Airbus S.A.S. v. Firepass Corporation ( 2019 )


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  •   United States Court of Appeals
    for the Federal Circuit
    ______________________
    AIRBUS S.A.S.,
    Appellant
    v.
    FIREPASS CORPORATION,
    Appellee
    ______________________
    2019-1803
    ______________________
    Appeal from the United States Patent and Trademark
    Office, Patent Trial and Appeal Board in No. 95/001,555.
    ______________________
    Decided: November 8, 2019
    ______________________
    MARK ALEXANDER CHAPMAN, Hunton Andrews Kurth
    LLP, New York, NY, argued for appellant. Also repre-
    sented by CLIFFORD ULRICH.
    ROGER THOMPSON, The Law Offices of Roger S. Thomp-
    son, New York, NY, argued for appellee.
    ______________________
    Before LOURIE, MOORE, and STOLL, Circuit Judges.
    STOLL, Circuit Judge.
    Airbus S.A.S. appeals the Patent Trial and Appeal
    Board’s reversal of the patent examiner’s rejection of
    2                                  AIRBUS S.A.S. v. FIREPASS CORP.
    certain new claims presented by patent owner Firepass
    Corporation in an inter partes reexamination of U.S. Pa-
    tent No. 6,418,752. Airbus challenges the Board’s finding
    that an asserted prior art reference fails to qualify as rele-
    vant prior art because it is not analogous to the claimed
    invention of the ’752 patent. We hold that the Board erred
    in its analogous art analysis by declining to consider record
    evidence relied on by Airbus to demonstrate the knowledge
    and perspective of a person of ordinary skill in the art at
    the time of the invention. We therefore vacate the Board’s
    reversal of the examiner’s rejection and remand for recon-
    sideration in view of this additional evidence.
    BACKGROUND
    This inter partes reexamination returns from a prior
    appeal in which we vacated the Board’s decision dismissing
    Airbus’s cross-appeal for lack of jurisdiction and remanded
    to the Board to consider Airbus’s challenge to certain newly
    presented claims. See generally Airbus S.A.S. v. Firepass
    Corp., 
    793 F.3d 1376
     (Fed. Cir. 2015). Airbus now appeals
    the Board’s reversal of the examiner’s rejection of those
    newly presented claims on remand.
    I
    The ’752 patent discloses a fire prevention and sup-
    pression system that prevents and extinguishes fires using
    breathable air instead of water, foam, or toxic chemicals—
    each of which can present risks to personnel or electronic
    equipment. See ’752 patent col. 1 ll. 47–65, col. 2 ll. 41–64.
    The invention is based on the inventor’s alleged discovery
    that a low-oxygen (“hypoxic”) but normal pressure
    (“normbaric”) atmosphere inhibits fire ignition and com-
    bustion, yet remains breathable for humans. See 
    id.
    at col. 4 l. 60–col. 5 l. 25. More specifically, the ’752 patent
    explains that, if one reduces the atmospheric concentration
    of oxygen from its natural level of 20.94% to about 16.2%
    or slightly lower while adding nitrogen to maintain the
    same air pressure, fires are suppressed while humans can
    AIRBUS S.A.S. v. FIREPASS CORP.                                3
    continue to breathe. 
    Id.
     at col. 6 ll. 21–67. The specifica-
    tion applies this principle to various fire-preventative and
    fire-suppressive enclosed facilities, from computer rooms
    and automobile tunnels to military vehicles and spacecraft.
    See 
    id.
     at col. 10 l. 55–col. 22 l. 45. These enclosed facilities
    can utilize a “hypoxic generator” that produces hypoxic air
    by altering the composition of the surrounding ambient air.
    See 
    id.
     at col. 9 l. 36–col. 10 l. 21. But “[a]ny oxygen extrac-
    tion device, such as a nitrogen generator or an oxygen con-
    centrator can be used instead of a hypoxic generator” with
    certain adaptations. See 
    id.
     at col. 10 ll. 22–54.
    Claim 91, the only independent claim at issue on ap-
    peal, is illustrative of the claimed invention:
    91. A system for providing breathable fire-preven-
    tive and fire suppressive atmosphere in enclosed
    human-occupied spaces, said system comprising:
    an enclosing structure having an internal environ-
    ment therein containing a gas mixture which is
    lower in oxygen content than air outside said struc-
    ture, and an entry communicating with said inter-
    nal environment;
    an oxygen-extraction device having a filter, an inlet
    taking in an intake gas mixture and first and sec-
    ond outlets, said oxygen-extraction device being a
    nitrogen generator, said first outlet transmitting a
    first gas mixture having a higher oxygen content
    than the intake gas mixture and said second outlet
    transmitting a second gas mixture having a lower
    oxygen content than the intake gas mixture;
    said second outlet communicating with said inter-
    nal environment and transmitting said second mix-
    ture into said internal environment so that said
    second mixture mixes with the atmosphere in said
    internal environment;
    4                              AIRBUS S.A.S. v. FIREPASS CORP.
    said first outlet transmitting said first mixture to a
    location where it does not mix with said atmos-
    phere in said internal environment;
    said internal environment selectively communi-
    cating with the outside atmosphere and emitting
    excessive internal gas mixture into the outside at-
    mosphere;
    said intake gas mixture being ambient air taken in
    from the external atmosphere outside said internal
    environment with a reduced humidity; and
    a computer control for regulating the oxygen con-
    tent in said internal environment.
    J.A. 77.
    II
    The asserted prior art reference at issue on appeal,
    
    U.S. Patent No. 5,799,652
     (Kotliar), is an earlier-issued pa-
    tent with the same named inventor as the ’752 patent. 1 Ko-
    tliar discloses equipment for providing hypoxic air in an
    enclosed area for the purposes of athletic training or ther-
    apy. Kotliar col. 1 ll. 14–29. The disclosed invention can
    simulate low-oxygen mountain air for training at different
    elevations. See 
    id.
     at col. 1 ll. 50–53, col. 2 ll. 5–10. The
    disclosed system uses a “hypoxicator” that, similar to the
    “hypoxic generator” of the ’752 patent, produces hypoxic air
    by altering the composition of the surrounding ambient air.
    See 
    id.
     at col. 3 ll. 18–47. The Kotliar specification dis-
    closes a preferred oxygen range of 7% to 15%, which is
    1    The ’752 patent expressly acknowledges that its in-
    vention is “related in part” to Kotliar—at least in a subject
    matter sense. ’752 patent col. 1 ll. 14–15; see also 
    id.
    at col. 4 ll. 60–62 (referencing “Hypoxic Room System”
    manufactured by Hypoxico Inc., the named assignee of Ko-
    tliar).
    AIRBUS S.A.S. v. FIREPASS CORP.                              5
    below the 16.2% flame-preventative threshold disclosed in
    the ’752 patent. See 
    id.
     at col. 4 ll. 21–24. Kotliar explains
    that its system could be applied to “any closed room or
    structure,” 
    id.
     at col. 8 ll. 14–25, and also envisions its ap-
    plication to the passenger compartment of an automobile,
    see 
    id.
     at col. 8 l. 34–col. 9 l. 39.
    III
    Beyond Kotliar, the examiner considered other prior
    art references as part of Airbus’s validity challenges to
    other claims of the ’752 patent. 2 Four of these references
    are relevant on appeal.
    Gustafsson 3 is a study focused on “human performance
    during [a] prolonged stay in normobaric hypoxia, a so-
    called ‘fire retardant atmosphere.’” J.A. 1860. The refer-
    ence explains that “[r]educed oxygen levels have . . . been
    discussed for fire prevention in closed spaces, such as sub-
    marines, computer rooms, store rooms, archives, or muse-
    ums.” 
    Id.
     It further explains that “if humans are to work
    and live in localities where hypoxic atmospheres are used,
    a balance must be struck between the level of fire preven-
    tion achieved and the effect of hypoxia on human perfor-
    mance.” 
    Id.
     After surveying the literature, Gustafsson
    discloses the results of a human performance experiment
    in which the subjects were exposed to different levels of
    normobaric hypoxia for periods extending up to ten days.
    2   Firepass did not appeal the examiner’s rejection of
    these other claims to the Board. Instead, Firepass canceled
    claims 29–90 and 95–100 prior to its latest appeal to the
    Board.
    3   Christina Gustafsson et al., Effects of Normobaric
    Hypoxic Confinement on Visual and Motor Performance,
    68 AVIATION, SPACE, & ENVTL. MED. 985 (1997).
    6                              AIRBUS S.A.S. v. FIREPASS CORP.
    The 1167 Report 4 is a report from the U.S. Navy that
    examines the medical hazards of four types of flame-sup-
    pressant atmospheres for “sealed chambers.” J.A. 1872.
    One of the disclosed “modifications of air that will suppress
    or extinguish flames” is the partial replacement of oxygen
    by nitrogen, or “N2 Dilution.” J.A. 1871–72. Another is
    “N2 Pressurization,” the addition of compressed nitrogen to
    air. 
    Id.
     After surveying the literature, the 1167 Report
    discloses the results of six experiments performed to assess
    the effect of hypoxia at normobaric pressure on health and
    mental function over time. The 1167 Report endorses the
    use of N2 Dilution to suppress flames aboard patrolling
    submarines. It further suggests that N2 Dilution and
    N2 Pressurization “may be combined at minimal hazard to
    the crews serving aboard patrolling submarines.”
    J.A. 1871.
    Luria, 5 which shares an author with the 1167 Report,
    similarly explores the effect of “nitrogen-based, fire-retard-
    ant atmospheres” on human performance, particularly vis-
    ual sensitivity. J.A. 2669–70. The reference discloses
    various experiments and concludes that the results support
    a strategy of reducing oxygen concentration to suppress
    fires.
    
    U.S. Patent No. 3,893,514
     (Carhart) is titled “Suppres-
    sion of Fires in Confined Places by Pressurization.” Car-
    hart explains that “[i]t is well known to those skilled in the
    art that fires are supported by oxygen and that by using
    some means to deplete the surrounding area of oxygen or
    lowering the percent of oxygen the fire will be suppressed.”
    4 D.R. KNIGHT, NAVAL SUBMARINE MED. RESEARCH
    LAB., REPORT NO. 1167, THE MEDICAL HAZARDS OF FLAME-
    SUPPRESSANT ATMOSPHERES (1991).
    5 D.R. Knight et al., Effect of Nitrogen-Based, Fire-Re-
    tardant Atmospheres on Visual and Mental Performance,
    UNDERWATER AND HYPERBARIC PHYSIOLOGY IX (1987).
    AIRBUS S.A.S. v. FIREPASS CORP.                              7
    Carhart col. 1 ll. 17–20. Carhart also explains that it is
    well-known that “[s]uppression of fires in open spaces and
    in confined spaces require[s] different efforts to extinguish
    the fire.” 
    Id.
     at col. 1 ll. 20–22. And, “the presence of ma-
    chinery, electrical equipment, and more importantly the
    presence of human beings within the area of a fire requires
    special considerations for the type of extinguishant used.”
    
    Id.
     at col. 1 ll. 22–26.
    Carhart is specifically “directed to a system and
    method of adding nitrogen under pressure to a confined
    area including a habitable atmosphere to suppress a fire
    without any deleterious effects on humans within the envi-
    ronment in which the fire is suppressed.” 
    Id.
     at col. 1
    ll. 61–65. An object of the disclosed invention is to “sup-
    press a fire in a closed chamber while maintaining an en-
    vironment suitable for human activity.” 
    Id.
     at col. 2 ll. 6–
    8. The areas of interest include “confined storage areas
    such as a room-type safe or machine room that require a
    controlled environment,” but Carhart’s system “may be
    used for any controlled habitable environment which is ei-
    ther an enclosed area or an area which may be closed by
    closing of a door or window.” 
    Id.
     at col. 2 ll. 56–64; see also
    
    id.
     at col. 4 ll. 27–32 (similar).
    IV
    On remand from this court, the examiner rejected
    newly presented claims 91–94 as obvious over Kotliar in
    view of other prior art. The examiner also rejected other
    claims as obvious over various combinations of Kotliar with
    each of Gustafsson, the 1167 Report, Luria, and Carhart.
    Before the examiner, Firepass disputed whether Kotliar
    disclosed certain claim limitations and a motivation to
    combine the asserted prior art. But Firepass did not dis-
    pute Kotliar’s status as analogous art to the ’752 patent.
    Accordingly, the examiner evaluated neither Kotliar’s sta-
    tus as analogous art, nor the disclosures of Gustafsson, the
    1167 Report, Luria, and Carhart as background references
    8                              AIRBUS S.A.S. v. FIREPASS CORP.
    establishing the knowledge and perspective of a person of
    ordinary skill in the art at the time of the invention.
    Firepass appealed the examiner’s rejection of
    claims 91–94 to the Board. Firepass then argued for the
    first time that Kotliar is not analogous art to the claimed
    invention of the ’752 patent, and is therefore not relevant
    prior art for the purposes of obviousness. The examiner did
    not respond to this new argument in his answer, resting
    instead on his prior rejections. For its part, Airbus did not
    argue in its respondent brief that Firepass had waived this
    new argument; instead, Airbus addressed the issue on the
    merits. In relevant part, Airbus relied on Gustafsson, the
    1167 Report, Luria, and Carhart to argue that “[i]t was
    well-known before the alleged invention of the ’752 patent
    that a reduced oxygen atmosphere could be both breath-
    able and fire suppressive.” J.A. 4297; see also J.A. 4298–
    99.
    The Board found that Kotliar was not analogous art
    and reversed the examiner’s rejections of claims 91–94.
    The Board explained that “[t]here is no articulated rational
    underpinning that sufficiently links the problem of fire
    suppression/prevention confronting the inventor” of the
    ’752 patent to the invention disclosed in Kotliar, “which is
    directed to human therapy, wellness, and physical train-
    ing.” J.A. 13. In doing so, the Board declined to consider
    Airbus’s argument that “breathable fire suppressive envi-
    ronments [were] well-known in the art” because none of the
    four references relied on by Airbus was specifically used to
    support the examiner’s rejection of claims 91–94. 
    Id.
    Airbus appeals the Board’s reversal of the examiner’s
    rejection.    We have jurisdiction under 
    28 U.S.C. § 1295
    (a)(4)(A).
    DISCUSSION
    On appeal, Airbus challenges the Board’s finding that
    the Kotliar reference is not analogous to the claimed
    AIRBUS S.A.S. v. FIREPASS CORP.                             9
    invention of the ’752 patent. 6 A reference qualifies as prior
    art for an obviousness determination only when it is anal-
    ogous to the claimed invention. In re Klein, 
    647 F.3d 1343
    ,
    1348 (Fed. Cir. 2011). Whether a reference qualifies as
    analogous prior art is a question of fact that we review for
    substantial evidence. In re Bigio, 
    381 F.3d 1320
    , 1324
    (Fed. Cir. 2004).
    Two separate tests define the scope of analogous prior
    art: “(1) whether the art is from the same field of endeavor,
    regardless of the problem addressed and, (2) if the refer-
    ence is not within the field of the inventor’s endeavor,
    whether the reference still is reasonably pertinent to the
    particular problem with which the inventor is involved.”
    
    Id. at 1325
     (first citing In re Deminski, 
    796 F.2d 436
    , 442
    (Fed. Cir. 1986); then citing In re Wood, 
    599 F.2d 1032
    ,
    1036 (C.C.P.A. 1979)). The Board held that Kotliar does
    not qualify as prior art under either of these two tests. For
    the reasons that follow, we hold that the Board’s “field of
    endeavor” determination is supported by substantial evi-
    dence, but the Board erred in its “reasonably pertinent” de-
    termination because the Board declined to consider record
    evidence advanced by Airbus to demonstrate the
    knowledge and perspective of a person of ordinary skill in
    the art at the time of the invention.
    I
    We first address the Board’s application of the field of
    endeavor test. In resolving questions of obviousness, “we
    6   On appeal, Airbus also challenges the Board’s var-
    ious determinations regarding waiver, including the
    Board’s determination that Firepass did not waive its non-
    analogous art argument when it failed to raise that argu-
    ment before the examiner. See generally Appellant’s
    Br. 59–69. We have considered Airbus’s arguments, but we
    find no reversible error in the Board’s waiver analysis.
    10                            AIRBUS S.A.S. v. FIREPASS CORP.
    presume full knowledge by the inventor of all the prior art
    in the field of his endeavor.” Wood, 599 F.2d at 1036. To
    determine the applicable field of endeavor, the factfinder
    must consider “explanations of the invention’s subject mat-
    ter in the patent application, including the embodiments,
    function, and structure of the claimed invention.” Bigio,
    
    381 F.3d at 1325
     (first citing Wood, 599 F.2d at 1036; then
    citing Deminski, 
    796 F.2d at 442
    ). In Wood, for example,
    our predecessor court determined the field of endeavor
    based on an express disclosure in the Background of the
    Invention section of the applicant’s specification. 599 F.2d
    at 1036.
    While the disclosure of the references is the primary
    focus, this court has also instructed that the factfinder
    must consider each reference’s disclosure in view of the
    “the reality of the circumstances,” Bigio, 
    381 F.3d at 1326
    (quoting In re Oetiker, 
    977 F.2d 1443
    , 1447 (Fed. Cir.
    1992)), and “weigh those circumstances from the vantage
    point of the common sense likely to be exerted by one of
    ordinary skill in the art in assessing the scope of the en-
    deavor,” 
    id.
     In Deminski, for example, this court found that
    the challenged prior art references were in the same field
    of endeavor because they disclosed pumps and compressors
    that had “essentially the same function and structure” as
    the claimed piston devices. 
    796 F.2d at 442
    .
    The Board’s finding under the field of endeavor test is
    supported by substantial evidence. The Board looked to
    the written description and claims of the ’752 patent and
    Kotliar to determine the field of endeavor for each refer-
    ence. Based on the ’752 patent’s disclosure, the Board
    found that the field of endeavor for the ’752 patent is “de-
    vices and methods for fire prevention/suppression.” J.A. 8.
    For support, the Board relied on the preamble of claim 1 of
    the ’752 patent, which recites “[a] system for providing
    breathable fire-preventive and fire suppressive atmos-
    phere in enclosed human-occupied spaces.” 
    Id.
     (emphasis
    AIRBUS S.A.S. v. FIREPASS CORP.                           11
    omitted) (quoting ’752 patent col. 22 ll. 48–50). 7 The Board
    also cited the title of the ’752 patent, which similarly re-
    cites “Hypoxic Fire Prevention and Fire Suppression Sys-
    tems and Breathable Fire Extinguishing Compositions for
    Human Occupied Environments.” 
    Id.
     The Board further
    observed (without any citation) that “the Specification of
    the ’752 Patent is indisputably directed to the problem of
    fire prevention and fire suppression.” 
    Id.
     Turning to Ko-
    tliar, the Board found that the applicable field of endeavor
    is “human therapy, wellness, and physical training.” 
    Id.
    For support, the Board quoted the title, “Hypoxic Room
    System and Equipment for Hypoxic Training and Therapy
    at Standard Atmospheric Pressure,” along with several
    passages from the Field of the Invention section of Kotliar.
    
    Id.
     (quoting Kotliar Title, col. 1 ll. 14–29). The Board also
    emphasized that the term “fire” does not appear at all in
    Kotliar. 
    Id.
     Thus, the Board concluded that “Kotliar can-
    not reasonably be said to be within the field of endeavor” of
    the ’752 patent. 
    Id.
     We cannot say that the Board’s finding
    is unreasonable.
    Airbus contends that the Board’s determination is not
    supported by substantial evidence because the Board failed
    to identify adequate support in the specification and
    claims. Airbus emphasizes that the Board only cited the
    title of the ’752 patent and the preamble of a single claim
    not at issue on appeal. While we agree that the Board’s
    analysis could have been more developed, we disagree with
    Airbus’s contention. A finding is supported by substantial
    evidence if a “‘reasonable mind might accept’ a particular
    evidentiary record as ‘adequate to support a conclusion.’”
    Dickinson v. Zurko, 
    527 U.S. 150
    , 162 (1999) (quoting Con-
    sol. Edison Co. of N.Y. v. NLRB, 
    305 U.S. 197
    , 229 (1938)).
    In view of the Board’s factual findings that (1) the
    7  The challenged claims 91–94 include the same pre-
    amble as claim 1.
    12                             AIRBUS S.A.S. v. FIREPASS CORP.
    challenged claims are expressly directed to a fire-preven-
    tive and fire-suppressive system, and (2) Kotliar does not
    even recite the word “fire” once throughout the entirety of
    its disclosure, a reasonable mind could conclude that the
    ’752 patent and Kotliar are directed to different fields of
    endeavor—especially for a “common sense” inquiry like
    this. Bigio, 
    381 F.3d at 1326
    .
    Airbus does not point to any express disclosure in ei-
    ther reference that directly contradicts the Board’s conclu-
    sion. 8 Instead, Airbus argues that these two references
    share the same function, “producing breathable hypoxic air
    that is fire-preventative and fire-suppressive for a human-
    occupied enclosure,” and the same structure, “a system
    that includes an oxygen-extraction device (a nitrogen gen-
    erator).” Appellant’s Br. 40. In support of this argument,
    Airbus relies in part on the references that the Board de-
    clined to consider—Gustafsson, the 1167 Report, Luria,
    and Carhart—to argue that “a POSA would have known
    and appreciated that the breathable hypoxic air produced
    by Kotliar is fire-preventative and fire-suppressive, even
    though Kotliar does not state this.” 
    Id.
     at 41–42 (emphasis
    added).
    We agree that the knowledge of a person of ordinary
    skill in the art, as demonstrated by particular prior art ref-
    erences, could be relevant to establishing the scope of the
    field of endeavor. As discussed in greater detail in the fol-
    lowing section, the Board should have considered Gus-
    tafsson, the 1167 Report, Luria, and Carhart as record
    evidence relevant to the knowledge and perspective of an
    ordinarily skilled artisan at the time of the invention. But
    to the extent the Board failed to do so here, its error is
    8    Indeed, the specification of each reference includes
    a “Field of the Invention” section that distinctly describes
    each applicable field of endeavor. Compare ’752 patent
    col. 1 ll. 16–45, with Kotliar col. 1 ll. 13–29.
    AIRBUS S.A.S. v. FIREPASS CORP.                           13
    harmless. Even taking these additional prior art refer-
    ences into account, we are not persuaded that a reasonable
    factfinder could conclude that a person of ordinary skill
    would understand that Kotliar—a reference that is ex-
    pressly directed to exercise equipment and fails to mention
    the word “fire” even a single time—falls within the field of
    fire prevention and suppression. Such a conclusion would
    not only defy the plain text of Kotliar, it would also defy
    “common sense” and the “reality of the circumstances” that
    a factfinder must consider in determining the field of en-
    deavor. Bigio, 
    381 F.3d at 1326
     (quoting Oetiker, 
    977 F.2d at 1447
    ). We therefore conclude that the Board’s determi-
    nation under the field of endeavor test is supported by sub-
    stantial evidence.
    II
    We next address the Board’s application of the reason-
    ably pertinent test. Outside of an inventor’s field of en-
    deavor, “we only presume knowledge from those arts
    reasonably pertinent to the particular problem with which
    the inventor was involved.” Wood, 599 F.2d at 1036 (citing
    In re Antle, 
    444 F.2d 1168
    , 1171–72 (C.C.P.A. 1971)). This
    rule reflects the “reality of the circumstances” that “an in-
    ventor could not possibly be aware of every teaching in
    every art.” 
    Id.
     Indeed, “[t]he pertinence of the reference as
    a source of solution to the inventor’s problem must be rec-
    ognizable with the foresight of a person of ordinary skill,
    not with the hindsight of the inventor’s successful achieve-
    ment.” Sci. Plastic Prods., Inc. v. Biotage AB, 
    766 F.3d 1355
    , 1359 (Fed. Cir. 2014) (first citing Oetiker, 
    977 F.2d at 1447
    ; then citing KSR Int’l Co. v. Teleflex Inc., 
    550 U.S. 398
    , 421 (2007)).
    Accordingly, a reference outside an inventor’s field of
    endeavor is “reasonably pertinent” only if its subject mat-
    ter “logically would have commended itself to an inventor’s
    attention in considering his problem.” In re Clay, 
    966 F.2d 656
    , 659 (Fed. Cir. 1992). In other words, references are
    14                            AIRBUS S.A.S. v. FIREPASS CORP.
    “reasonably pertinent” only if “a person of ordinary skill
    would reasonably have consulted those references and ap-
    plied their teachings in seeking a solution to the problem
    that the inventor was attempting to solve.” In re GPAC
    Inc., 
    57 F.3d 1573
    , 1578 (Fed. Cir. 1995) (quoting Heidel-
    berger Druckmaschinen v. Hantscho Commercial, 
    21 F.3d 1068
    , 1071 (Fed. Cir. 1994)). In GPAC, for example, we
    found that a reference disclosing an equilibrium air door
    was reasonably pertinent to a patent directed to asbestos
    removal because they both addressed the same problem of
    “maintaining a pressurized environment while allowing for
    human ingress and egress.” 
    Id.
     at 1578–79. But if the
    problems addressed are substantially different, then the
    references are not analogous. See Clay, 
    966 F.2d at
    659–
    60. In Clay, for example, we held that a reference that
    sought to recover oil from rock was not reasonably perti-
    nent to the problem of “preventing loss of stored product to
    tank dead volume while preventing contamination of such
    product”—even though both references generally related to
    the petroleum industry. 
    Id.
    In finding that Kotliar is not reasonably pertinent to
    the problem of fire prevention and suppression, the Board
    accurately observed that the examiner’s rejection did not
    “provide or explain the requisite correlation” between the
    problems addressed by Kotliar and the ’752 patent. J.A. 9.
    But in doing so, the Board also expressly declined to con-
    sider multiple references in the record that Airbus asserted
    would establish the necessary link. Specifically, Airbus ar-
    gued that four prior art references in the record—Gus-
    tafsson, the 1167 Report, Luria, and Carhart—establish
    that the use of normbaric hypoxic atmospheres in enclosed
    environments was well-known in the art of fire prevention
    and suppression at the time of the invention. Thus, accord-
    ing to Airbus, an ordinarily skilled artisan seeking to ad-
    dress the problem identified by the ’752 patent would
    reasonably have consulted references relating to enclosed
    hypoxic environments, such as Kotliar. While the four
    AIRBUS S.A.S. v. FIREPASS CORP.                              15
    references were considered by the examiner as part of other
    obviousness combinations, the Board refused to consider
    them because they were “not cited or applied in the pro-
    posed rejection, and consequently, not fully addressed by
    the Examiner or the Patent Owner as to their rele-
    vancy . . . as to claim 91.” J.A. 13.
    We hold that the Board erred by refusing to consider
    these references in support of the reasonably pertinent
    test. Because a “reasonably pertinent” reference is one
    that an ordinarily skilled artisan would reasonably have
    consulted in seeking a solution to the problem that the in-
    ventor was attempting to solve, the reasonably pertinent
    inquiry is inextricably tied to the knowledge and perspec-
    tive of a person of ordinary skill in the art at the time of the
    invention. For example, the reasonably pertinent inquiry
    may consider where an ordinarily skilled artisan would
    reasonably look, and what that person would reasonably
    search for, in seeking to address the problem confronted by
    the inventor. In order to determine whether a reference is
    “reasonably pertinent,” then, a reasonable factfinder
    should consider record evidence cited by the parties to
    demonstrate the knowledge and perspective of a person of
    ordinary skill in the art at the time of the invention.
    The Gustafsson, the 1167 Report, Luria, and Carhart
    prior art references are relevant to the question of whether
    a person of ordinary skill in the art of fire prevention and
    suppression would have reasonably consulted references
    relating to normbaric hypoxic atmospheres to address the
    problem of preventing and suppressing fires in enclosed en-
    vironments. See Background § III, supra. These references
    could lead a reasonable factfinder to conclude that an ordi-
    narily skilled artisan in the field of fire prevention and sup-
    pression would have looked to Kotliar for its disclosure of a
    hypoxic room, even though Kotliar itself is outside the field
    of endeavor.
    16                              AIRBUS S.A.S. v. FIREPASS CORP.
    This court’s opinion in Randall Manufacturing v. Rea,
    
    733 F.3d 1355
     (Fed. Cir. 2013), is instructive. Randall sim-
    ilarly involved an inter partes reexamination in which the
    Board reversed the examiner’s obviousness rejection of sev-
    eral patent claims. 733 F.3d at 1356. The Board rejected
    the challenger’s proposed four-reference combination due
    to a lack of motivation to combine. See id. at 1361. As here,
    the challenger pointed to a host of other references that the
    examiner had considered over the course of the examina-
    tion—including some that had been the basis for rejecting
    other claims—as background evidence establishing what a
    person of ordinary skill would have known at the relevant
    time. See id. at 1360. But the Board refused to consider
    these background references, and instead limited its re-
    view to the content of the four references in the asserted
    combination. See id. at 1361.
    We vacated and remanded for the Board to consider the
    background references. See id. at 1363–64. We explained
    that KSR requires consideration of the “background
    knowledge possessed by a person having ordinary skill in
    the art,” and that our pre-KSR decisions consistently re-
    quire consideration of common knowledge and common
    sense. Id. at 1362 (quoting KSR, 
    550 U.S. at 418
    ). We em-
    phasized that “documentary evidence consisting of prior
    art in the area” is “perhaps the most reliable” form of evi-
    dence of what an ordinarily skilled artisan would have
    known. 
    Id.
     at 1362–63. As we explained:
    By narrowly focusing on the four prior-art refer-
    ences cited by the Examiner and ignoring the addi-
    tional record evidence [the challenger] cited to
    demonstrate the knowledge and perspective of one
    of ordinary skill in the art, the Board failed to ac-
    count for critical background information that
    could easily explain why an ordinarily skilled arti-
    san would have been motivated to combine or mod-
    ify the cited references to arrive at the claimed
    inventions.
    AIRBUS S.A.S. v. FIREPASS CORP.                              17
    Id. at 1362.
    Here, the Board distinguished Randall on the ground
    that Randall concerned motivation to combine, not analo-
    gous art. We do not agree that this is a meaningful basis
    for distinction in this context. Motivation to combine and
    the scope of analogous art are both factual inquiries under-
    pinning an obviousness determination that take into ac-
    count the knowledge and perspective of an ordinarily
    skilled artisan. We therefore hold that the principles of
    Randall should apply here with equal effect: an analysis of
    whether an asserted reference is analogous art should take
    into account any relevant evidence in the record cited by
    the parties to demonstrate the knowledge and perspective
    of a person of ordinary skill in the art. We accordingly va-
    cate the Board’s reversal of the examiner’s rejection and
    remand for the Board to reconsider its analogous art deter-
    mination.
    CONCLUSION
    We have considered the parties’ other arguments, and
    we do not find them persuasive. For the foregoing reasons,
    we vacate the Board’s reversal of the examiner’s rejection
    and remand to the Board to consider whether Kotliar is
    analogous art in view of the four prior art references relied
    on by Airbus to demonstrate the knowledge and perspec-
    tive of a person of ordinary skill in the art at the time of the
    invention.
    VACATED AND REMANDED
    COSTS
    No costs.