and customer base. Any change, even modest, to an airplane interior (e.g., seat count, seat positions, seat model

AIRPLANE SPACE CONSIDERATIONS 107 or manufacturer, movement of a galley or lavatory) can alter the balance and require the airline to obtain a Supplemental Type Certificate from FAA to show airworthiness. Changing the interior of an existing airplane, of course, will also re- quire investments in the specific modifications that could be accompanied by revenue losses when the plane is out of service, thereby motivating in- terior modifications for wheelchair securement installations during periods of scheduled maintenance or other alternations. To illustrate some of the potential cost implications, a listing is provided of the kinds of interior systems and features likely to be impacted if a 737 interior were to be reno- vated to meet the space requirements depicted in Figures 4-9 through 4-12. The list of systems and features that would need to be removed during the modification includes the following: • Forward closet aft of the boarding door, • Bulkhead mounted in-flight entertainment (IFE) screens and litera- ture pockets from the aft wall of the closet, • First two rows of seating on one side, • IFE cabling between the first two rows of seating and the rest of the seat column, • Overhead seat row placarding, • Overhead PSU from above the area where the first two rows of seats were removed, and • Carpet from under the area of the first two rows of removed seats. The removal of these systems and features would need to be followed by the addition and reconfiguration of the following systems and features. Note that the next list assumes that a load-distributing pallet will be used to attach the wheelchair securement installation to the seat tracks, as described in Chapter 3. The securement system itself is not listed. • Downsized closet; • Rewiring of closet lighting as required; • IFE screens and literature pocket on the aft wall of the new closet (this is the video screen for the occupant of the wheelchair); • New entryway aisle flooring to compensate for reduced-size closet; • New standard width front row economy class seat (at first seat row location behind the securement system) with in-arm tray tables and in-arm IFE screens; • Sidewall mounted literature pocket for new front row passenger seats on side (for this new front row economy class seat); • Modified emergency escape path lighting system to accommodate removal of first two rows of seats;

108 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL • Reconfigured overhead PSU for comfort and service functions to relocate PSU and drop-down oxygen location commensurate with wheelchair tiedown location (PSU filler panels as required);24 • PSU for wheelchair passenger to accommodate remote control of the panel functions and installation of remote control for reading light and attendant call functionality; • Seat row placarding kit; • Modified and reprogrammed cabin management system for seat reconfigurations (required due to changing the number of rows of seats in the airplane, as it affects the flight attendant call button); • IFE seat to seat wiring; • IFE software, as the number of IFE screens on the airplane has changed with the removal of the six passenger places (two rows of passenger seats); and • Wheelchair securement pallet (including stowage for emergency life vest, and remote controls for PSU functionality), carpet kit for pallet installation, and installation of the securement system. The total cost of these interior changes can be approximated for the purpose of providing insight into the potential technical complexity and scale of a renovation project. Individual airplane modifications also will en- tail many non-recurring engineering (NRE), design, and certification costs that are not shown because they can vary widely from airplane to airplane and thus cannot be generalized. It may or may not be possible to amortize these NRE and certification costs across multiple airplanes, depending on the heterogeneity of the airline fleet and whether multiple similar interiors will be modified. Changes to an airplane’s interior that pertain to its type of certificate will require new investments in NRE that could substantially increase the cost of the modification, perhaps by multiples of the actual cost of kit materials and installation labor. Table 4-3 shows the price ranges for kit materials that would be needed to make the modifications listed above for cabins with economy and first class seating configurations. The ranges represent approximations based on committee members’ subject matter expertise and knowledge of interior renovation projects of comparable scale and complexity. Assuming the ren- ovations could be made in 1 to 3 days during an airplane’s scheduled main- tenance, installation labor would be on the order of $5,000 to $15,000. It merits emphasizing again that this range for a single airplane does not include NRE and FAA certification costs, which will vary by airplane and depend on whether the costs can be amortized over multiple airplanes. 24 On the 737 family, the reading light and attendant call buttons are located in the over- head PSU and normally require a passenger reaching up to the PSU to activate them. There are modifications that can be made for the 737 family that will allow a passenger to activate them with a remote control.

AIRPLANE SPACE CONSIDERATIONS 109 TABLE 4-3 Approximations of Price Ranges for Products (Kit Materials) Needed to Make Referenced Modifications for Cabins with First Class and Economy Class Seating Economy Class Price Range Reduced-size closet $30,000 $36,000 Securement pallet $5,000 $10,000 Standard front row triple-seat assembly with in-seat IFE $20,000 $30,000 Escape path lighting modification kit $2,000 $3,000 Flooring modification kit $1,000 $2,000 PSU filler panels $800 $1,200 Seat row placard kit $50 $250 Remote control kit for wheelchair passenger PSU $1,200 $1,800 Cabin management system software reprogramming $500 $1,200 IFE modification kit $2,300 $3,500 Sidewall mounted lit pockets $1,600 $2,400 Sidewall mounted life vest for wheelchair passenger $1,200 $1,800 Total $65,650 $93,150 First/Business Class Price Range Reduced-size closet $30,000 $36,000 Securement pallet $5,000 $10,000 Business class seat with in-arm video $28,000 $40,000 Escape path lighting modification kit $2,000 $3,000 Flooring modification kit $1,000 $2,000 PSU filler panels $800 $1,200 Seat row placard kit $50 $250 Remote control kit for wheelchair passenger PSU $1,200 $1,800 Cabin management system software reprogramming $500 $1,200 IFE modification kit $2,300 $3,500 Sidewall mounted lit pockets $1,600 $2,400 Sidewall mounted life vest for wheelchair passenger $1,200 $1,800 Total $73,650 $103,150

110 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL SUMMARY OF KEY POINTS Airplane cabin interiors will need sufficient room for the clearances and clear spaces required for a majority of personal wheelchairs of common types and sizes to (1) enter and egress through the boarding doorway, (2) move within the cabin to and from the securement location, (3) maneuver into and out of the securement location, and (4) be positioned for secure- ment. ADAAG, other technical specifications, and wheelchair measure- ment data provide reference wheelchair dimensions of 30 × 48 in. with a maximum 26-in. wheelbase. These guidelines and reference dimensions can be used for estimating the clearance and clear space minimums needed for wheelchairs to maneuver through an airplane doorway and in the cabin. Airplanes usually have multiple doors that can be used for passenger boarding, but the left forward door is used most often and is typically the largest door to the cabin. Based on the reference wheelchair dimensions, airplane doorway clearances will need to be at least 30 in. wide partway up the door opening and 26 in. wide at 1.5 in. above the sill to accommodate a range of personal wheelchairs. Measurements of all jet airplane models in the U.S. airline fleet indicate that more than 93 percent have doorway openings that will accommodate wheelchairs, including 100 percent when excluding some smaller RJs. Door measurements for the U.S. passenger air- line fleet suggest that airplane boarding doorways should not be a physical constraint to in-cabin wheelchair securement systems being installed widely. The variability in cabin interior layouts and dimensions precludes de- finitive determinations about where a wheelchair securement place would best be located in any given airplane’s cabin. Nevertheless, a securement area for a forward-facing wheelchair located near the forward boarding door is likely to require fewer changes to the interior than a placement in other locations, where lavatories and galleys are more likely to be impacted. By backing into the doorway and through the turn to the main aisle, the wheelchair can be positioned for securement in a forward-facing direction, which is consistent with the orientation of most airline passenger seating. Alternatively, the space provided by the removal of two rows of seats in the securement zone, plus available aisle width, should provide sufficient room for a wheelchair entering facing forward to turn around for a forward- facing securement. Maneuvering the wheelchair between the entryway and the main aisle of the airplane will require a 90-degree turn within two perpendicular 36- × 60-in. clear spaces to allow for a minimum 36-in. turning radius. A wheel- chair securement at the front of the passenger cabin should not require further widening of the aisle, assuming that at least two successive rows of seats are removed to provide space for the securement. The securement space will provide part of the clear space required for maneuvering the

AIRPLANE SPACE CONSIDERATIONS 111 wheelchair laterally between the aisle and securement position. A rectangu- lar securement area of 30 × 60 in. would provide the clear space required for these lateral movements, the front and rear clearance needed for pas- senger safety, access to two seat tracks for distributing the load imparted by the occupied wheelchair, and room for essential wheelchair position adjustments (e.g., tilt, recline, and leg elevate) during flight. The ability of the more than 6,000 U.S. passenger airplanes to pro- vide the cabin space required for wheelchair securement systems, and the interior changes that would be required for each, is difficult to assess due to variability in interiors across and within airplane families, models, and fleets. Nevertheless, because the airplanes in the 737 family and the comparably-sized A320 family are by far the most prevalent airplanes in the U.S. airline fleet, the ability of sufficient numbers of these ubiquitous airplanes to accommodate wheelchair securement would be critical for assuring adequate service availability and coverage. Comparisons of clear- ance and clear space minimums for a wheelchair securement system with the dimensions of a commonly configured 737 interior illustrate how the cabin space required for wheelchair securement can be created with interior changes that would likely be of moderate technical complexity.

112 WHEELCHAIR SECUREMENT CONCEPT FOR AIRLINE TRAVEL ADDENDUM Doorway Dimensions and Typical Row Layouts for Airplane Models in the U.S. Commercial Transport Fleet Airplane Type Airplane Count Percent of U.S. Fleet Maximum Width of Largest Door (in.) Door Width at 1.5 in. Lip (in.) Floor Width Inside Corner Radii (in.) Typical Y Class Seat Layout Airplane Types with at Least One Column of Triple Seats EMB-135 27 0.42 28.6 26.4 20.5 1 × 2 EMB-140 58 0.90 28.6 26.4 20.5 1 × 2 EMB-145 328 5.09 28.6 26.4 20.5 1 × 2 E175 43 0.67 30 28.3 22.1 2 × 2 ERJ170-100 62 0.96 30 28.3 22.1 2 × 2 ERJ175 483 7.50 30 28.3 22.1 2 × 2 ERJ190 80 1.24 30 28.3 22.1 2 × 2 A319-100 355 5.51 32 30.4 24.3 3 × 3 X A320-200 537 8.34 32 30.4 24.3 3 × 3 X A320neo 116 1.80 32 30.4 24.3 3 × 3 X A321-200 429 6.66 32 30.4 24.3 3 × 3 X A220 28 0.43 32 32 32 2 × 3 X MD-90-30 65 1.01 34 30 22 2 × 3 X MD-88 90 1.40 34 30 22 2 × 3 X 757-200 204 3.17 33 26.3 17 3 × 3 X 757-300 37 0.57 33 26.3 17 3 × 3 X 767-200 9 0.14 33 36.7 28 2 × 3 × 2 X 717-200 111 1.72 34 30 22 2 × 3 X 737 MAX 72 1.12 34 27.3 18 3 × 3 X 737-200 2 0.03 34 27.3 18 3 × 3 X 737CL 26 0.40 34 27.3 18 3 × 3 X 737NG 1,774 27.55 34 27.3 18 3 × 3 X 747-400 9 0.14 34 3 × 4 × 3 X CRJ100 8 0.12 38.2 35.3 27 2 × 2 CRJ200 384 5.96 38.2 35.3 27 2 × 2 CRJ700 265 4.12 38.2 35.3 27 2 × 2 CRJ900 291 4.52 38.2 35.3 27 2 × 2

AIRPLANE SPACE CONSIDERATIONS 113 767-300 131 2.03 42 36.7 28 2 × 3 × 2 X 767-400 37 0.57 42 36.7 28 2 × 3 × 2 X 777-200 141 2.19 35 32.3 28 3 × 3 × 3 X 777-300 40 0.62 35 32.3 28 3 × 3 × 3 X 787-10 11 0.17 35 32.3 28 3 × 3 × 3 X A330-200 50 0.78 42 40.3 34.1 2 × 4 × 2 X A330-300 40 0.62 42 40.3 34.1 2 × 4 × 2 X A330neo 4 0.06 42 40.3 34.1 2 × 4 × 2 X 787-8 32 0.50 35 32.3 28 3 × 3 × 3 X 787-9 47 0.73 35 32.3 28 3 × 3 × 3 X A350-900 13 0.20 42.3 37.9 29.8 3 × 3 × 3 X SOURCES: Committee analysis and data obtained from personal communications with Andre Cavalca, Embraer; Stephen Kalhok, MHIRJ Aviation Group; Andrew Keleher, Boeing; and Pierre-Antoine Senes, Airbus.