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 Com-
mission, 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. s 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 Com-
mission precedent, and violates Commission policy to proceed
by rulemaking when changing rules affecting a broad seg-
ment 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.
__________
1 See 47 U.S.C. s 402(a) (1991); Capital Cities Communica-
tions, Inc. v. FCC, 554 F.2d 1135, 1136 n.1 (D.C. Cir. 1976).
I.
Section 22.925 of the Commission's rules provides, in perti-
nent part:
Cellular telephones installed in or carried aboard air-
planes, 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. s 22.925 (2000). Under s 1.3, the Commission has
authority to waive its rules "if good cause therefor is shown."
Id. s 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. Pursu-
ant to 47 C.F.R. s 2.104(d)(3)(i) and (ii), stations with second-
ary 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 protec-
tion from harmful interference" from such primary stations.
The AirCell system consists of specially engineered hand-
sets, ground stations, and so-called "smart" aircraft antennae
designed to provide low-power airborne cellular communica-
tions 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 intercon-
nected with the public switched network through the switches
of AirCell's participating licensees. In addition to hardware
and software modifications designed to provide cellular com-
munications 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 fre-
quency 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, s 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 amend-
ed 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 Telecom-
munications ("Bureau") conditionally granted the waiver re-
quests on December 24, 1998. Determining that the AirCell
system's potential for interference should be evaluated ac-
cording to its performance under normal operating conditions,
the Bureau found that "the record fully supports the conclu-
sion 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 tele-
phone[ ] in an airborne aircraft poses has been [satisfactorily]
addressed." Consequently, in the Bureau's view, the harm
that s 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 licen-
sees 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 de-
fined as "serious degradation, obstruction, or repeated inter-
ruption of cellular service."
On three occasions, the Bureau conditionally granted waiv-
ers 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 licen-
sees 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 deliberate-
ly 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 techni-
cal assessment of the AirCell system, including its judgment
that there is little risk the system will cause harmful interfer-
ence 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 opera-
tions. 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. s 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 harm-
ful 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 Bu-
reau's decision was based." Id. at 9627.
II.
Petitioners raise a variety of objections to the Commis-
sion's order. We address in Part A whether the Commission
violated its rules and the licensing scheme of the Communica-
tions 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.
s 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 Commis-
sion also "effectively modified all cellular carriers' licenses
nationwide without complying with Section 316 of the Com-
munications Act, 47 U.S.C. s 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.
s 22.905(a), provides: "Each channel block is assigned exclu-
sively to one licensee for use in that licensee's cellular geo-
graphic service area ("CGSA") (see s 22.911)." The second,
47 C.F.R. s 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. Ab-
sent 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 Com-
mission 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. ss 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 unautho-
rized 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 reason-
ably 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 char-
acterizing 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 li-
cense of its own, but instead purchases capacity to support
the AirCell service from participating cellular licensees pursu-
ant 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 s 22.925.
B.
Petitioners' challenges to the Commission's waiver of
s 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 repre-
sented 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 trans-
mit specially shaped patterns that reduce the risk of interfer-
ence. Because the Commission reasonably interpreted
s 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
s 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 underly-
ing the rule.
In identifying the public interest, see Keller Communica-
tions, 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 defer-
ence. 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 Associa-
tion of State Aviation Officials. Although the FAA did not
certify the AirCell system as dedicated public safety equip-
ment, 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 par-
ties by allowing AirCell to arbitrarily exempt any carrier of
its choice from the rule with no individualized showing, noth-
ing 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 clarifi-
cation on reconsideration, see 47 U.S.C. s 405, that the waiver
did not apply to commercial aircraft, the Commission's deci-
sion 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 interfer-
ence 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 com-
plaint, 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.
s 405(a)(2)); see also 47 C.F.R. s 1.115(b). The Commis-
sion'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 con-
cern is confined to one aspect of the Commission's explana-
tion.
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 evi-
dence before the Commission on the levels of harmful inter-
ference 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 con-
trary 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 Communica-
tions, 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 inter-
ference 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 unrelia-
ble, 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 interfer-
ence 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 Commis-
sion simply stated that they had relied on "unrealistic as-
sumptions, including the use of an unrealistically low interfer-
ence 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 realis-
tic." 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 Commis-
sion 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 explica-
tion, 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 thresh-
olds to the test data likewise does not fill in the gap, as the
Commission appears to suggest in its brief. The Commis-
sion'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 con-
flict 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 satis-
factory explanation for its action including a rational connec-
tion 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 con-
trary conclusion, however, the court is unable to discern why
the Commission considered one interference threshold prefer-
able to another or how it could extrapolate from the July 10,
1997, test data in the absence of a probability study. Accord-
ingly, we grant the petitions in part.