                               UNPUBLISHED

                  UNITED STATES COURT OF APPEALS
                      FOR THE FOURTH CIRCUIT


                               No. 08-2155


GEORGE WELCH FOLK; TIMOTHY BRIAN FOLK,

                Petitioners,

           v.

ROBERT A. STURGELL, Acting Administrator Federal Aviation
Administration,

                Respondent.



On   Petition  for   Review      of  an   Order   of  the    National
Transportation Safety Board.     (SE-18005; SE-18018)


Argued:   March 23, 2010                     Decided:   April 22, 2010


Before DUNCAN and DAVIS, Circuit Judges, and Joseph R. GOODWIN,
Chief United States District Judge for the Southern District of
West Virginia, sitting by designation.


Affirmed by unpublished opinion.        Judge Duncan wrote        the
opinion, in which Judge Davis and Judge Goodwin joined.


Robert Giacinto Blackford, ALLEN & BLACKFORD, PC, Gaithersburg,
Maryland, for Petitioners.     Laura Jennings, FEDERAL AVIATION
ADMINISTRATION, Washington, D.C., for Respondent.


Unpublished opinions are not binding precedent in this circuit.
DUNCAN, Circuit Judge:

       This    appeal           arises   from    a     National       Transportation        and

Safety Board (“Board”) decision affirming an Administrative Law

Judge’s       (“ALJ”)           determination        that     Petitioners       George      and

Timothy      Folk     violated       Federal     Aviation       Administration         (“FAA”)

regulations.               The     issues    before          this     court    are     whether

substantial evidence supports the finding that Petitioners flew

over    a    “congested          area”   according      to     14    C.F.R.    § 137.51     and

whether       the        term     “congested        area”     violates        the    vagueness

doctrine under the Due Process Clause.                              For the reasons that

follow, we affirm.



                                                I.

       George Folk owns a farm in Martinsburg, West Virginia, and

operates a crop-dusting business with his son Timothy Folk.                                    On

May    30,    2006,       FAA    Inspector      George       Cooper    Towers       received   a

complaint about Petitioners flying too low.                             During a routine

inspection on June 16, 2006, Towers told Petitioners that he had

received a complaint about low flying and warned them that they

must    submit       a    “congested      area       plan”    before     flying      over   any

congested area.            When Petitioners asked what the term “congested

area”       meant,        Towers     responded        that     no     precise       definition

existed.       He explained, however, that “a group of . . . as few

as two or three houses . . . may be considered congested.”                                  J.A.

                                                2
95.      The significance of designating an area as congested is

that if complaints are made with respect to an area that is

determined to be congested, and no congested area plan has been

filed, the FAA will initiate an enforcement action.                            However,

the    filing     of    a    congested       area    plan   is    not    considered     an

admission that the proposed area is indeed congested.

       On July 31, 2006, and September 9, 2006, Petitioners flew

their plane near the intersection of Swan Pond Road and Hollida

Lane     in    Martinsburg.            Because       they   considered       this    area

uncongested,       Petitioners         did    not    file   a    congested    area    plan

before        either    flight.            When      neighbors     complained        about

Petitioners’           low     flying,        Towers        initiated        enforcement

proceedings       against      them.         After     conducting       an   evidentiary

hearing, the ALJ determined that Petitioners had violated FAA

regulations because the area near the intersection of Swan Pond

Road   and      Hollida      Lane   was,     in     fact,   congested.        The    Board

affirmed.       This appeal followed.



                                             II.

       Petitioners argue that the term “congested area” violates

the vagueness doctrine under the Due Process Clause, and that

substantial       evidence      does    not    support      the   determination       that

they flew over a congested area.                     In order to provide context

for these issues, we begin with a discussion of the relevant

                                              3
regulatory     framework.        We    then    address   each   of    Petitioners’

contentions in turn.



                                         A.

       FAA    regulations       generally       prohibit    low      flying      over

congested areas.          For example, Section 91.119 of Chapter 14 of

the Code of Federal Regulations, which establishes “[m]inimum

safe altitudes,” provides:

       Except when necessary           for takeoff or landing, no
       person may operate an           aircraft below the following
       altitudes:

                                   *      *      *

       (b) Over congested areas. Over any congested area of
       a city, town, or settlement, or over any open air
       assembly of persons, an altitude of 1,000 feet above
       the highest obstacle within a horizontal radius of
       2,000 feet of the aircraft.

       (c) Over other than congested areas.    An altitude of
       500 feet above the surface, except over open water or
       sparsely populated areas.       In those cases, the
       aircraft may not be operated closer than 500 feet to
       any person, vessel, vehicle, or structure.

14   C.F.R.    § 91.119.       This    section    governs   “the     operation      of

aircraft within the United States and within 12 nautical miles

from the coast of the United States.”                Id. § 91.101.

       FAA    regulations      provide   for     more    lenient     treatment      of

agricultural aircraft.          Sections 137.49 and 137.51 of Chapter 14

also    concern      minimum    altitudes,      but    “apply   to    persons    and

aircraft      used   in   agricultural        aircraft   operations.”         Id.    §

                                          4
137.29(a).   Section 137.49 regulates “[o]perations over other

than congested areas,” providing:

      Notwithstanding Part 91 of this chapter, during the
      actual dispensing operation, including approaches,
      departures, and turnarounds reasonably necessary for
      the operation, an aircraft may be operated over other
      than congested areas below 500 feet above the surface
      and closer than 500 feet to persons, vessels,
      vehicles, and structures, if the operations are
      conducted without creating a hazard to persons or
      property on the surface.

Id.   § 137.49.    Section   137.51   regulates   “[o]peration    over

congested areas,” providing:

      (a) Notwithstanding Part 91 of this chapter, an
      aircraft may be operated over a congested area at
      altitudes required for the proper accomplishment of
      the agricultural aircraft operation if the operation
      is conducted --

          (1) With the maximum safety to persons            and
          property on the surface, consistent with          the
          operation; and

          (2) In accordance with the         requirements    of
          paragraph (b) of this section.

      (b) No person may operate an aircraft over a congested
      area except in accordance with the requirements of
      this paragraph.

          (1) Prior written approval must be obtained from
          the appropriate official or governing body of the
          political subdivision over which the operations
          are conducted.

          (2) Notice of the intended operation must be
          given to the public by some effective means, such
          as daily newspapers, radio, television, or door-
          to-door notice.

          (3) A plan for each complete operation must be
          submitted  to,  and  approved  by   appropriate

                                 5
            personnel of the FAA Flight Standards District
            Office having jurisdiction over the area where
            the operation is to be conducted. The plan must
            include consideration of obstructions to flight;
            the   emergency   landing  capabilities  of   the
            aircraft   to   be   used;   and   any  necessary
            coordination with air traffic control.

Id. § 137.51.     Subsection (b) further provides: “No person may

operate any multiengine aircraft over a congested area below the

altitudes prescribed in Part 91 of this chapter except during

the   actual   dispensing     operation,   including    the     approaches,

departures, and turnarounds necessary for that operation.”              Id.

§ 137.51(b)(5)(iii). 1

      The   regulations   never   define   “congested   area”    or   “other

than congested area.”       At the relevant time, the FAA Inspectors’

Handbook 8700.1 provided the only guidance:

      H. Considerations for Congested Area Determinations.
      The term congested area has been applied on a case by
      case basis since it was first used.        No precise
      mathematical   or  geographic   definition  has   been
      developed. The rule is clear that the congested area
      must be an area of a city, town, or settlement.
      However, some guidelines have been developed to assist
      in interpretation:

            (1) The purpose of the rule is to provide minimum
            safe altitudes for flight and to provide adequate
            protection to persons on the ground.           The
            following areas were determined to be congested
            by the Civil Aeronautics Board, in past cases:


      1
        Section 137.51(b)(5)(iii) rebuts Petitioners’ argument
that section 91.119 was never intended to apply to agricultural
aircraft.



                                    6
                 (a) Approximately 10 houses and a school,

                 (b) the campus of a university,

                 (c) a crowded beach area along a highway,
                 and

                 (d) a boy’s camp where numerous people were
                 on the docks and the shore.

            (2) The presence of people is important to the
            determination of whether an area is “congested.”

            (3) The term is administered to prohibit over
            flights that cut the corners of large, heavily
            congested, residential areas.

            (4) No definition has been constructed, which
            determines the allowable number of people, the
            amount of ground traffic, the proximity of
            buildings to each other, the number of buildings
            or residences, or other conditions that exist in
            a particular area, to both protect persons or
            property on the ground and allow agricultural
            aircraft operations to take place.

J.A. 216.      The Handbook added, regarding section 137.49, that

where   “the   pilot   of   an   agricultural   aircraft   dispenses    an

economic poison on a field adjacent to a farmhouse,” he “may

operate less than 500 feet above the surface or closer than 500

feet to the house provided the house or its occupants are not

exposed to hazard from the aircraft or the chemicals.”                 J.A.

216.




                                     7
       Petitioners          contend    that       section    137.49    applies     here

because they flew over a non-congested area. 2                    By contrast, the

FAA contends that section 137.51 applies because they flew over

a congested area.            Thus the question before the ALJ was whether

the relevant area was congested for purposes of section 137.51.



                                           B.

       Petitioners argue that because the term “congested area”

does       not   have   a   clear     meaning,     section    137.51    violates   the

vagueness doctrine under the Due Process Clause.                       We review this

issue de novo. 3        See United States v. Williams, 364 F.3d 556, 559

(4th Cir. 2004).

       2
       We note, but need not decide, that section 137.49 may not
have assisted Petitioners even if the relevant area had not been
congested. One witness testified before the ALJ that one of the
relevant flights caused a “loud rumble” in his house that
sounded like “someone had hit [the] house.”    S.J.A. 12.   When
the resident of the house went outside to investigate, the plane
flew over him four different times at an altitude of about 100
to 300 feet.   The witness testified that he did not “feel safe
having a plane flying at such altitude over [his] residence.”
S.J.A. 16-17.   These circumstances might have been interpreted
as “creating a hazard to persons or property on the surface”
under section 137.49. 14 C.F.R. § 137.49.
       3
       Notably, the Board would have lacked jurisdiction to
entertain Petitioners’ constitutional challenge to “congested
area” in section 137.51. See Adm’r v. Eby, 3 N.T.S.B. 614, 615
(N.T.S.B. 1977) (“With respect to respondent’s attack on the
regulations as unconstitutionally vague (due to the absence of a
definition of ‘congested area’), the Board has consistently held
that it lacks jurisdiction to entertain attacks on the validity
of the [Federal Aviation Regulations].”).


                                              8
     Petitioners   must   show   that   the   relevant   section   was

impermissibly vague as applied to them. 4     We have explained the

relevant test as follows:

     A statute is impermissibly vague if it either (1)
     fails to provide people of ordinary intelligence a
     reasonable opportunity to understand what conduct it
     prohibits   or   (2) authorizes    or   even  encourages
     arbitrary    and    discriminatory    enforcement. . . .
     Stated differently, a court considering a vagueness
     challenge must determine if the statutory prohibitions
     are set out in terms that the ordinary person
     exercising ordinary common sense can sufficiently
     understand and comply with.

United States v. Whorley, 550 F.3d 326, 333 (4th Cir. 2008)

(internal quotations and citations omitted).       The Supreme Court

has explained that under certain circumstances this test should

be applied less stringently:

     These standards should not, of course, be mechanically
     applied.      The  degree   of   vagueness  that   the
     Constitution tolerates -- as well as the relative
     importance of fair notice and fair enforcement --
     depends in part on the nature of the enactment. Thus,
     economic regulation is subject to a less strict
     vagueness test because its subject matter is often
     more narrow, and because businesses, which face
     economic demands to plan behavior carefully, can be

     4
       We assume, for purposes of our analysis, that Petitioners
are bringing an as-applied challenge to section 137.51.
Petitioners do not make clear whether they are bringing a facial
or an as-applied challenge. However, a facial challenge appears
inapplicable in this case.     To make out a facial challenge,
Petitioners would have to “demonstrate that the law is
impermissibly vague in all of its applications.”       Vill. of
Hoffman Estates v. Flipside, Hoffman Estates, Inc., 455 U.S.
489, 497 (1982).    That cannot be done here because “congested
area” plainly covers densely populated urban settings.



                                  9
        expected to consult relevant legislation in advance of
        action. Indeed, the regulated enterprise may have the
        ability to clarify the meaning of the regulation by
        its own inquiry, or by resort to an administrative
        process.     The Court has also expressed greater
        tolerance   of  enactments   with   civil  rather   than
        criminal   penalties   because   the   consequences   of
        imprecision are qualitatively less severe.

Vill.    of   Hoffman    Estates,    455    U.S.    at    498-99      (footnote     call

numbers omitted); see Greenville Women’s Clinic v. Comm’r, S.C.

Dep’t of Health & Envtl. Control, 317 F.3d 357, 366 (4th Cir.

2002).

       Petitioners      cannot   show    that      they    lacked      “a   reasonable

opportunity      to     understand       what      conduct        [section      137.51]

prohibits.”      Whorley, 550 F.3d at 333 (quotations and citation

omitted).     Because Towers warned that two or three houses may be

considered a congested area, Petitioners had reason to believe

that the residential area near the intersection of Swan Pond

Road    and   Hollida    Lane    might   be     congested.         They     could   have

resolved any doubt by filing a congested area plan for that

intersection and waiting for Towers’s response.                           Furthermore,

Petitioners      have    not     tried     to    show      that       section    137.51

“authorizes     or    even     encourages       arbitrary       and    discriminatory

enforcement,”     nor    have    they    presented        any   evidence     that    the

enforcement action against them was arbitrary.                        Id. (quotations

and citation omitted).            Therefore, Petitioners have failed to

show that section 137.51 is unconstitutionally vague.


                                         10
                                       C.

       We next consider the ALJ’s and Board’s determination that

Petitioners flew over a congested area.             The decision below must

be     set   aside    if   that     determination     is    “unsupported       by

substantial evidence.”          5 U.S.C. § 706(2)(E); see North Carolina

v. Fed. Aviation Admin., 957 F.2d 1125, 1128 (4th Cir. 1992).

Substantial evidence is “‘such relevant evidence as a reasonable

mind    might    accept    as    adequate   to   support     a       conclusion.’”

Platone v. U.S. Dep’t of Labor, 548 F.3d 322, 326 (4th Cir.

2008) (quoting Consol. Edison Co. of N.Y. v. NLRB, 305 U.S. 197,

229 (1938)).

       In this case, the Board made clear that the question of

what    constitutes    a   “congested   area”    involves        a   case-by-case

inquiry that considers all relevant circumstances:

       The term “congested area” will continue to be
       adjudicated on a case-by-case basis before this Board.
       The determination must take into consideration all
       circumstances, not only the size of an area and the
       number of homes or structures, but, for example,
       whether the buildings are occupied or people are
       otherwise present, such as on roads.

J.A. 276-77.      This approach is consistent with the Board’s prior

case law.       See Eby, 3 N.T.S.B. at 615 (determining that an area

was congested after “[c]onsidering the size of the area and the

number of homes, and the corresponding density of residences,

and after viewing the aerial photographs”).                Therefore, we must

determine whether substantial evidence supports the ALJ’s and

                                       11
Board’s finding that, given all relevant circumstances, the area

near the intersection of Swan Pond Road and Hollida Lane was

congested.

     After    carefully   reviewing    the   record,   we    note   that

approximately thirty houses are located in the general vicinity

of   that    intersection.     The     record   further     shows   that

Petitioners’ flights passed over corner sections of that area.

We therefore conclude that the area over which Petitioners flew

could reasonably be considered congested based on substantial

evidence in the record.



                                III.

     For the reasons stated above, we

                                                                AFFIRM.




                                 12
