Patent Publication Number: US-2020298984-A1

Title: Airbag systems for use on aircraft

Description:
TECHNICAL FIELD 
     The present disclosure is generally related to airbags and associated systems and methods for use in aircraft and other vehicles. 
     BACKGROUND 
     Airbags can protect occupants from strike hazards in automobiles, aircraft, and other vehicles. In conventional airbag systems, a sensor detects a collision or other dynamic event of sufficient magnitude and transmits a corresponding signal to an initiation device on an inflator. The signal causes the inflator to immediately release compressed gas into the airbag, rapidly inflating the airbag in front of the occupant to cushion the impact with forward objects. 
     Some aircraft include airbags on seat belts that are secured around the occupant&#39;s waist in a conventional manner. The airbag is typically stowed on the seat belt under a flexible cover. In the event the aircraft experiences a forward impact or other significant dynamic event, the airbag rapidly inflates, displacing the cover and deploying upwardly in front of the occupant to create a cushioning barrier between the occupant and the seat back, partition, monument, or other potential strike hazard in front of the occupant. 
     Forward head excursion during a crash event can limit how close rows of passenger seats can be placed behind each other, and how close seats can be positioned relative to a partition wall or other forward strike hazard. Accordingly, it is generally desirable to reduce forward head excursion so that passenger seats can be placed closer to potential strike hazards, while still maintaining enough distance to ensure that occupants do not contact the strike hazards during a crash event. Additionally, it can also be desirable to reduce forward leg extension or flail in response to a crash event to further reduce the potential for occupant injury. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front isometric view of an occupant secured in an aircraft seat having an under-seat airbag with a leg restraint portion configured in accordance with embodiments of the present technology. 
         FIG. 2  is a partially schematic isometric view of an aircraft airbag system configured in accordance with embodiments of the present technology. 
         FIGS. 3A-3C  are a top isometric, side, and top view, respectively, of an under-seat airbag having a leg restraint portion configured in accordance with embodiments of the present technology. 
         FIGS. 4A-4C  are a series of side isometric views illustrating various stages of operation of an under-seat airbag having a leg restraint portion configured in accordance with embodiments with the present technology. 
         FIG. 5  is a front isometric view of an occupant secured in aircraft seat having an under-seat airbag with a leg restraint portion and a lap belt airbag configured in accordance with embodiments of the present technology. 
         FIG. 6  is a partially schematic isometric view of an aircraft airbag system configured in accordance with another embodiment of the present technology. 
         FIGS. 7A-7C  are a rear, front, and side view, respectively, of a lap belt airbag configured in accordance with embodiments of the present technology. 
         FIGS. 8A-8C  are a series of side views illustrating various stages of operation of an occupant restraint system having an under-seat airbag and a lap belt airbag configured in accordance with embodiments of the present technology. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure describes various embodiments of airbags and associated systems and methods for use with seats in aircraft. As described in greater detail below, and some embodiments the airbag systems can include an under-seat airbag having a first portion configured to inflate beneath the occupant&#39;s thighs and a second airbag portion configured to inflate in front of the occupant&#39;s lower legs. If the aircraft experiences a significant dynamic event (e.g., a crash event or other rapid deceleration) in which the occupant could be thrown forward against a seatback or other potential strike hazard, an electronic sensing system automatically activates an inflator to immediately release compressed gas into the under-seat airbag, causing the airbag rapidly to inflate. As the first portion of the under-seat airbag inflates, it presses upwardly on the occupant&#39;s thighs just behind the knees, driving the occupant&#39;s legs upwardly toward the occupant&#39;s torso. The upward momentum of the occupant&#39;s legs reduces the forward rotation of the occupant&#39;s torso about the lap belt, thereby reducing forward head excursion and potential injuries to the occupant. At the same time, the second airbag portion deploys outwardly between the occupant&#39;s legs and inflates laterally in front of the occupant&#39;s shins, thereby restraining forward motion and extension of the legs in response to the dynamic event. In other embodiments, the under-seat airbag can be used in combination with a lap belt airbag that inflates between the occupant&#39;s torso and thighs. In these embodiments, the upward momentum of the occupant&#39;s legs is reacted by the occupant&#39;s torso through the lap belt airbag. As a result, in some embodiments using the lap belt airbag with the under-seat airbag may reduce forward head excursion more than if the under-seat airbag was used alone. 
     Certain details are set forth in the following description and in  FIGS. 1-8C  to provide a thorough understanding of various embodiments of the present technology. In other instances, other details describing well-known structures, materials, methods and/or systems often associated with airbags, airbag inflation systems and related circuitry, seat belts, seats, etc. in aircraft and other vehicles are not shown or described in detail in the following disclosure to avoid unnecessarily obscuring the description of the various embodiments of the technology. Those of ordinary skill in the art will recognize, however, that the present technology can be practiced without one or more of the details set forth herein, or with other structures, methods, components, and so forth. 
     The terminology used below is to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain examples of embodiments of the technology. Indeed, certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this Detailed Description section. 
     The accompanying Figures depict embodiments of the present technology and are not intended to be limiting of its scope. The sizes of various depicted elements are not necessarily drawn to scale, and these various elements may be arbitrarily enlarged to improve legibility. Component details may be abstracted in the Figures to exclude details such as position of components and certain precise connections between such components when such details are unnecessary for a complete understanding of how to make and use the invention. 
     Many of the details, dimensions, angles and other features shown in the Figures are merely illustrative of particular embodiments of the disclosure. Accordingly, other embodiments can have other details, dimensions, angles and features without departing from the spirit or scope of the present invention. In addition, those of ordinary skill in the art will appreciate that further embodiments of the invention can be practiced without several of the details described below. 
     In the Figures, identical reference numbers identify identical, or at least generally similar, elements. To facilitate the discussion of any particular element, the most significant digit or digits of any reference number refers to the Figure in which that element is first introduced. For example, element  110  is first introduced and discussed with reference to  FIG. 1 . 
       FIG. 1  is a front isometric view of a seat occupant  100  (e.g., a passenger) secured in a seat  102  by a restraint system  110  having a lap seatbelt  118  and an under-seat airbag  130  configured in accordance with embodiments with the present technology. In the illustrated embodiment, the seat  102  is positioned in an aircraft seating area  104 , such as a passenger cabin of a commercial, private, or general aviation aircraft. For example, in some embodiments, the seat  102  can be at least generally similar in structure and function to a conventional seat in, for example, a first class or business class cabin of a commercial passenger aircraft. Accordingly, the seat  102  includes a back portion  103  extending upwardly from a base portion  107  in a conventional manner. The base portion  107  can include a seat pan  132  that supports a seat cushion  108  (e.g. a foam cushion) upon which the occupant  100  sits. Prior to installation on/in the seat  102 , the under-seat airbag  130  is folded and stowed within a flexible protective cover  134 . The covered under-seat airbag  130  is then installed on the seat pan  132  beneath the seat cushion  108 , or beneath at least a portion of the seat cushion  108 . In other embodiments, the under-seat airbag  130  can be integrated into the seat cushion  108  by, for example, positioning the under-seat airbag  130  in a cavity formed in the seat cushion. A gas conduit or hose  124  extends from the under-seat airbag  130  and is operably coupled in fluid communication to an airbag inflator (not shown in  FIG. 1 ). 
     In the illustrated embodiment, the lap seatbelt  118  (which can also be referred to as “two-point” restraint) includes a first web portion  112   a  and a second web portion  112   b . The web portions  112   a, b  can be at least generally similar in structure and function to conventional seatbelt webbing comprised of, for example, woven nylon, woven polyester, etc. A proximal end of the second web portion  112   b  is fixedly attached to a seat frame  106  on one side of the occupant  100  by an attachment fitting  114 , and a proximal end of the first web portion  112   a  is similarly attached to the seat frame  106  on the opposite side of the occupant  100 . A distal end of the first web portion  112   a  carries a buckle  116  that is configured to receive and releasably engage a corresponding web connector tongue (not shown in  FIG. 1 ) attached to the distal end of the second web portion  112   b . Additionally, in some embodiments a first electrical link, e.g., a first wire  126   a , and a second wire  126   b  can be routed under a cover  122  on the second web portion  112   b  to a seatbelt switch (not shown) that completes a circuit or is otherwise operable to indicate when the connector tongue on the second web portion  112   b  is properly coupled to the buckle  116 , which can be a precondition for deployment of the under-seat airbag  130 . In operation, the occupant  100  secures the seatbelt  118  around his or her waist in a conventional manner. More specifically, after sitting in the seat  102 , the occupant  100  can insert the connector tongue on the second web portion  112   b  into the buckle  116  and adjust the tension in the seatbelt  118  in a conventional manner. To release the seatbelt  118 , the occupant  100  lifts a handle on the buckle  116  or otherwise releases the connector tongue from the buckle  116  in a conventional manner. 
     In the illustrated embodiment, the seat  102  faces forward, or at least generally forward, in direction F toward the front of the aircraft. Accordingly, in this embodiment, a centerline  105  of the seat  102  extends parallel to, or at least approximately parallel to, a longitudinal axis A of the aircraft (e.g., a longitudinal axis of the aircraft fuselage). In other embodiments, the seat  102  can be positioned so that the occupant  100  faces generally forward, but with seat centerline  105  orientated at an angle (e.g., an oblique angle) relative to the longitudinal axis A. For example, in such embodiments the seat centerline  105  can be positioned at angles from about 5 degrees to about 90 degrees, or from about 10 degrees to about 45 degrees, relative to the longitudinal axis A. In other embodiments, the seat can be positioned in other orientations and/or in other settings and arrangements. Additionally, as those of ordinary skill in the art will appreciate, although only one seat  102  is illustrated in  FIG. 1 , in some embodiments additional seats can be positioned to one or both sides of the seat  102  to create a row of seats, and/or in front of or behind the seat  102  in additional rows. In other embodiments, the seat  102  can be positioned behind a partition (e.g., a closet or galley wall), or other structure. 
     In some embodiments, the airbag and restraint systems described herein can be used to protect occupants in a wide variety of vehicles, including other types of aircraft (e.g., both fixed-and-rotary-wing aircraft), land vehicles (e.g., automobiles), watercraft, etc., and with a wide variety of seating arrangements and orientations, such as center aisle seats, outer aisle seats, seats positioned directly behind other seats, monuments, walls, partitions, consoles, closets, etc., “infinite setback seats” (seats that are not positioned behind other structures), and seats in other orientations relative to, for example, the forward end of the aircraft and/or the direction F of forward travel, such as side facing seats or seats orientated at other angles relative to the longitudinal axis A of the aircraft. 
       FIG. 2  is a partially schematic isometric view of the restraint system  110  and an associated airbag deployment system  200  configured in accordance with embodiments of the present technology. As noted above with reference to  FIG. 1 , the under-seat airbag  130  can be enclosed in a flexible and protective cover  134 . The cover  134  can include can include one or more seams (e.g., tear seams) attached with stitching (e.g., “rip stitching”) that ruptures as the airbag  130  inflates so that the cover  134  does not restrain the under-seat airbag  130  as it rapidly expands. For example, the cover  134  can include a first side tear seam  234   a  and a second side tear seam  234   b . Additionally, in some embodiments the cover can also include a lateral tear seam  234   c  extending between the two side tear seams  234   a, b . The tear seams  234   a - c  can include stitching with suitable thread that is configured to break upon airbag inflation. In other embodiments, the tear seams  234   a - c  can employ adhesive or other means to hold the cover  134  together prior to inflation of the airbag  130 . In addition to the tear seams  234   a - c , the cover  134  can additionally include one or more holes  236  that extend through the cover  134  and an adjacent attachment panel  235  of the airbag  130 . The holes  236  are configured to receive one or more fasteners (e.g., rivets, screws, adhesive, etc.; not shown in  FIG. 2 ) that attach the airbag  130  and the cover  134  to the seat pan  132  ( FIG. 1 ). 
     In some embodiments, the airbag deployment system  200  includes an electronic assembly  252  (e.g., an electronic module assembly (EMA); shown schematically) and an inflator  242 . The electronic assembly  252  and/or the inflator  242  can be located, for example, under the seat  102  ( FIG. 1 ), under an adjacent seat, or in other locations suitable for connectivity to the lap belt airbag  120  and the under-seat airbag  130 . Various types of inflators known in the art can be used with the airbag systems described herein. In some embodiments, for example, the inflator  242  can include a stored gas canister that contains compressed gas (e.g., compressed air, nitrogen, argon, helium, etc.) at high pressure. The inflator  242  can include an initiator  246  (e.g., a pyrotechnic device such as a squib) operably positioned at one end and an outlet fitting  244  at the opposite end that connects the gas hose  124  to the inflator  242 . In other embodiments, other suitable inflation devices well known in the art can be use without departing from the present disclosure. Such devices can include, for example, gas generator devices that generate high pressure gas through a rapid chemical reaction of an energetic propellant, hybrid inflators, etc. Accordingly, the present disclosure is not limited to any particular type of airbag inflation device and/or system. 
     The electronic assembly  252  can be electrically connected to the inflator initiator  246  via one or more electrical links  238  (e.g., one or more wires). As discussed above, in some embodiments the restraint system  110  can include a seatbelt switch (not shown) carried on a web connector  240  which is configured to change status (e.g., close a circuit or open a circuit) when the web connector  242  is suitably engaged with the buckle  116 . The connector status as determined by the switch can be transmitted to the electronic assembly  252  via the electrical links  126   a,b  to ensure that the lap belt airbag  120  and/or the under-seat airbag  130  is only deployed when the two web portions  112   a,b  of the seatbelt web  118  are properly joined together, as this can prevent the under-seat airbag  130  from inadvertently inflating when the seatbelt  118  is not secured around the waist of a seat occupant. 
     In the illustrated embodiment, the electronic assembly  252  includes a processor  254  that receives electrical power from a power source  256  (e.g., one or more batteries, such as lithium batteries), a deployment circuit  262  that initiates the inflator  242 , and at least one crash sensor  258  (e.g., an accelerometer) that detects rapid decelerations and/or other dynamic events greater than a preset or predetermined magnitude (e.g., a deceleration greater than 15 g&#39;s). The processor  254  can include, for example, suitable processing devices for executing non-transitory instructions stored on a computer-readable medium. The crash sensor  258  can, for example, include a spring-mass damper type sensor with an inertial switch calibrated for the vehicles operating environments that initiates airbag deployment upon a predetermined level of deceleration. In other embodiments, the crash sensor  258  can include other types of sensors known in the art and/or other additional features to facilitate airbag deployment. In further embodiments, some of the components of the electronic assembly  252  described above may be omitted and/or other components may be included. Although specific circuitry is described above, those or ordinary skill in the art will recognize that a microprocessor-based system could also be used where any logical decisions are configured in software. 
     In a dynamic event above a predetermined threshold (e.g., a rapid deceleration equal to or greater than a predetermined magnitude resulting from the aircraft experiencing a collision or other significant dynamic event), the crash sensor  258  can detect the event and respond by sending a corresponding signal to the processor  254  that causes the processor  254  to send a corresponding signal to the deployment circuit  262 . Upon receiving the signal and confirmation that the connector  240  is engaged with the buckle  116 , the deployment circuit  262  applies a voltage to the inflator initiator  246  via the electrical link  238  sufficient to activate the initiator  246 , which in turn opens or otherwise causes the inflator  242  to rapidly discharge its compressed gas into the under-seat air bag  130  via the gas hose  124 . The rapid expansion of the compressed gas flowing into the under-seat airbag  130  causes the airbag  130  to rapidly expand and rupture or otherwise separate one or more of the tear seams  234   a - c , causing the cover  134  to quickly move away from the airbag  130  so that the airbag  130  can rapidly inflate to full deployment in, for example, about 40 to 55 ms. Additional details regarding deployment of the under-seat airbag  130  are provided below with reference to  FIGS. 3A-4C . 
     The airbag deployment systems described above and elsewhere herein are provided by way of examples of suitable such systems. It should be noted, however, that the various embodiments of the airbags described herein are not limited to use with the particular inflation and/or other systems described above and can also be used with other types of inflation systems without departing from the present disclosure. 
       FIG. 3A  is a top isometric view of the under-seat airbag  130  configured in accordance with embodiments of the present technology, and  FIGS. 3B and 3C  are corresponding side and top views, respectively, of the under-seat airbag  130 . Referring to  FIGS. 3A-3C  together, the under-seat airbag  130  includes a first airbag portion  370  (e.g., an under-seat portion) and a second airbag portion  372  (e.g., a leg restraint portion) which are connected to each other in fluid communication by a third airbag portion  374  (e.g., a connecting portion). In the illustrated embodiment, the first airbag portion  370  includes a bottom panel  376  and a top panel  378  that are joined together by a rear seam  382 . In the illustrated embodiment, the top and bottom panels  378  and  376 , respectively, can be generally flat and define an acute angle therebetween (e.g., an angle of from about 10 degrees to about 60 degrees, or from about 15 degrees to about 50 degrees, or about 45 degrees). A front panel  380  defines a cylindrical surface that transitions from the bottom panel  376  to the upper panel  378 . A left side panel  384   a  and a right side panel  384   b  are joined to the bottom panel  376 , the front panel  380 , and the top panel  378  along corresponding seams in a known manner to generally form the enclosure of the first airbag portion  370 . The foregoing configuration can give the first airbag portion  370  a generally tapered or triangular profile shape that, as described in greater detail below, can advantageously raise the forward edge portion of the seat cushion  108  more than the aft edge portion during inflation. 
     The third airbag portion  374  extends forwardly from the first airbag portion  370  and defines an open passage from the first airbag portion  370  to the second airbag portion  372 . In the illustrated embodiment, the third airbag portion  374  includes a top panel  360 , a bottom panel  362 , and corresponding left and right side panels  364   a  and  364   b , respectively, which are joined together by corresponding seams in a known manner to form generally concave panels around the third airbag portion  374 . 
     In some embodiments, the second airbag portion  372  can have a generally rectangular shape with rounded corners. For example, the second airbag portion  372  can include a top panel  394 , a bottom panel  396 , and a front panel  395  and left and right side panels  398   a  and  398   b , respectively, extending therebetween. Additionally, the second airbag portion  372  can include a rear panel  397  that is joined to the third airbag portion  374  to provide an open passage therebetween. In addition to the foregoing features, in some embodiments the under-seat airbag  130  can further include the attachment panel  235  that extends rearwardly from the seam  382  that joins the aft edge portion of the top panel  378  to the aft edge portion of the bottom panel  376 . The attachment panel  235  can include a plurality of the openings  236  that, as described above with reference to  FIG. 2 , receive fasteners or other means for attaching the under-seat airbag  130  and its cover  134  to the seat pan  132  as described above with reference to  FIG. 1 . 
     As shown in  FIG. 3C , in the illustrated embodiment the second airbag portion  372  has a first width W 1  and the third airbag portion  374  has a second width W 2  that is less than the first width W 1 . The difference in these widths creates a first gap  390   a  between the first airbag portion  370  and the second airbag portion  372  on a first side of the third airbag portion  374 , and a corresponding second gap  390   b  on the opposite side of the third airbag portion  374 . As described in greater detail below, the gaps  390   a,b  are shaped and sized to receive the lower leg portions of the seat occupant upon inflation of the under-seat airbag  130 . When the lower portions of the occupant&#39;s legs are positioned in the gaps  390   a,b , the second airbag portion  372  acts as a restraint that limits or reduces the forward extension/motion of the occupant&#39;s legs during a rapid deceleration or other dynamic event that would otherwise cause the occupant&#39;s legs to move rapidly forward. 
     In addition to the widths W 1  and W 2 , the second airbag potion  372  can also have a height H. By way of example only, in some embodiments the first width W 1  can be from about one foot to about three feet, or about two feet; the second width W 2  can be from about two inches to about one foot, or about six inches; and the height H can be from about four inches to about one foot, or about eight inches. In other embodiments, the first airbag portion  370 , the second airbag portion  372 , and/or the third airbag portion  374  can have other shapes and sizes without departing from the present disclosure. 
     As show in  FIG. 3A , the gas hose  124  can extend into the interior of the first airbag portion  370  via an opening  363  (e.g., a slit) in the bottom panel  376 . A distal end portion of the gas hose  124  is securely attached to the bottom panel  376  by stitching  366  or by other suitable attachments means. The distal end portion of the gas hose  124  also includes a plurality of openings  368  configured to permit high pressure gas from the inflator  242  ( FIG. 2 ) to flow rapidly into the under-seat airbag  130  via the gas hose  124 . 
     In some embodiments, the under-seat airbag  130  can include one or more tear seams  388  that prevent the airbag from fully inflating if the seat occupant is in a “brace” position. More specifically, the tear seam  388  can be a pressure sensitive seam having stitching that ruptures if the internal pressure within the airbag  130  prematurely exceeds a preset maximum as a result of the occupant&#39;s upper torso being positioned on or just above the occupant&#39;s thighs, as would be the case if the occupant was in the brace position. Preventing the under-seat airbag  130  from fully inflating when the occupant is in the brace position reduces the ability of the airbag  130  to push the occupant upwardly and out of the brace position (which is a relatively safe position in a crash event). In some embodiments, the tear seam  388  can also rupture once the under-seat airbag  130  fully inflates so that the airbag  130  quickly deflates and does not impede occupant egress away from the seating area. Additionally, in some embodiments the airbag  130  can also include one or more vents, such as one or more vent holes  392  formed in the bottom panel  376  of the first airbag portion  370 . The vent hole  392  can be appropriately shaped and sized to cause the under-seat airbag  130  to rapidly deflate after full inflation to not impede occupant egress away from the seat  102  ( FIG. 1 ). 
     The under-seat airbag  130  can be manufactured using various types of suitable airbag materials and construction techniques known to those of ordinary skill in the art. For example, in some embodiments the under-seat airbag  130  can be constructed by sewing together a plurality of panels or sheets of suitable material, such as silicon coated nylon fabric (e.g.,  315  denier silicon coated woven nylon fabric), that are cut or otherwise formed to shape in the flat pattern. The panels can be sewn together with a suitable thread using known techniques. The attachment panel  235  can be composed of one or more layers of airbag material that are not inflated during airbag deployment. In other embodiments, airbags configured in accordance with the present disclosure can be constructed using other suitable materials in construction techniques known in the art. 
       FIGS. 4A-4C  are a series of side isometric views illustrating various stages of operation of the under-seat airbag  130  in accordance with embodiments of the present technology. Referring first to  FIG. 4A , this figure illustrates the seating area  104  in a pre-airbag deployment stage with the occupant  100  seated in the seat  102  and the lap seat belt  118  properly secured around the occupant&#39;s waist. In  FIG. 4A , the seat  102  is a forward-facing seat in the seating area  104  as described above with reference to  FIG. 1 . Although not shown in  FIG. 4A , the seat  102  can be positioned behind a strike hazard, such as, for example, the seat back of the seat positioned directly in front of the seat  102 , a monument, a closet or galley wall, a partition, etc. In other embodiments, the seat  102  can be other types of seats in other positions and orientations, such as an oblique seat. 
       FIG. 4B  illustrates the seating area  104  at the initial stage of the crash or other rapid deceleration event above a preset magnitude. The rapid deceleration event causes the occupant&#39;s torso  406  to begin rotating forward about the lap belt  118 . The event also causes the airbag deployment system  200  ( FIG. 2 ) to initiate rapid inflation of the under-seat airbag  130 . As the under-seat airbag  130  inflates, the first airbag portion  370  pushes at least a forward portion of the seat cushion  108  upwardly and against the occupant&#39;s thighs  408  just behind the occupant&#39;s knees  402 . This drives the occupant&#39;s legs  404  upwardly toward the occupant&#39;s torso  406 . At the same time, the second and third airbag portions  372  and  374 , respectively, unfurl outwardly between the occupant&#39;s legs  404  from underneath the seat cushion  108  and begin to inflate. 
       FIG. 4C  illustrates the under-seat airbag  130  when it or near full inflation. As the first airbag portion  370  inflates and drives the occupant&#39;s legs  404  upwardly, the upward and/or rearward momentum of the legs  404  counteracts the forward rotation of the occupant&#39;s torso  406  (and/or is reacted by the occupant&#39;s torso  406 ), thereby reducing forward rotation of the occupant&#39;s torso  406  about the lap seat belt  118 . This reduces the forward excursion of the occupant&#39;s head  410  toward the forward strike hazard. Additionally, lifting the occupant&#39;s legs  404  in this manner reduces the tendency of the occupant  100  to translate forward on the seat pan  132 , which can further reduce forward head excursion. It is believed that reduction of forward head excursion in the foregoing manner can also reduce lumbar loads and potential related injuries to the occupant  100 . 
     As shown in  FIG. 4C , the second airbag portion  372  inflates directly in front (i.e., in direction F as shown in  FIG. 1 ) of the lower portions of the occupant&#39;s legs  404 . That is, when the second airbag portion  372  is fully inflated the lower portion of the occupant&#39;s left leg is positioned in the first gap  390   a  between the first airbag portion  370  and the second airbag portion  372 , and the lower portion of the occupant&#39;s right leg is positioned in the second gap  390   b  between the first airbag portion  370  and the second airbag portion  372 . In this configuration, the second airbag portion  372  is positioned between the occupant&#39;s legs  404  and a forward strike hazard and prevents or at least restricts forward extension and/or other movement of the legs  404  toward the strike hazard. As a result, the second airbag portion  372  can reduce the potential for occupant injuries resulting from leg flail. 
       FIG. 5  is a front isometric view of the seat occupant  100  secured in the seat  102  by a restraint system  510  configured in accordance with another embodiment of the present technology. In the illustrated embodiment, the seat  102  is positioned in the aircraft seating area  104  as described above with reference to  FIG. 1 . Accordingly, the description of the seating area  104 , the seat  102 , and/or other aspects of the seating arrangement described above with reference to  FIG. 1  can also apply to  FIG. 5 . 
     In the illustrated embodiment, the restraint system  510  includes a lap belt airbag  520  in addition to the under-seat airbag  130 . The lap belt airbag  520  is carried on a lap seatbelt  518  that is at least generally similar in structure and function to the lap seatbelt  118  described above with reference to  FIG. 1 . For example, the lap seatbelt  518  includes a first web portion  112   a  and a second web portion  112   b . In this embodiment, however, the lap belt airbag  520  is operably attached to the second web portion  112   b  of the seatbelt  518 . During assembly, the airbag  520  is folded and stowed under a flexible cover  522  which encloses the airbag  520  and can wrap around at least a portion of the second web portion  112   b . A first gas conduit or hose  524   a  extends from the airbag  520  and is operably coupled in fluid communication to an airbag inflator (not shown in  FIG. 5 ). Additionally, in some embodiments a first electrical link, e.g., a first wire  126   a , and a second wire  126   b  can be routed under the cover  522  to a seatbelt switch (not shown) that completes a circuit or is otherwise operable to indicate when the connector tongue on the second web portion  112   b  is properly coupled to the buckle  116 , which can be a precondition for deployment of the lap belt airbag  520  and the under-seat airbag  130 . As described in greater detail below, upon inflation of the lap belt airbag  520  in response to, for example, a rapid deceleration of the aircraft or other accident scenario, the airbag  520  ruptures a pressure sensitive tear seam in the cover  522  that enables the cover  522  to fall away so that the airbag  520  can fully deploy. 
     In the illustrated embodiment, a second gas hose  524   b  operably connects the under-seat airbag  130  in fluid communication with an inflator (not shown in  FIG. 5 ). As described in greater detail below with reference to  FIG. 6 , the inflator can be a single inflator that provides high pressure gas to both the under-seat airbag  130  and the lap belt airbag  520 , or a separate inflator that just provides high pressure gas to the under-seat airbag  130 . Additionally, in some embodiments the under-seat air bag  130  can be inflated by a dedicated inflator that is positioned within the under-seat airbag  130 . 
       FIG. 6  is a partially schematic isometric view of the restraint system  510  and an associated airbag deployment system  600  configured in accordance with embodiments of the present technology. In some embodiments, the airbag deployment system  600  can include an electronic assembly  252  and an inflator  242  as described above with reference to  FIG. 2 . The inflator  242  can include an initiator  246  operably positioned at one end and an outlet fitting  644  (e.g., a “T” fitting) at the opposite end that connects the first gas hose  524   a  and the second gas hose  524   b  to the inflator  242 . In other embodiments, other suitable inflation devices well known in the art can be used without departing from the present disclosure. Such devices can include, for example, gas generator devices that generate high pressure gas through a rapid chemical reaction of an energetic propellant, hybrid inflators, etc. Additionally, in other embodiments the airbag deployment system  600  can include two inflators: one for inflating the lap belt airbag  520  and the other for inflating the under-seat airbag  130 . In further embodiments, the under-seat airbag  130  can include a dedicated inflator positioned within the airbag  130 . Accordingly, the present disclosure is not limited to any particular type of airbag inflation device and/or system. 
     The electronic assembly  252  can be electrically connected to the inflator initiator  246  via one or more electrical links  238  (e.g., one or more wires). As discussed above, in some embodiments the restraint system  510  can include a seatbelt switch (not shown) carried on a web connector  240  which is configured to change status (e.g., close a circuit or open a circuit) when the web connector  242  is suitably engaged with the buckle  116 . The connector status as determined by the switch can be transmitted to the electronic assembly  252  via the electrical links  126   a,b  to ensure that the lap belt airbag  520  and the under-seat airbag  130  are only deployed when the two web portions  112   a,b  of the seatbelt web  518  are properly joined together, as this can prevent the lap belt airbag  520  and the under-seat airbag  130  from inadvertently inflating when the seatbelt  518  is not secured around the waist of a seat occupant. 
     In a dynamic event above a predetermined threshold (e.g., a rapid deceleration equal to or greater than a predetermined magnitude resulting from the aircraft experiencing a collision or other significant dynamic event), the crash sensor  258  can detect the event and respond by sending a corresponding signal to the processor  254  that causes the processor  254  to send a corresponding signal to the deployment circuit  262 . Upon receiving the signal and confirmation that the connector  240  is engaged with the buckle  116 , the deployment circuit  262  applies a voltage to the inflator initiator  246  via the electrical link  238  sufficient to activate the initiator  246 , which in turn opens or otherwise causes the inflator  242  to rapidly discharge its compressed gas into the lap belt airbag  520  and the under-seat air bag  130  via the first gas hose  524   a  and the second gas hose  524   b , respectively. The rapid expansion of the compressed gas flowing into the lap belt airbag  520  causes the airbag  520  to rapidly inflate and rupture or otherwise separate a tear seam  521  on the airbag cover  522 . This moves the cover  522  away from the lap belt airbag  520  so that the air bag  520  can quickly inflate and deploy (e.g., in about 40 to 55 milliseconds (ms)). Similarly, rapid expansion of the compressed gas flowing into the under-seat airbag  130  causes the airbag  130  to rapidly expand and rupture or otherwise separate the tear seams  234   a - c  on the cover  134 , enabling the airbag  130  to rapidly inflate to full deployment in, for example, about 40 to 55 ms. Accordingly, in some embodiments the lap belt airbag  520  and the under-seat airbag  130  can be configured to inflate and deploy simultaneously, or at least approximately simultaneously, in about 55 ms or less. Additional details regarding deployment of the lap belt airbag  520  and the under-seat airbag  130  are provided below with reference to  FIGS. 7A-8C . 
     The airbag deployment systems described above and elsewhere herein are provided by way of examples of suitable such systems. It should be noted, however, that the various embodiments of the airbags described herein are not limited to use with the particular inflation and/or other systems described above and can also be used with other types of inflation systems without departing from the present disclosure. 
       FIG. 7A  is a rear view,  FIG. 7B  is a partially cut-away front view, and  FIG. 7C  is a side view of the lap belt airbag  520  configured in accordance with embodiments of the present technology. Referring to  FIGS. 7A-7C  together, the lap belt airbag  520  is illustrated in a fully inflated and deployed configuration, and includes a rear portion or panel  774 , a bottom panel  782 , a front panel  784  and first and second side panels  780   a  and  780   b , respectively. As will be appreciated by those of ordinary skill in the art, although the foregoing portions of the lap belt airbag  520  have been described herein as “panels” for ease of reference, two or more of these panels can be formed from the same piece of material that is cut to shape in the flat pattern and folded about appropriate fold lines and/or joined together by one or more seems in a conventional manner. 
     As shown in  FIG. 7A , the second web portion  112   b  of the seatbelt  518  ( FIG. 5 ) can be sewn or otherwise attached to the rear panel  774  of the airbag  520  via stitching  770  and/or other suitable fastening means proximate to the web connector tongue  240 . As shown in  FIG. 7B , the rear panel  774  includes an opening  772  (e.g., a slit) through which the first gas hose  524   a  extends into the interior of the lap belt airbag  520 . A distal end portion of the first gas hose  524   a  is attached to the rear panel  774  by stitching  776  and/or other suitable fastening means known in the art. Additionally, the first gas hose  524   a  includes a plurality of openings  778  proximate the distal end portion that enable the high-pressure gas from the inflator  242  ( FIG. 5 ) to rapidly flow into the lap belt airbag  520  for inflation thereof. 
     In some embodiments, the lap belt airbag  520  can have a generally triangular or “wedge” profile shape when the lap belt  520  is fully inflated as shown in  FIG. 7C . More specifically, in some embodiments the rear panel  774  can extend generally perpendicular to the bottom panel  782 , and the front panel  784  can have a generally convex and curved shape that extends at an angle to connect the bottom panel  782  to the rear panel  774 . Additionally, in some embodiments, the lap belt airbag  520  can be configured so that the rear panel  774  does not extend past the chest of the seat occupant  100  ( FIG. 5 ) when fully inflated. In these embodiments, for example, the airbag  520  would not be positioned in front of the occupant&#39;s head when fully inflated. In other embodiments, the lap belt airbag can have other shapes and sizes. 
     Although not shown, in some embodiments the lap belt airbag  520  can include one or more vents (e.g., passive vents or active vents) that enable the airbag  520  to rapidly deflate after deployment. For example, in some embodiments the airbag  520  can include an opening, e.g., a hole, a tear seam that ruptures when the airbag fully inflates and reaches a sufficient internal pressure, and/or another form of “passive” vent. In other embodiments, the lap belt airbag  520  (and/or the under-seat airbag  130 ) can include an active vent as described in one or more of the patents or patent applications incorporated herein by reference. In yet other embodiments, airbag vents can be omitted. 
     The lap belt airbag  520  can be manufactured using various types of suitable airbag materials and construction techniques known to those of ordinary skill in the art. For example, in some embodiments the lap belt airbag  520  can be constructed by sewing together a plurality of panels or sheets of suitable material, such as silicon coated nylon fabric (e.g.,  315  denier silicon coated woven nylon fabric), that are cut or otherwise formed to shape in the flat pattern. The panels can be sewn together with a suitable thread using known techniques. 
       FIGS. 8A-8C  are a series of side views illustrating various stages of deployment of the under-seat airbag  130  the lap belt airbag  520  and in accordance with embodiments with the present technology. Referring first to  FIG. 8A , this Figure illustrates the airbags  130 ,  520  in a pre-deployment stage in which the occupant  100  is seated in the seat  102  with the lap seatbelt  518  properly secured around the occupant&#39;s waist. In  FIG. 8A , the seat  102  is a forward-facing seat positioned behind a strike hazard  800 . The strike hazard  800  can be virtually any type of structure typically found in front of a passenger seat or other seat (e.g., a pilot seat, flight attendant seat, etc.) on an aircraft, and can include, for example, the seatback of the seat positioned directly in front of the seat  802 , a closet or galley wall or partition, a monument, etc. Although the seat  102  is illustrated as a forward-facing seat, in other embodiments the seat  102  can be other types of seats in other orientations, such as an oblique seat as described above. 
       FIG. 8B  illustrates the seating area  104  at the initial stage of a crash or other rapid deceleration event above a preset magnitude. The rapid deceleration event causes the occupant&#39;s torso  406  to begin rotating forward about the lap belt  518 . The event also causes the airbag deployment system  600  ( FIG. 6 ) to initiate rapid inflation of the under-seat airbag  130  and the lap belt airbag  520 . As the under-seat airbag  130  inflates, the first airbag portion  370  expands and pushes the seat cushion  108  upwardly against the occupant&#39;s thighs  408  just behind the occupant&#39;s knees  402 . Additionally, the third airbag portion  374  ( FIGS. 3A-3C ) inflates forwardly from the first airbag portion  370  between the occupant&#39;s legs  404 , and the second airbag portion  372  inflates from the third airbag portion  374  and extends laterally in front of the lower portions of the occupant&#39;s legs  404 . The upward force from expansion of the first airbag portion  370  drives the occupant&#39;s legs  404  upwardly toward the occupant&#39;s torso  406 , while inflation of the second airbag portion  372  in front of the occupant&#39;s legs  404  can restrain the occupant&#39;s legs  404  and prevent or at least reduce potentially harmful forward leg flail. At the same time, the lap belt airbag  520  inflates and expands between the occupant&#39;s torso  406  and the occupant&#39;s thighs  408  as the occupant&#39;s torso  406  rotates forwardly about the lap belt  518 . As a result, the upward momentum of the legs  404  is reacted by the occupant&#39;s torso  406  through the lap belt airbag  520 , thereby reducing the forward rotation of the torso  406  and the overall forward excursion of the occupant&#39;s head  410  toward the strike hazard  800 . Additionally, lifting the occupant&#39;s legs  404  in this manner cam reduce the tendency of the occupant  100  to translate forward on the seat pan  132 , which can further reduce forward head excursion. 
       FIG. 8C  illustrates the occupant  100  at a state of maximum forward head excursion. As this view illustrates, the combination of the inflated under-seat airbag  130  and the inflated lap belt airbag  520  can substantially reduce forward head excursion and prevent the occupant&#39;s head  410  from impacting the strike hazard  800 . It is also believed that reduction of forward head excursion in this manner can reduce lumbar loads and associated injuries to the occupant  100 . Additionally, as noted above the second airbag portion  372  can concurrently reduce forward leg flail and the potential for associated injuries. 
     One advantage of reducing occupant head excursion and/or lower leg flail with the airbags  130  and/or  520  described above is that it can enable airlines to place seats closer to potential head strike hazards, while still maintaining enough distance to the head strike hazard to avoid potentially injurious contact by the occupant in the event of a crash or other rapid deceleration event. Another benefit of embodiments of the present technology is that by concealing the under-seat airbag  130  beneath the seat cushion  108  and/or integrating the airbag  130  into the seat cushion  108 , the airbag does not affect the cosmetics of the seating area  104 . Additionally, by positioning the under-seat airbag  130  beneath the cushion  108  or a potion thereof, it does not adversely affect the comfort of the seat  102  for the occupant  100 . 
     Various airbag systems and associated components are described in U.S. Pat. Nos.: 5,984;350; 6,957,828; 6,439,600; 6,535,115; 6,217,066; 7,665,761; 7,980,590; 8,439,398; 8,556,293; 8,469,397; 8,403,361; 8,818,759; 8,523,220; 9,156,558; 9,176,202; 9,352,839; 9,944,245; 9,511,866; 9,925,950; in U.S. patent application Ser. Nos.: 13/170,079; 14/468,170; 14/808,983; and in U.S. Provisional Patent Application No.: 62/495,602, each of which is incorporated herein by reference in its entirety. Indeed, any patents, patent applications and other references identified herein are incorporated herein by reference in the entirety, except for any subject matter disclaimers or disavowals, and except to the extent that the incorporated material is inconsistent with the express disclosure herein, in which case the language in this disclosure controls. Aspects of the invention can be modified, if necessary, to employ the systems, functions, and concepts of the various references described above to provide yet further implementations of the invention. 
     References throughout the foregoing description to features, advantages, or similar language do not imply that all of the features and advantages that may be realized with the present technology should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage ;  or characteristic described in connection with an embodiment is included in at least one embodiment of the present technology. Thus, discussion of the features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment. 
     Furthermore, the described features, advantages, and characteristics of the present technology may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the present technology can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the present technology. 
     Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” As used herein, the terms “connected,” “coupled,” or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word “or,” in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. 
     The teachings of the invention provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various examples described above can be combined to provide further implementations of the invention. Some alternative implementations of the invention may include not only additional elements to those implementations noted above, but also may include fewer elements. Further any specific numbers noted herein are only examples: alternative implementations may employ differing values or ranges. 
     While the above description describes various embodiments of the invention and the best mode contemplated, regardless how detailed the above text, the invention can be practiced in many ways. Details of the system may vary considerably in its specific implementation, while still being encompassed by the present disclosure. As noted above, particular terminology used when describing certain features or aspects of the invention should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the invention with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the invention to the specific examples disclosed in the specification, unless the above Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the invention encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the invention under the claims. 
     From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the various embodiments of the invention. Further, while various advantages associated with certain embodiments of the invention have been described above in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the invention. Accordingly, the invention is not limited, except as by the appended claims. 
     Although certain aspects of the invention are presented below in certain claim forms, the applicant contemplates the various aspects of the invention in any number of claim forms. Accordingly, the applicant reserves the right to pursue additional claims after filing this application to pursue such additional claim forms, in either this application or in a continuing application. 
     The following disclosure describes various embodiments of airbags and the associated systems for use with seats in aircraft. As described in greater detail below, and some embodiments