United States Court of Appeals

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued October 1, 2001 Decided November 9, 2001

No. 00-1304

AT&T Wireless Services, Inc., et al.,

Appellants

v\.

Federal Communications Commission,

Appellee

Northeast Communications of Wisconsin, Inc.,

d/b/a Cellcom,

Intervenors

Appeal from an Order of the

Federal Communications Commission

L. Andrew Tollin argued the cause for appellants. With him on the briefs
were Michael Deuel Sullivan, Douglas I. Brandon, Carol L. Tacker and
John T. Scott III.

Roberta L. Cook, Counsel, Federal Communications Commission, argued the
cause for appellee. With her on the brief was Daniel M. Armstrong,
Associate General Counsel.

Ronald J. Wiltsie II argued the cause for intervenors. With him on the
brief were Michele C. Farquhar, Ronnie London, Donald J. Evans, Timothy
Edward Welch, Russell D. Lukas and David L. Nace. David G. Leitch
entered an appearance.

Before: Edwards, Rogers and Tatel, Circuit Judges.

Opinion for the Court filed by Circuit Judge Rogers.

Rogers, Circuit Judge: In the order on review, the Federal
Communications Commission affirmed orders by the Bureau of Wireless
Telecommunications granting a waiver of 47 C.F.R. § 22.925 for two years
to permit AirCell, Inc. and cellular licensees that had entered into
resale agreements with AirCell to provide airborne cellular telephone
service. See AirCell, Inc., 15 F.C.C. Rcd. 9622 (2000). Petitioners AT&T
Wireless Services, Inc., Bell South Cellular Corp., SBC Wireless, Inc.,
and Cellco Partnership seek review of the Commission\'s order on three
principal grounds.[^1] First, they contend that the Commission violated
its rules as well as the licensing scheme of the 1934 Communications Act
by granting a waiver that modifies the licenses of existing licensees,
and by failing to require AirCell to apply for a license to provide a
new nationwide air-ground radio communications service. Second, they
contend that the waiver was arbitrary and capricious insofar as it
eviscerates the rule, contravenes Commission precedent, and violates
Commission policy to proceed by rulemaking when changing rules affecting
a broad segment of industry. Third, they contend that the Commission
failed to provide a reasoned explanation for its conclusion that harmful
interference was not likely to result from the AirCell system. We grant
the petitions in part, remanding the case to the Commission for further
explanation of one aspect of its waiver decision; otherwise we deny the
petitions.

**I.**

Section 22.925 of the Commission\'s rules provides, in pertinent part:

Cellular telephones installed in or carried aboard airplanes, balloons
or any other type of aircraft must not be operated while such aircraft
are airborne (not touching the ground). When any aircraft leaves the
ground, all cellular telephones on board that aircraft must be turned
off.

47 C.F.R. § 22.925 (2000). Under § 1.3, the Commission has authority to
waive its rules \"if good cause therefor is shown.\" Id. § 1.3.

AirCell, Inc. began developing and testing a low-power cellular system
installed on general aviation aircraft under a Special Temporary
Authority from the Commission in 1992. Two years later, the
Commission\'s Office of Engineering Technology authorized AirCell to
operate as an experimental radio station, providing service on a
secondary basis. Pursuant to 47 C.F.R. § 2.104(d)(3)(i) and (ii),
stations with secondary status \"\[s\]hall not cause harmful
interference to stations of primary services to which frequencies are
already assigned or may be assigned at later date,\" and \"\[c\]annot
claim protection from harmful interference\" from such primary stations.

The AirCell system consists of specially engineered handsets, ground
stations, and so-called \"smart\" aircraft antennae designed to provide
low-power airborne cellular communications without creating harmful
interference for other cellular networks. AirCell\'s ground stations are
co-located in rural areas at the cell sites of participating cellular
licensees, and customer traffic from the airborne mobile units is
interconnected with the public switched network through the switches of
AirCell\'s participating licensees. In addition to hardware and software
modifications designed to provide cellular communications at relatively
low power levels, the AirCell system seeks to minimize the potential for
harmful interference through the use of horizontal polarization,
specially shaped antenna patterns, non-standard control channels, and
frequency coordination with non-participating cellular providers. The
AirCell system was tested by AirCell and petitioners on July 10 and 11,
1997, using four sites in Texas and Oklahoma, and again by petitioners
on September 22, 1998, in Florida.

On October 9, 1997, AirCell filed a petition requesting that the
Commission waive, among other things, § 22.925 of its rules to permit
commercial deployment of AirCell service. Ten months later, AirCell and
a number of cellular licensees entering into resale agreements with
AirCell filed an amended petition to join the waiver request, thereby
establishing that the participating licensees had agreed to
modifications of their existing cellular licenses to authorize this
secondary use of their licensed spectrum. The Bureau of Wireless
Telecommunications (\"Bureau\") conditionally granted the waiver
requests on December 24, 1998. Determining that the AirCell system\'s
potential for interference should be evaluated according to its
performance under normal operating conditions, the Bureau found that
\"the record fully supports the conclusion that because of the lower
power, special antennas, and other features unique to the AirCell mobile
unit, the risk of harmful interference that use of an ordinary cellular
telephone\[ \] in an airborne aircraft poses has been \[satisfactorily\]
addressed.\" Consequently, in the Bureau\'s view, the harm that § 22.925
is intended to prevent \"will most likely not occur,\" and special
circumstances justified a waiver of the general rule. The Bureau
concluded a waiver was also warranted because the public safety benefits
to aircraft that will accrue from the use of the AirCell system serve
the public interest. Further, the Bureau observed, AirCell\'s voice and
data link promotes competition by providing small aircraft and general
aviation consumers an alternative to existing air-ground services.

The Bureau imposed nine special conditions on the waiver, including the
requirement that cellular service to airborne terminals be a secondary
service, and that participating licensees provide at least thirty days
prior notice of service or testing to co-block licensees with
transmitter sites within 270 kilometers of their ground stations. The
Bureau\'s conditions further stipulated that participating licensees had
a duty to provide information promptly on request of the Commission
regarding any complaint of interference, and an obligation to resolve
any instance of harmful interference, which was defined as \"serious
degradation, obstruction, or repeated interruption of cellular
service.\"

On three occasions, the Bureau conditionally granted waivers for
additional licensees. In so doing, the Bureau rejected the opposing
carriers\' arguments that, among other things, AirCell had taken over
obligations of the participating licensees and failed to provide proper
advance notice to opposing carriers. On reconsideration the Bureau also
clarified several waiver conditions and reduced the notification
distance from 270 to 151 kilometers, noting that during the Texas-
Oklahoma tests the airborne received signal \"was not strong enough to
interfere with terrestrial cellular communications, except when the
AirCell power control system was deliberately disabled for testing
purposes.\"

The Commission largely affirmed the Bureau\'s orders granting
conditional waivers and reset the two-year term of the waivers to begin
on June 9, 2000, the effective date of its order. The Commission
\"agree\[d\] with the Bureau\'s technical assessment of the AirCell
system, including its judgment that there is little risk the system will
cause harmful interference to non-participating carriers, as well as its
evaluation of the system\'s potential benefit for general aviation.\"
AirCell, 15 F.C.C. Rcd. at 9627. Based primarily on the design
characteristics of the AirCell system and the results of the first day
of the Texas-Oklahoma field tests on July 10 and 11, 1997, the
Commission concluded that AirCell had carried its burden of
affirmatively showing that its system is not likely to cause harmful
interference to terrestrial cellular operations. The Commission noted
that for the July 10, 1997, test,

AirCell chose a \"worst case\" scenario for site location, i.e., the
tests were conducted in a rural area where there was no urban noise to
mask the AirCell signal, and in a manner such that the AirCell airborne
mobile unit was close to the \"victim\" site and far from the AirCell
partner site. With this configuration, the AirCell mobile has to emit
its highest power level in order to reach its partner site. Even under
this configuration, the data from the first day of testing show that
there is little likelihood of harmful interference.

Id. at 9630 n.60. The Commission rejected as unpersuasive the evidence
presented by the opposing carriers and rejected the opposing carriers\'
remaining arguments that, for example, the AirCell system violated their
exclusive channel block assignments under 47 C.F.R. § 22.905(a), and
that their licenses were improperly modified by the AirCell order. By
relegating the AirCell system to secondary status in the cellular band
and requiring advance notification to help en-sure that all primary
cellular service is protected from harmful interference throughout the
waiver term, the Bureau had, in the Commission\'s view, provided
nonparticipating licensees with \"adequate, indeed redundant,
interference protection.\" Id. at 9629. At the same time, the Commission
disclaimed any reliance on a probability study submitted by AirCell. The
Commission added several other technical operating conditions \"to
ensure that the AirCell system will in fact operate within the technical
parameters on which the Bureau\'s decision was based.\" Id. at 9627.

**II.**

Petitioners raise a variety of objections to the Commission\'s order. We
address in Part A whether the Commission violated its rules and the
licensing scheme of the Communications Act by allowing AirCell to
provide a new nationwide radio communications service without a license.
In Part B, we address whether the waiver grant was arbitrary and
capricious. In Part C, we address whether the Commission failed to
provide a rational explanation for its conclusion that harmful
interference was not likely to result from the AirCell system.

Under our standard of review, the court must uphold the Commission\'s
order unless it is \"arbitrary, capricious, an abuse of discretion, or
contrary to law.\" 5 U.S.C. § 706(2)(A). See also Greater Boston
Television Corp. v. FCC, 444 F.2d 841, 851 (D.C. Cir. 1970).

**A.**

Contending that the Commission \"effectively granted the \[license\]
application that AirCell could not file\" consistent with Commission
rules, petitioners maintain that the Commission also \"effectively
modified all cellular carriers\' licenses nationwide without complying
with Section 316 of the Communications Act, 47 U.S.C. § 316.\" There is
no merit to these contentions.

The two relevant rules relate to geographic exclusivity and protection
from interference. The first, 47 C.F.R. § 22.905(a), provides: \"Each
channel block is assigned exclusively to one licensee for use in that
licensee\'s cellular geographic service area (\"CGSA\") (see §
22.911).\" The second, 47 C.F.R. § 22.911(d), provides in relevant part:
\"Within the CGSA determined in accordance with this section, cellular
systems are entitled to protection from co-channel and first-adjacent
channel interference and from capture of subscriber traffic by adjacent
systems on the same channel block.\" The Commission\'s interpretations
of its rules regarding the rights of cellular licensees, including the
right to channel block exclusivity and freedom from interference or
signal capture within a given CGSA, are entitled to substantial
deference. See Thomas Jefferson Univ. v. Shalala, 512 U.S. 504, 512
(1994); Trinity Broad. of Florida, Inc. v. FCC, 211 F.3d 618, 625 (D.C.
Cir. 2000). The court therefore will accept that these rules proscribe
only harmful interference within a given carrier\'s CGSA, which we
address in Part II C, infra. Absent harmful interference, AirCell\'s new
system does not trammel upon petitioners\' rights as licensees. See AMSC
Subsidiary Corp. v. FCC, 216 F.3d 1154, 1158-59 (D.C. Cir. 2000). Put
otherwise, the waiver does not mean that the licensees participating
with AirCell may provide airborne cellular service in a manner that
would conflict with the regulatory protections afforded to
nonparticipating carriers under their existing licenses. The Commission
emphasized the importance of AirCell\'s secondary status and advance
notification to nonparticipating carriers so that they can steer AirCell
away from use of particular channels. As the Commission explained, with
the grant of the waivers nothing changed insofar as the protections to
which existing licensees are entitled.

There is likewise no merit to petitioners\' contention that AirCell was
required to be licensed. See 47 U.S.C. §§ 301, 304, 307-310 (1991 &
Supp. 2001). So long as the licensees in partnership with AirCell
maintain actual control over the transmission equipment used in
AirCell\'s system and continue to abide by their own regulatory
obligations, the court has no basis for second-guessing the
Commission\'s description of AirCell as a \"reseller.\" Contrary to
petitioners\' contention, the Commission expressly rejected the claim
that an unauthorized transfer of control of the licensees\' operations
to AirCell had occurred. The Commission stated that \"\[i\]n the case of
a nationwide network such as AirCell is attempting to build, \... the
AirCell partners, while remaining responsible for complying with
Commission requirements \... may reasonably and prudently assign a
single entity the task of being a central contact point for system
management and system/site termination purposes.\" Aircell, 15 F.C.C.
Rcd. at 9643.

Nor did the Commission contravene its precedent in characterizing
AirCell\'s relationship to its participating carriers as a resale. See
Resale and Shared Use, Docket 20097, Report and Order, 60 F.C.C.2d 261,
263 (1976), recon., 62 F.C.C.2d 588 (1977), aff\'d sub nom. AT&T v. FCC,
572 F.2d 17 (2d Cir.), cert. denied, 439 U.S. 875 (1978). As the Bureau
explained in rejecting the argument that AirCell is a facilities-based
service provider seeking co-primary status with non-participating
cellular licensees, \"AirCell holds no cellular license of its own, but
instead purchases capacity to support the AirCell service from
participating cellular licensees pursuant to resale agreements.\"
AirCell\'s partners have agreed to modifications of their licenses to
permit this secondary use of their licensed spectrum. An analogous
situation existed with regard to the credit card facilitator of railroad
cellular service in GTE Airfone, GTE Railfone, and GTE Mobilnet, 8
F.C.C. Rcd. 6171 (Aug. 27, 1993).

For these reasons, the court affirms the Commission\'s determination
that the only legal obstacle to the launch of AirCell\'s system was the
bar in § 22.925.

**B.**

Petitioners\' challenges to the Commission\'s waiver of § 22.925 as
arbitrary and capricious are also meritless.

In WAIT Radio v. FCC, 418 F.2d 1153 (D.C. Cir. 1969), the court
explained that the \"agency\'s discretion to proceed in difficult areas
through general rules is intimately linked to the existence of a safety
valve procedure for consideration of an application for exemption based
on special circumstances.\" Id. at 1157. Waiver is thus appropriate when
\"particular facts would make strict compliance inconsistent with the
public interest.\" Northeast Cellular Tel. Co. v. FCC, 897 F.2d 1164,
1166 (D.C. Cir. 1990). Given the Commission\'s findings about the unique
capability of the AirCell system to provide low power non-degrading
cellular service and its contributions to the public interest,
petitioners\' challenge to the Commission\'s decision to act by waiver
rather than by rulemaking is unpersuasive.

The Commission\'s concern has been with the serious risk of harmful
interference to terrestrial systems from the greatly enhanced
transmitting range of ordinary cellular telephones used aboard airborne
aircraft. See Airborne Use of Cellular Telephones, 7 F.C.C. Rcd. 23
(Dec. 30, 1991). AirCell represented to the Commission that most
conventional cellular systems are optimized for vertical wave
polarization; as a result, horizontally polarized signals used by the
AirCell system are less prone to capture by terrestrial receiving
antennas. The Commission noted that \"smart\" antennae mounted on
AirCell-equipped aircraft are designed to transmit specially shaped
patterns that reduce the risk of interference. Because the Commission
reasonably interpreted § 22.925 as being intended to protect against
only harmful interference from airborne cellular telephone use,
petitioners\' contention that the waiver \"eviscerates\" the purpose of
§ 22.925 necessarily fails. Cf. Busse Broad. Co. v. FCC, 87 F.3d 1456,
1463-64 (D.C. Cir. 1996). The Commission could reasonably conclude that
when combined with the use of non-standard control channels and
frequency coordination with nonparticipating licensees, the collective
effect of AirCell\'s low-power technological design serves to minimize
the risk that its operations will degrade the signals of other cellular
service providers, thereby addressing the concerns underlying the rule.

In identifying the public interest, see Keller Communications, Inc. v.
FCC, 130 F.3d 1073, 1076 (D.C. Cir. 1997), the Commission found \"few
viable alternatives that may provide \'safety-related voice
communications between pilots and emergency personnel, and can be used
to uplink in-cockpit, up-to-the-minute-weather and air traffic
information as well as potentially provide in-flight monitoring of
airframe and engine operations, serving to better inform ground
personnel of aircraft operations.\' \" AirCell, 15 F.C.C. Rcd. at 9644.
The Commission\'s determination is owed considerable deference. See
Metro. Council of NAACP Branches v. FCC, 46 F.3d 1154, 1164 (D.C. Cir.
1995); Health and Med. Policy Research Group v. FCC, 807 F.2d 1038, 1043
(D.C. Cir. 1987). The record before the Bureau included supportive
statements by the National Transportation Safety Board, the Federal
Aviation Administration (\"FAA\"), and the National Association of State
Aviation Officials. Although the FAA did not certify the AirCell system
as dedicated public safety equipment, the Commission observed that the
FAA noted several public benefits that could be derived from the system,
and that on balance, in view of the protections for primary cellular
service, these benefits justified granting the waiver. The Commission\'s
conclusion that the waiver will offer significant public safety benefits
is thus amply supported by the record.

Petitioners\' remaining challenges need only brief response. First,
contrary to petitioners\' contention that the \"me-too\" waiver process
unlawfully delegates authority to private parties by allowing AirCell to
arbitrarily exempt any carrier of its choice from the rule with no
individualized showing, nothing in the order indicates that the
Commission granted AirCell exclusive authority to provide nationwide
airborne cellular service. The waiver is limited to two years, and the
order does not state that a similar service provider could not also
obtain a waiver.

Second, because the opposing carriers did not seek clarification on
reconsideration, see 47 U.S.C. § 405, that the waiver did not apply to
commercial aircraft, the Commission\'s decision and order can hardly be
faulted for failing specifically to address commercial aircraft.

Third, petitioners cannot now contend that the protection provided by
the secondary status of AirCell\'s operation is \"illusory\" should
interference occur because tracing interference to AirCell operations is
\"infeasible\" and recourse to the complaint process will be
ineffective. The opposing carriers\' application for review of the
Bureau\'s waiver orders did not challenge the feasibility of initiating
an interference complaint, and hence the Commission was not afforded a
fair opportunity to pass on the issue. See Bartholdi Cable Co. v. FCC,
114 F.3d 274, 279-80 (D.C. Cir. 1997) (citing 47 U.S.C. § 405(a)(2));
see also 47 C.F.R. § 1.115(b). The Commission\'s decision was adopted on
May 24, 2000, and petitioners do not dispute that the ex parte letters
on which they rely, dated April 4, 2000, and June 5, 2000, were
untimely. The brief reference in petitioners\' September 24, 1999, reply
(to AirCell\'s opposition to review of the Bureau\'s reconsideration
order) to problems documenting overflights of brief duration concerned
whether the Bureau erred in allowing AirCell operations on DCMA
guardband channels, and thus cannot fairly be said to have alerted the
Commission to a different issue, namely, the feasibility of enforcing
AirCell\'s status as a secondary service. See, e.g., Alianza Federal de
Mercedes v. FCC, 539 F.2d 732, 739 (D.C. Cir. 1976).

**C.**

Although petitioners raise a host of claims in contending that the
Commission had no basis for its determination that it was not likely
that AirCell\'s operations would cause harmful interference to
terrestrial cellular systems, the court\'s concern is confined to one
aspect of the Commission\'s explanation.

The parties agree that for terrestrial cellular service to remain
effective, the signal from a terrestrial cell phone must sufficiently
exceed the electromagnetic noise floor of the location where the call is
received, plus whatever interference may be generated by a concurrent
AirCell signal (i.e., the so-called \"signal-to-noise-plus-interference
ratio\"). AirCell claims, and petitioners do not appear to dispute, that
the industry standard for this ratio is 17dB. Conversely, and as a
corollary principle, interference from an AirCell signal that falls
within the existing noise floor should not be detectable to a
terrestrial cell phone user, much less degrade a terrestrial signal
utilizing the same frequency within the same CGSA. Apart from this
baseline understanding, however, the evidence before the Commission on
the levels of harmful interference that AirCell\'s system could cause
was in conflict.

On the one hand, AirCell submitted reports indicating that there was
virtually no chance that its service would cause harmful interference to
terrestrial cellular operations. A report prepared by AirCell
consultants, TEC Cellular, Inc. (\"TECC\"), found that virtually all
interference from AirCell signals in urban, suburban, and rural areas
fell within the existing noise floors of those environments during
normal operations. Relying largely on measured signal strength data from
the July 10, 1997, test runs, which were designed to simulate \"normal\"
operating conditions (i.e., with all AirCell components operational and
airplanes flying point-to-point paths), the TECC report concluded that
\"\[f\]ull scale AirCell operation, properly deployed and engineered,
will cause a level of interference to terrestrial calls so low that
while it may be detectable with sensitive test equipment, it should be
imperceptible to terrestrial callers.\" In addition, AirCell submitted a
report incorporating the results of a probability study, based also on
the July 10, 1997, test data, which concluded that there was only a
five-in-a-million chance that an AirCell call could noticeably degrade a
terrestrial call.

On the other hand, the opposing carriers submitted contrary analyses of
the test data. For example, an engineering report submitted by Dr.
William C. Y. Lee, Vice President and Chief Scientist, and Mark Schulz,
Technology Director of the Strategic Technology Group of AirTouch
Communications, Inc., concluded, based on the July 10 and 11, 1997, test
data, that harmful interference was likely to occur 30% of the time.
They based this conclusion on the assumption that the test runs employed
on both days are equally probable to occur during actual operations, and
that a minus 124 dBm interference threshold should be employed in
calculating the likelihood of harmful interference, rather than the
minus 117 dBm threshold used for acceptable voice quality in the
interference assessment submitted by AirCell, or the minus 110 dBm
threshold used in the TECC report as a reasonable lower limit on an
acceptable ground call. In addition, Dr. Lee and Mr. Schulz claimed that
there was no test data below the 5000\' altitude level, notwithstanding
a \"disturbing trend\" showing higher interference levels at
progressively lower altitudes, and that there was no mechanism in the
AirCell system to terminate and block calls below 5000\'.

The Commission adequately explained why it rejected the July 11, 1997,
Texas-Oklahoma test data and the September 22, 1998, Florida test data
upon which petitioners rely. The July 11, 1997, test runs were conducted
without the dynamic power control element, which eliminated the benefits
of one of the main components of the AirCell design. In addition, the
flight patterns employed on that date were abnormal, such that the
Commission concluded that they simulated conditions approximating a
\"major malfunction.\" AirCell, 15 F.C.C. Rcd. at 1630. For similar
reasons, the Commission discarded the Florida test results, which also
involved abnormal flight patterns around a \"victim\" cell site at close
range and low altitude. The Commission further noted that the opposing
carriers had installed the wrong type of antenna during the Florida
test, did not record the AirCell mobile transmitter power output, and
deliberately matched the supervisory audio tone to prevent the AirCell
telephone from hanging up once it had lost a usable signal from the
AirCell ground station. In addition, given its view that the results of
the second day of the Texas-Oklahoma tests and the Florida tests were
unreliable, the Commission sufficiently justified its rejection of the
opinions of the chief operating officers of six major cellular carriers
for lack of credible supporting evidence. Finally, the Commission
reasonably explained that concern about interference from uptilted
antennas was adequately addressed by the ordinary coordinating process
that every cellular licensee must conduct under Commission rules.

However, in rejecting the report of Dr. Lee and Mr. Schulz, the
Commission provided no such clarity as to its choice of the appropriate
interference threshold. Rather, the Commission simply stated that they
had relied on \"unrealistic assumptions, including the use of an
unrealistically low interference threshold.\" Id. at 9631. In the
Commission\'s view, use of a threshold of minus 124dBm was \"too
conservative and \... an interference threshold of minus 117 dBm is more
realistic for typical analog systems.\" Id. at 9631 n.67. This may be
so, and the court would otherwise defer to the Commission\'s expertise.
See Keller Communications, 130 F.3d at 1078. But the Commission\'s
succinct statement fails to provide a reasoned justification for
rejecting the minus 124 dBm threshold, much less a defense of the minus
117 dBm threshold that the Commission viewed as being \"more
realistic.\" Nor does the Commission indicate that it was relying on any
rules or standards regarding such determinations. The omission of an
explanation of its choice of an interference threshold is particularly
troubling because the July 10, 1997, test data, which was the only test
data on which the Commission apparently relied, did not represent the
full range of operational conditions in which AirCell\'s phones are
likely to be used.

The only other clarification that the Commission provided was a
conclusory assessment, again without further explication, that
\"\[b\]ased on our review of the evidence, it appears to us that use of
the latter \[minus 117 dBm\] threshold would have led to a finding that
AirCell would cause a significant level of harmful interference 0% of
the time.\" Id. Obviously, this does not fill the void. Nor, of course,
can the fact that AirCell used the minus 117 dBm threshold in its own
report suffice to explain the Commission\'s choice. That petitioners may
not dispute the results of applying different dBm thresholds to the test
data likewise does not fill in the gap, as the Commission appears to
suggest in its brief. The Commission\'s failure to justify adequately
its choice of an interference threshold thus implicates its additional
failure to explain how it was able, in the absence of a probability
study, to translate the raw signal data from the July 10, 1997, field
test into a finding that AirCell\'s system \"would cause a significant
level of harmful interference 0% of the time\" in the real world.

Conclusory explanations for matters involving a central factual dispute
where there is considerable evidence in conflict do not suffice to meet
the deferential standards of our review. Basic principles of
administrative law require the agency to \" \'examine the relevant data
and articulate a satisfactory explanation for its action including a
rational connection between the facts found and the choice made.\' \"
U.S. Telecom Ass\'n v. FCC, 227 F.3d 450, 461 (D.C. Cir. 2000) (quoting
Motor Vehicle Mfrs. Ass\'n v. State Farm Mut. Auto. Ins. Co., 463 U.S.
29, 43 (1983)). The Commission may well be able, based on the record
that was before it, to resolve satisfactorily the issue of harmful
interference in AirCell\'s favor. Indeed, the explanation for its
conclusion in AirCell\'s favor may be relatively simple and briefly
stated. Because there is too much evidence in the record suggesting a
contrary conclusion, however, the court is unable to discern why the
Commission considered one interference threshold preferable to another
or how it could extrapolate from the July 10, 1997, test data in the
absence of a probability study. Accordingly, we grant the petitions in
part.

[^1]: See 47 U.S.C. § 402(a) (1991); Capital Cities Communications, Inc.
    v. FCC, 554 F.2d 1135, 1136 n.1 (D.C. Cir. 1976).