FAA v. NTSB

United States Court of Appeals

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued April 8, 1999 Decided September 21, 1999

No. 98-1365

Jane F. Garvey, Administrator,
Federal Aviation Administration,
Petitioner

v.

National Transportation Safety Board and
Richard Lee Merrell,
Respondents

On Petition for Review of Orders of the
United States Department of Transportation

E. Roy Hawkens, Attorney, U.S. Department of Justice,
argued the cause for petitioner. With him on the briefs were
Frank W. Hunger, Assistant Attorney General at the time
the briefs were filed, David W. Ogden, Acting Assistant
Attorney General, Robert S. Greenspan, Attorney, and James
W. Tegtmeier, Attorney, Federal Aviation Administration.

 Clay Warner argued the cause for respondents. With him
on the brief was James W. Johnson.

Before: Wald, Randolph and Garland, Circuit Judges.

Opinion of the Court filed by Circuit Judge Garland:

Garland, Circuit Judge: The Federal Aviation Administra-
tion (FAA) issued an enforcement order to Captain Richard
Merrell, a Northwest Airlines pilot whom the FAA deter-
mined had violated airline safety regulations. Merrell appeal-
ed to the National Transportation Safety Board (NTSB),
which ruled in his favor and dismissed the FAA's order. The
FAA petitions for review of that decision, arguing that the
NTSB erroneously failed to defer to the FAA's reasonable
interpretation of its own regulations. We grant the petition,
reverse the NTSB, and remand for further proceedings con-
sistent with this opinion.

I

The Federal Aviation Act, 49 U.S.C. ss 40101 et seq.,
establishes a "split-enforcement" regime in which the FAA
has regulatory and enforcement authority, while the NTSB
acts as an impartial adjudicator. See Hinson v. NTSB, 57
F.3d 1144, 1147 n.1 (D.C. Cir. 1995). We begin by setting
forth the facts and procedural history of Captain Merrell's
case, and then describe the nature of the split-enforcement
regime in more detail.

A

The facts of the case are undisputed. On June 19, 1994,
Merrell was the pilot-in-command of a commercial passenger
plane, Northwest Flight 1024. After Flight 1024 took off in
the heavily trafficked Los Angeles area, air traffic control
(ATC) instructed it to climb to and maintain an altitude of
17,000 feet. Merrell correctly repeated, or "read back," this
instruction to ATC. About a minute later, ATC transmitted
an altitude clearance to another aircraft, American Airlines
Flight 94, directing it to climb to and maintain an altitude of

23,000 feet. The American flight promptly and correctly
acknowledged this clearance with its own "readback."

Merrell, however, mistakenly thought that the instruction
to American was intended for his aircraft, so he also read the
instruction back to ATC. Unfortunately, because Merrell
made his readback at the same time as the American pilot,
his transmission was blocked, or "stepped on." The ATC
radio system can handle only one transmission at a time on
any given frequency; when two transmissions overlap, both
may become blocked or garbled, or the stronger signal alone
may be heard (i.e., it may "step on" the weaker signal). ATC
can often detect that a transmission has been stepped on
because, unless the signals overlap completely, ATC will
receive a portion of the stepped-on message, and because a
loud buzzing noise usually accompanies the period of overlap.
On rare occasions, however, two transmissions will overlap
completely without creating an identifiable buzz. This ap-
pears to have happened in Merrell's case. His readback
apparently coincided precisely with that of American Flight
94, and as a result his transmission was entirely blocked.
ATC heard neither Merrell's readback nor any indication that
it had occurred. And because ATC did not hear the errone-
ous readback, it could not correct Merrell's mistake.

Meanwhile Merrell, unaware that ATC had not received his
transmission, proceeded to ascend toward 23,000 feet. As the
Northwest flight rose from its assigned altitude, the ATC
controller noticed the deviation and directed the aircraft to
return to 17,000 feet. Before Merrell could comply, he had
ascended to 18,200 feet and lost the standard safety separa-
tion required between commercial flights.

On November 3, 1995, the FAA issued an enforcement
order against Merrell. The order alleged that Merrell had
violated FAA safety regulations by, inter alia, (1) "operat[ing]
an aircraft contrary to an ATC instruction in an area in which
air traffic control is exercised," in violation of 14 C.F.R.
s 91.123(b); and (2) "operat[ing] an aircraft according to a
clearance or instruction that had been issued to the pilot of
another aircraft for radar air traffic control purposes," in

violation of 14 C.F.R. s 91.123(e). Joint Appendix (J.A.) at
7.1

Merrell appealed the FAA's order to the NTSB. At the
outset of the proceedings, the FAA agreed that because
Merrell had filed a timely incident report pursuant to the
FAA Aviation Safety Reporting Program, it would waive any
sanction for the alleged violations. See J.A. at 11. It sought
affirmance of its enforcement order, however, arguing that
Merrell had deviated from clearly transmitted ATC instruc-
tions, that this mistake was due to his own carelessness
rather than to ATC error, and that the deviation therefore
constituted a regulatory violation. The Administrative Law
Judge (ALJ) agreed and affirmed the order. The ALJ found,
based on both the recording and the transcript of the radio
communications, that the ATC transmission to American
Flight 94 had been clear and that the instruction to climb to
23,000 feet had plainly not been intended for Merrell's air-
craft. Id. at 14-15. Indeed, after Merrell listened to the
tape, he conceded that he had simply "misheard" the instruc-
tion. See id. at 18-19; NTSB Record (R.) at 145. The ALJ
concluded that the fact that Merrell's readback was stepped
on did not absolve "Captain Merrell of his responsibility to
hear that [the] initial clearance" was for another flight. J.A.
at 26. He explained that: "[A]viation is ... particularly
unforgiving of carelessness or neglect. And in this particular
case, the initial mistake was made by Captain Merrell, and
he's going to have to be responsible for it." Id. at 27.
Accordingly, the ALJ held that Merrell "was in regulatory
violation as alleged." Id.

Merrell appealed the ALJ's decision to the Board. He
argued that under NTSB precedent, a pilot cannot be held
responsible for an inadvertent deviation caused by ATC error.
His had been such a deviation, he contended, because he had

__________
1 Merrell was also charged with "operat[ing] an aircraft in a
careless manner so as to endanger the lives or property of others,"
in violation of 14 C.F.R. s 91.13(a). As discussed infra note 23,
both parties appear to believe that the validity of this charge
depends wholly upon the validity of the s 91.123 charges.

taken actions which, but for ATC, would have kept him from
leaving his assigned altitude. He reasoned that because ATC
controllers are required to correct erroneous readbacks,2 his
construction of ATC's silence as tacit confirmation had been
reasonable and justified. In response, the FAA again argued
that because the primary cause of the deviation had been
Merrell's misperception of a clear instruction, his actions had
violated the safety regulations. The FAA maintained that
this outcome was consistent with Board precedent which, it
contended, absolves pilots only when "ATC error is the
initiating or primary cause of the deviation." R. at 321.

The NTSB accepted Merrell's arguments and dismissed the
enforcement order. It found that Merrell had made only "an
error of perception," and that there was "no evidence in the
record ... that [he] ... was performing his duties in a
careless or otherwise unprofessional manner." J.A. at 34. A
"perception mistake," the Board said, does not always result
from "a failure of attention," and therefore "careless inatten-
tion ... will not be automatically assumed in every case" in
which a pilot mishears ATC instructions. Id. Moreover,
there was no "failure of procedure" on Merrell's part, as he
had "made a full readback so that the opportunity was there,
absent the squelched transmission, for ATC to correct his
error." Id. at 35.

The FAA then petitioned the Board for reconsideration of
its decision. R. at 360-81. The agency argued that the
Federal Aviation Act requires the Board to defer to the
FAA's reasonable interpretation of its own safety regulations.
In the FAA's view, 14 C.F.R. s 91.123 obligates pilots "to
listen, hear, and comply with all ATC instructions except in
an emergency." Id. at 366; see id. at 362. "Inattention,
carelessness, or an unexplained misunderstanding," it said,
"do not excuse a deviation from a clearly transmitted clear-
ance or instruction." Id. at 367. "When there is an 'error of

__________
2 The handbook of ATC rules and procedures states: "If altitude,
heading or other items are read back by the pilot, ensure the
readback is correct. If incorrect or incomplete, make corrections as
appropriate." Federal Aviation Admin., U.S. Dep't of Transp., Air
Traffic Control p 2-72 (1993) [hereinafter ATC Procedures].

perception' resulting in a deviation, inattentiveness or care-
lessness are imputed in the absence of some reasonable
explanation for the failure to comply with the ATC clear-
ance." Id. According to the FAA, reasonable explanations
include events such as "radio malfunction" or a controller
error that precipitates a misunderstanding, but "[t]o excuse
[Merrell's] deviation in these circumstances as an acceptable,
though unexplained, 'error of perception' " would be inconsis-
tent with the agency's construction of s 91.123. Id. at 368-
69; see id. at 369, 371. Moreover, the FAA argued that the
Board's decision would have a "profound" negative effect on
air safety: "Under the decision, airmen can claim, without
further proof, that they did not hear or that they misper-
ceived safety crucial instructions as a means to avoid respon-
sibility for noncompliance or erroneous compliance with ATC
clearances and instructions." Id. at 374.

The Board denied the petition for reconsideration. Al-
though it acknowledged its "general obligation to defer to the
FAA's validly adopted interpretation of its regulations," the
Board considered itself under no such obligation in this case
because "the FAA cites no rule it has adopted that stands for
the proposition the FAA urges here." J.A. at 38. The Board
further noted that the FAA offered "no evidence of any policy
guidance written by the FAA, validly adopted or otherwise,"
to support its interpretation, and instead offered only "[c]oun-
sel's litigation statements." Id.

Because the Board determined that it was not required to
defer to the FAA's interpretation, it followed its own view of
appropriate aviation policy. It stated:

We ... disagree with the FAA's underlying belief that
our policy threatens aviation safety. The premise of our
approach is this--human beings make mistakes, and
there is no regulatory action, remedial or otherwise, that
can eliminate all mistakes.... [W]here an inevitable
error of perception does occur, the pilot should not face
sanction if he has acted responsibly and prudently there-
after....

Id. Adhering to this principle, the NTSB announced the
following rule:

 If a pilot makes a mistake and mishears a clearance or
ATC direction, follows all prudent procedures that would
expose the mistake (e.g., reads back the clearance), and
then acts on that mistaken understanding having heard
no correction from ATC, the regulatory violation will be
excused if that mistake is not shown to be a result of
carelessness or purposeful failure of some sort.

Id. at 37. The FAA then petitioned for review in this court.

B

Under the Federal Aviation Act's split-enforcement regime,
Congress has delegated rulemaking authority to the FAA:
"The Administrator of the Federal Aviation Administration
shall promote safe flight of civil aircraft in air commerce" by
prescribing, among other things, "regulations and minimum
standards for ... practices, methods, and procedure the
[FAA] finds necessary for safety in air commerce and nation-
al security." 49 U.S.C. s 44701(a). Pursuant to that authori-
ty, the FAA promulgated the safety regulations at issue here,
49 C.F.R. ss 91.123(b), (e). Congress has also given the
FAA authority to enforce its regulations through a number of
methods, including the issuance of "an order amending, modi-
fying, suspending, or revoking" a pilot's certificate if the
public interest so requires. 49 U.S.C. s 44709(b). The FAA
exercised that authority in issuing its enforcement order to
Captain Merrell. See J.A. at 7.

Congress has assigned adjudicatory authority under this
regime to the NTSB. See generally 49 U.S.C. s 1133. A
pilot whose certificate is adversely affected by an FAA en-
forcement order may appeal the order to the NTSB. See id.
s 44709(d)(1). Such an appeal is initially heard by an ALJ,
see 49 C.F.R. s 821.35(a), whose final decision may be appeal-
ed to the full Board, see id. s 821.47(a). The Board's deci-
sion, in turn, may be reconsidered upon the petition of either
party. See id. s 821.50. In reviewing an FAA order, "the
Board is not bound by findings of fact of the [FAA] Adminis-
trator." 49 U.S.C. s 44709(d)(3). It is, however, "bound by
all validly adopted interpretations of laws and regulations the

Administrator carries out ... unless the Board finds an
interpretation is arbitrary, capricious, or otherwise not ac-
cording to law." Id.

If dissatisfied with a final order of the Board, either the
FAA Administrator or any "person substantially affected"
may petition for review in this court. Id. ss 1153(c), 44709(f),
46110.3 On judicial review, the "[f]indings of fact of the
Board are conclusive if supported by substantial evidence."
49 U.S.C. s 44709(f); id. s 1153(c); see also id. s 46110(c).
We must, however, set aside Board decisions if they are
"arbitrary, capricious, an abuse of discretion, or otherwise not
in accordance with law." 5 U.S.C. s 706(2)(A).4 And, like
the NTSB, we must defer to the FAA's interpretations of its
own aviation regulations. Cf. Martin v. Occupational Safety
& Health Review Comm'n, 499 U.S. 144, 147, 150-57 (1991)
(holding that courts must defer to interpretations of Secre-
tary of Labor rather than to those of OSHRC in split-
enforcement regime under Occupational Safety & Health
Act).

II

As we have just described, Congress has "unambiguously
direct[ed] the NTSB to defer to the FAA's interpretations of

__________
3 Although this case is styled Administrator, FAA v. NTSB, the
real parties in interest are the FAA and Captain Merrell. The
situation is roughly analogous to an appeal from a district court:
the NTSB (the adjudicator below) "has no direct stake in the
outcome" and therefore does not have any role "as a party in
judicial review proceedings." Hinson, 57 F.3d at 1147 n.1.

4 See generally Martin v. Occupational Safety & Health Review
Comm'n, 499 U.S. 144, 158 (1991); Hinson, 57 F.3d at 1149-50;
Public Citizen, Inc. v. FAA, 988 F.2d 186, 196-97 (D.C. Cir. 1993).
Prior to 1994, the text of the Federal Aviation Act mandated that
judicial review of NTSB orders "be conducted in accordance with
the provisions of" the Administrative Procedure Act (APA), includ-
ing 5 U.S.C. s 706(2)(A). See 49 U.S.C. s 1903(d) (1994) (repealed
1994). In 1994, this provision was "omitted as unnecessary because
[the APA] applies by its own terms." H.R. Rep No. 103-180, at 18
(1993).

its own regulations." Hinson, 57 F.3d at 1148 n.2 (citing 49
U.S.C. s 44709(d)(3)); see also id. at 1151. Here, however,
the NTSB explicitly declined to defer to the agency's inter-
pretation of 14 C.F.R. s 91.123. In this Part, we consider the
argument that deference to the FAA was not required, either
because its interpretation was not validly adopted or because
that interpretation was really a factual finding in disguise.

A

The NTSB declined to defer to the FAA primarily because
the agency had offered "no evidence of any policy guidance
written by the FAA, validly adopted or otherwise," to support
its interpretation. J.A. at 38. Instead, the agency had
merely offered the "litigation statements" of FAA counsel, as
well as citations to the Board's own case law. See id. The
NTSB believed the former insufficient to qualify for Board
deference under section 44709(d)(3). Accordingly, it rejected
the FAA's interpretation and expressly adopted its own policy
to govern cases like that of Captain Merrell.

The NTSB's refusal to defer to the FAA on this question of
regulatory interpretation and air safety policy was error.
The FAA is not required to promulgate interpretations
through rulemaking or the issuance of policy guidances, but
may instead do so through litigation before the NTSB. We
have said as much before,5 and the Supreme Court so held in
Martin v. Occupational Safety & Health Review Comm'n
with respect to the similar split-enforcement regime of the
Occupational Safety & Health Act.6 Indeed, the NTSB itself

__________
5 See Hinson, 57 F.3d at 1148-49, 1151 (stating that the FAA
could assert its interpretations in litigation before the NTSB and
that "the Board would then be required to defer").

6 See Martin, 499 U.S. at 157-58 (holding that "the Secretary's
litigating position before the Commission is as much an exercise of
delegated lawmaking powers as is the Secretary's promulgation of a
workplace health and safety standard," and that "the Secretary's
interpretation is not undeserving of deference merely because the
Secretary advances it for the first time in an administrative adjudi-
cation").

has repeatedly made the same point.7 The fact that this
mode of regulatory interpretation necessarily is advanced
through the "litigation statements" of counsel does not relieve
the NTSB of its statutory obligation to accord it due defer-
ence.8

__________
7 See Petition of Quintana, NTSB Order No. EA-3737 (1992),
1992 WL 362084, at *2 (noting that NTSB has previously recog-
nized "that rule interpretation may occur through adjudication");
id. at *3 (noting that the NTSB has "adopted and followed the
principles discussed in Martin v. OSHRC"); see also Petition of
Van Eaton, NTSB Order No. EA-4692 (1998), 1998 WL 546384, at
*2 ("The FAA is entitled to make policy via adjudication. In such a
case, the question for us would be whether the proposed policy
conforms with the words of the regulation."); Administrator v.
Miller, NTSB Order No. EA-3581 (1992), 1992 WL 137750, at *2-4
("While the evolutionary interpretation of rules is thought to be
better accomplished through the rulemaking process itself, there is
little question that the adjudicatory process may also be used to
develop and define the meaning of existing regulations.").

8 In Martin, the Supreme Court rejected the contention that
according deference to agency litigating positions taken before an
administrative adjudicator would be inconsistent with the Court's
prior holdings denying deference to litigating positions taken upon
judicial review:

Our decisions indicate that agency "litigating positions" are not
entitled to deference when they are merely appellate counsel's
"post hoc rationalizations" for agency action, advanced for the
first time in the reviewing court. Because statutory and
regulatory interpretations furnished in this setting occur after
agency proceedings have terminated, they do not constitute an
exercise of the agency's delegated lawmaking powers. The
Secretary's interpretation of OSH Act regulations in an admin-
istrative adjudication, however, is agency action, not a post hoc
rationalization of it.

499 U.S. at 156-57 (citations omitted). In this case, it is particular-
ly clear that the FAA's position is not simply that of its litigators,
because after the agency instituted this enforcement action, it
published its interpretation of s 91.123 in the form of an interpre-
tive rule. See 64 Fed. Reg. 15,912 (1999).

Nor was Merrell's the first case in which the FAA inter-
preted its regulations as it does here. The position the
agency took in its petition for reconsideration can be summa-
rized as follows: Failure to understand an ATC instruction is
a valid defense to a section 91.123 charge only if the pilot
provides some exculpatory explanation, such as radio mal-
function or precipitating controller error. See R. at 371.
That is precisely the position the FAA took before this court
in Hinson--although there we refused to consider it because
the agency had failed to raise it below. See Hinson, 57 F.3d
at 1150-51. It is also the position the FAA has consistently
taken in litigation before the Board. See Administrator v.
Gentile, 6 N.T.S.B. 60, 64 (1988); Administrator v. Wells, 1
N.T.S.B. 1472, 1474 (1971). As discussed in Part IV, while
the NTSB's own position has wavered over the years, the
FAA's has not.

In sum, the NTSB's rationale for denying deference to the
FAA's interpretation of 14 C.F.R. s 91.123 was unjustified.

B

Merrell offers another potential justification for the
NTSB's failure to defer to the FAA. The FAA's position
below was not truly an "interpretation," he argues, but rather
a determination of fact with which the Board was free to
disagree. As Merrell observes, the FAA's petition for recon-
sideration states: "When there is an 'error of perception'
resulting in a deviation, inattentiveness or carelessness are
imputed in the absence of some reasonable explanation...."
R. at 367. In addition, the FAA's appellate briefs consistent-
ly describe its interpretation as a presumption or inference.
See, e.g., FAA Br. at 23 ("FAA employs the following pre-
sumption: where evidence shows that a pilot mistakenly fails
to understand and comply with a clear and distinct ATC
transmission, and where the pilot fails to provide an exculpa-
tory explanation for his mistake, FAA presumes that the
pilot's mistake was due to inattention...."); see also id. ("[I]t
is fair and reasonable to infer that [Merrell's] mistake was
attributable to inattention...."). The FAA's decision to

"impute," "presume," or "infer" carelessness in a particular
situation, Merrell argues, "is nothing more than a finding of
fact, which can be reversed by the NTSB." Merrell Br. at 14.

We note first that Merrell did not make this argument
below, see Opp'n to Pet. for Recons., and that the NTSB did
not itself refuse to defer on the ground that the FAA's
interpretation was really a finding of fact. Even if we could
nonetheless consider the argument here, it is plain that the
FAA's decision to infer carelessness from unexplained error
does not represent a finding of fact in this, or any other,
particular case. To the contrary, the FAA's inference is
simply a justification for the regulatory interpretation the
agency applies in all cases--a rationale for why it is reason-
able to declare a violation when a pilot errs and has no
explanation for his error. Although the agency's rule does
act like a presumption, a presumption is a rule of law and not
a finding of fact. See W. Page Keeton et al., Prosser &
Keeton on the Law of Torts 240 (5th ed. 1984) ("There is ...
general agreement that presumptions are rules of law....").

A presumption is valid if it is rational. See Usery v.
Turner Elkhorn Mining Co., 428 U.S. 1, 28 (1976) (noting
that a presumption will be upheld if there is "some rational
connection between the fact proved and the ultimate fact
presumed, and [if] the inference of one fact from proof of
another shall not be so unreasonable as to be a purely
arbitrary mandate"); see also NLRB v. Baptist Hosp., 442
U.S. 773, 787 (1979); Chemical Mfrs. Ass'n v. Department of
Transp., 105 F.3d 702, 705-06 (D.C. Cir. 1997). And surely it
is rational to infer that a pilot was careless or inattentive if he
deviated from a clearance order without any explanation at
all. In this case, everyone who listened to the recording of
the ATC clearance instructions--including Captain Merrell--
confirmed that those instructions were clear and understand-
able. See J.A. at 14-15, 18-19; R. at 145. Merrell's state-
ment that he "misheard" the transmission is not an explana-
tion for his deviation, but rather a concession that he has no
explanation. Under such circumstances, it is not unreason-
able to presume that he simply was not listening closely
enough. Such a presumption is as common-sense as that

employed in tort cases that hold that the running of a red
light creates a presumption of negligence, rebuttable only by
an exculpatory justification (such as brake failure).9

There is also no merit to Merrell's contention that the
FAA's presumption impermissibly reverses the burden of
proof in NTSB proceedings--a point upon which, again, the
Board did not rely. FAA regulations mandate that "[i]n
proceedings under [49 U.S.C. s 44709], the burden of proof
shall be upon the Administrator." 49 C.F.R. s 821.32. Mer-
rell contends that the FAA's interpretation of section 91.123
is in reality an attempt to circumvent this evidentiary require-
ment. He asserts that "[h]aving failed to carry its burden of
proof," the FAA "sought to eliminate that burden by invent-
ing a legal 'interpretation.' " Merrell Br. at 15. The Su-
preme Court considered a similar contention in Director v.
Greenwich Collieries, 512 U.S. 267 (1994). There, the Court
construed s 7(c) of the Administrative Procedure Act (APA),
5 U.S.C. s 556(d), which imposes the "burden of proof" on the
proponent of an order. The Court held that the phrase
should be understood as having its "ordinary or natural
meaning," which, it said, was the burden of persuasion. 512
U.S. at 272, 276. Because the Labor Department rule at
issue in Greenwich (the so-called "true doubt" rule) reversed
the persuasion burden, the Court struck it down. See id. at
280-81. It indicated, however, that a presumption that did
not shift the burden of persuasion would be acceptable under
the APA because it would not affect the "burden of proof."
Id. at 280. In accordance with this reasoning, every Circuit
that has considered the issue since has concluded that a
presumption that shifts only the burden of production does
not shift the "burden of proof" as that phrase is used in the
APA. See Gulf & W. Indus. v. Ling, 176 F.3d 226, 232-34
(4th Cir. 1999); Glen Coal Co. v. Seals, 147 F.3d 502, 510-13
(6th Cir. 1998); Lovilia Coal Co. v. Harvey, 109 F.3d 445, 452

__________
9 See, e.g., Byrne v. City & County of S.F., 113 Cal.App.3d 731,
740-41 (Cal. Ct. App. 1980); deJesus v. Seaboard Coast Line R.R.
Co., 281 So.2d 198, 201 (Fla. 1973); Piatt v. Welch, 974 S.W.2d 786,
788 (Tx. App. 1998). See generally Keeton et al., supra, at 230-31
& n.12.

(8th Cir. 1997). Merrell offers no reason to read the same
phrase in section 821.32 any differently.

On this analysis, the FAA presumption at issue here is
permissible if it shifts only the burden of production--and it
does. That is the typical role of presumptions in modern
evidence law,10 and the FAA's description of its presumption
indicates that it functions in the same manner. That is, once
the FAA shows that a pilot failed to follow a clear ATC
instruction, the burden of production shifts to the pilot to
offer an exculpatory explanation.11 Accordingly, we find no
warrant for regarding the FAA's interpretation as the equiva-
lent of a finding of fact or for concluding that it reverses the
FAA's burden of proof, and hence no warrant for the NTSB's
refusal to pay it appropriate deference.

III

Deference, of course, does not mean blind obedience. The
agency's interpretation still must not be "plainly erroneous or
inconsistent with the regulation" it is interpreting. Cassell v.
FCC, 154 F.3d 478, 484 (D.C. Cir. 1998) (quoting Auer v.
Robbins, 519 U.S. 452, 461 (1997)). And even if the interpre-
tation meets this standard, the NTSB need not follow it if it

__________
10 See Fed. R. Evid. 301 ("[A] presumption imposes on the party
against whom it is directed the burden of going forward with
evidence to rebut or meet the presumption, but does not shift to
such party the burden of proof in the sense of the risk of nonper-
suasion....").

11 See FAA Br. at 23 ("FAA employs the following presumption:
where evidence shows that a pilot mistakenly fails to understand
and comply with a clear and distinct ATC transmission, and where
the pilot fails to provide an exculpatory explanation for his mis-
take, FAA presumes that the pilot's mistake was due to inatten-
tion....") (emphasis added). Compare FAA Pet. for Recons., R. at
371 (characterizing proof that deviation from ATC instruction oc-
curred as establishing "prima facie case"), with Thomas v. National
Football League Players Ass'n, 131 F.3d 198, 202 (D.C. Cir. 1998)
(holding that proof of prima facie case of discrimination under Title
VII creates rebuttable presumption that shifts burden of production
but not burden of persuasion).

"is arbitrary, capricious, or otherwise not according to law."
49 U.S.C. s 44709(d)(3). We consider these two standards
below.

First, we examine whether the FAA's interpretation was a
reasonable construction of its regulation. The two subsec-
tions of section 91.123 that Merrell was charged with violating
state:

(b) Except in an emergency, no person may operate an
aircraft contrary to an ATC instruction in an area in
which air traffic control is exercised.

....

(e) Unless otherwise authorized by ATC, no person oper-
ating an aircraft may operate that aircraft according to
any clearance or instruction that has been issued to the
pilot of another aircraft for radar air traffic control
purposes.

14 C.F.R. s 91.123.

Under the FAA's interpretation, a pilot who flies contrary
to either of these commands is in violation unless he has an
exculpatory explanation, such as "radio malfunction" or "ATC
error resulting in a faulty transmission that precipitates a
misunderstanding." FAA Br. at 15. This interpretation is
consistent with the regulation. Indeed, the one respect in
which it varies actually favors the pilot: it adds two excep-
tions (radio malfunction and precipitating ATC error) to the
only two expressly listed in the rule itself (emergency and
ATC authorization)--apparently because the FAA believes
they are fairly implied. None of these exceptions assists
Merrell, however, who has offered no explanation whatsoever
for his failure to understand the clear and distinct ATC
transmission. The FAA has also indicated, as a matter of its
enforcement discretion, that in cases where ATC could have
corrected a pilot's misunderstanding but did not, the agency
will waive or reduce the sanctions for the violation (although
it will still declare that the violation occurred). See id. at 18.
Again, this offers Merrell no assistance, as it is undisputed
that ATC could not have corrected Merrell's error, and in any

event, the FAA has in fact waived any possible sanctions
against him. We therefore find that the FAA's construction
is a reasonable interpretation of its regulation, and that
Merrell's case fits comfortably within that interpretation.

Second, we must determine whether the FAA's policy, as
expressed in its interpretation, is arbitrary, capricious, or
otherwise not in accordance with law. There is no question
that the FAA's policy is harsh, but that does not make it
unreasonable. The FAA contends that the rule's strictness is
required by the potentially catastrophic consequences of non-
compliance with ATC transmissions. In the agency's view,
the only way to prevent air disasters is to ensure "that pilots
exercise unflagging diligence in monitoring, understanding,
and obeying clearly transmitted ATC instructions." Id. at
16-17. And the best way to ensure such diligence, the FAA
has concluded, is to hold pilots to "an exacting standard of
accountability." Id. at 17.

To continue our earlier analogy, the FAA's approach is
somewhat akin to that of the motor vehicle safety laws.
Although a driver may be able to defend the running of a red
light on the ground of brake failure, the excuse that he simply
"did not see it" does not avoid a ticket. Following the same
logic, the FAA has concluded that while a radio malfunction
can excuse a pilot's deviation from an ATC instruction, the
claim that he simply "misheard it" does not. This approach is
both rational and consistent with the Federal Aviation Act,
which instructs the FAA to prescribe rules that, in its judg-
ment, "best tend[ ] to reduce or eliminate the possibility or
recurrence of accidents in air transportation." 49 U.S.C.
s 44701(c).

We recognize that the NTSB prefers a different approach,
one which might best be expressed, in the words of Alexander
Pope, as, "To err is human...." Alexander Pope, An Essay
on Criticism, in Collected Poems 58, 71 (Bonamy Dobree
ed., Everyman's Library 1983) (1711). The "premise" of its
approach, the Board states, is that "human beings make
mistakes, and there is no regulatory action, remedial or
otherwise, that can eliminate all mistakes." Order on Re-

cons., J.A. at 38. Hence, the Board maintains that "where an
inevitable error of perception does occur, the pilot should not
face sanction if he has acted responsibly and prudently there-
after...." Id. Although we cannot say that this view is
unreasonable, that is not the issue. The NTSB is bound to
follow the FAA's interpretation of a regulation unless the
Board finds it arbitrary, capricious, or otherwise unlawful.
See 49 U.S.C. s 44709(d)(3). It was not arbitrary or capri-
cious for the FAA to conclude that in the unforgiving environ-
ment of aviation, in which even good-faith error can lead to
tragedy, the best way to encourage pilot attentiveness is
through its harsh approach rather than the NTSB's more
lenient one. This conclusion is consistent with the governing
law, which makes clear that the FAA's principal responsibility
is not to protect the interests of pilots, but rather to ensure
that air carriers "provide service with the highest possible
degree of safety in the public interest." Id. s 44701.

Finally, we consider Merrell's argument that the FAA's
interpretation of subsections (b) and (e) of section 91.123 is
arbitrary because it conflicts with readback procedures as-
sertedly contained in subsection (a) of the same section. The
FAA's position, Merrell stresses, means that "a pilot who
inadvertently mishears a clearance, reads it back to the
controller to check his understanding, and receives no correc-
tion from the controller, would nevertheless be liable for a
violation of s 91.123" barring an exculpatory explanation for
the initial misunderstanding. Merrell Br. at 19. Yet, he
continues, subsection 91.123(a) states that a pilot who is
"uncertain" about a clearance must "immediately request
clarification from ATC." Id. at 20 (quoting 14 C.F.R.
s 91.123(a)). That request, according to Merrell, "is made
through a readback, and the written procedures governing air
traffic controllers obligate controllers to correct any errors in
the readback." Merrell Br. at 20; see supra note 2. Because
of that obligation, Merrell argues, pilots are entitled to take
ATC silence as acknowledgment that their readback was
correct. Moreover, he contends that if the FAA's position
were accepted, "s 91.123(a) would be superfluous" because a
pilot uncertain about a clearance "could follow the instruction

of s 91.123(a) precisely, but nevertheless be liable for violat-
ing s 91.123(b) if ATC improperly failed, either because of
human or system error, to respond to the pilot's recitation of
an incorrect clearance." Merrell Br. at 20.

There is no conflict between the FAA's interpretation of
subsections 91.123(b) and (e) and the language of section
91.123(a). The latter provision refers to "clarification[s]," not
readbacks, and the two are not the same. A request for
clarification--which is mandatory when a pilot is "uncertain"
about his clearance--requires ATC to transmit an affirmative
clarifying response. If ATC fails to provide one, the pilot
must renew his request until one is forthcoming. See 14
C.F.R. s 91.123(a); FAA Reply Br. at 7-8. A readback, by
contrast, is a non-mandatory acknowledgment by the pilot
which, if correct, does not require an affirmative response
from the controller. See ATC Procedures p 2-72; 64 Fed.
Reg. 15,912, 15,913 (1999). The clarification procedure is not
implicated in the current case, as Merrell does not contend he
was uncertain about the ATC instruction.

Nor is the FAA's interpretation either inconsistent with, or
rendered irrational by, what Merrell contends is the routine
pilot practice of reading back clearances and taking ATC
silence as acknowledgment of accuracy. "Readbacks," the
FAA points out, "add a layer of safety redundancy." FAA
Reply Br. at 8. If a pilot transmits a readback, ATC will
usually be able to correct a misunderstanding even if the pilot
himself did not realize there was one. But as this case shows,
the readback procedure is not failsafe; there is no guarantee
that ATC's silence means it has received and confirmed the
pilot's transmission. This underscores the reasonableness of
the FAA's policy, which requires pilots to perceive ATC
instructions correctly and not to depend upon the potentially
unreliable readback mechanism. See id. at 8, 17.12

__________
12 Although the FAA could make full readbacks mandatory and
require pilots to await confirmation before proceeding, the agency
has concluded that such a policy would disserve air safety by
congesting radio frequencies. See 64 Fed. Reg. 15,913 (1999).
Neither we nor the NTSB may second-guess that policy determina-

 IV

In support of the decision below, Merrell argues that the
NTSB's holding is "thoroughly consistent with a well-
established line of Board precedent." Merrell Br. at 17. The
FAA contends that the opposite is true. As we discuss in this
Part, the situation is far less clear than either party is willing
to concede. But even if Merrell were correct, the fact that
the Board followed its own precedent would not be a suffi-
cient basis on which to uphold its decision. Because the FAA
is entitled to launch new policies through administrative
adjudication, it may sometimes be necessary for the NTSB to
accommodate such policies by changing its jurisprudential
course.

We begin by noting that there are actually two divergent
lines of NTSB precedent in this area.13 One line contradicts
Merrell's position, holding that if a pilot deviates from an
ATC instruction in the absence of an emergency, the pilot is
in violation unless an external factor precipitated the error.14

__________
tion. Merrell also suggests that the FAA could require the installa-
tion of technology "that would eliminate the problem at the root of
this case: blocked radio transmissions." Merrell Br. at 21-22.
Because this was not a part of the NTSB's rationale for rejecting
the FAA's interpretation, we may not rely upon it here. See
Cassell, 154 F.3d at 483 n.5.

13 The NTSB came close to acknowledging this point in its Order
on Reconsideration. See J.A. at 38 ("As a principle of administra-
tive law, we may modify our precedent.... We have done so over
time with regard to this issue, with the FAA often in disagree-
ment.").

14 See Administrator v. Swafford & Coleman, NTSB Order No.
EA-4117 (1994), 1994 WL 108069, at *2 (holding that although
"precedent recognizes that when ATC error is the initiating or
primary cause of the deviation, the complaint will be dismissed,"
that is not the case where "the ground controller's instructions to
[the pilot] were clear and unambiguous"); Administrator v. Wolfen-
barger, NTSB Order No. EA-3684 (1992), 1992 WL 289055, at *3
(ruling that "the only regulatory exception to compliance with an
[ATC] instruction is in-flight radio malfunction" and that pilot's
claim he did not hear ATC instruction was therefore "irrelevant");

Under this line of cases, when the pilot cannot point to such a
precipitating factor, the NTSB attributes the error to the
pilot's own lack of care. And under this line, a violation is not
excused even if the pilot reads back the misunderstood in-
struction and ATC fails to correct it, notwithstanding its
ability to do so.15

The second line of NTSB precedent, that cited by Merrell,
is more supportive of his position although not wholly sup-
portive. Under this line, the Board will excuse a pilot's
deviation if ATC error was a contributing cause.16 In the

__________

Administrator v. Gentile, 6 N.T.S.B. 60 (1988) (holding that "it is
patent that deviation from an altitude clearance in positive control
airspace is careless in the absence of an emergency or some other
extenuating circumstances"); Administrator v. Nelson & Keegan, 2
N.T.S.B. 1900 (1975) (concluding that "the most reasonable explana-
tion for respondents' following instructions issued to another flight"
was that "respondents did not exercise the highest degree of care
expected of airline pilots," and that regulatory violation was not
excused by fact that "controller might have taken additional mea-
sures which could have averted a deviation of the magnitude that
occurred"); Administrator v. Wells, 1 N.T.S.B. 1472 (1971) ("Inas-
much as the altitude restriction was transmitted ... twice, both
times in clear terms, [the pilot's] failure to hear the clearance, and
adhere to it, can only be attributed to carelessness on his part.").

15 See Swafford & Coleman, 1994 WL 108069, at *2. While the
Board will not dismiss the violation under such circumstances, it will
mitigate sanctions. See id. at *3; see also Nelson & Keegan, 2
N.T.S.B. at 1900 (stating that system imperfections and contribut-
ing controller error are "more appropriately given weight as miti-
gating circumstances" rather than as excuses for violations). As
previously noted, the FAA waived sanctions altogether in Merrell's
case.

16 See Administrator v. Jackson, NTSB Order No. EA-4381
(1995), 1994 WL 804033, at *3 n.11 ("Our precedent holds that,
'even if a deviation from a clearance is initiated by an inadvertent
mistake on the pilot's part, that mistake will be excused and no
violation will be found if, after the mistake, the pilot takes action
that, but for ATC, would have exposed the error and allowed for it
to be corrected.' ") (quoting Administrator v. Atkins & Richards,

typical case, a pilot misunderstands a clear ATC instruction,
the pilot gives a readback that reflects this misunderstanding,
and ATC receives the erroneous readback but fails to correct
the error despite its ability to do so. The cases Merrell cites
indicate the NTSB will exonerate pilots who deviate from
ATC instructions under such circumstances. The underlying
rationale of these cases, however, appears to be that ATC
could have corrected the pilot's misunderstanding before a
violation occurred. See cases cited supra note 16.17 Indeed,
the only precedent the NTSB itself cited in rejecting the
FAA's petition for reconsideration, Administrator v. Froh-
muth & Dworak, was a case in which the Board excused a
violation because ATC, and not the pilot, was responsible for
the initial misunderstanding.18 Here, ATC was neither re-
sponsible for the initial misunderstanding nor capable of
correcting it since it never received Merrell's readback.

More important, even if the NTSB had followed an unvary-
ing line contrary to the regulatory interpretation the FAA
advances here, that would not be sufficient to uphold the
Board's decision in this case. As we noted at the outset, the
interpretation of air safety regulations is an area in which the
Board owes deference to the FAA. For that reason, consis-

__________
NTSB Order No. EA-4078 (1994), 1994 WL 49589, at *2) (emphasis
added); Administrator v. Shields, NTSB Order No. EA-4180
(1994), 1994 WL 267742, at *1 (suggesting that pilot would have
defense if "ATC should have caught the mistake"); Administrator
v. Holstein, 6 N.T.S.B. 569 (1988) (dismissing order "under unique
circumstances" where ATC "either did not hear the miscommunica-
tion or was confused by it").

17 The NTSB administrative law judge in Merrell's case read
these cases the same way. See J.A. at 26 ("In all of the cases where
the board has absolved these pilots of some responsibility, the
circumstances have been that that responsibility has somehow been
put back onto air traffic control....").

18 See Administrator v. Frohmuth & Dworak, NTSB Order No.
EA-3816 (1993), 1993 WL 75479, at *2 (observing that pilot error at
issue was "apparently induced ... by ATC's actions" because ATC
had "not clearly separated" instructions to Frohmuth's aircraft from
those to another plane with similar call sign) (emphasis added).

tency with the FAA's position is more important than consis-
tency with the Board's own. As both the NTSB and Merrell
concede, the FAA is authorized to initiate new regulatory
interpretations through adjudication.19 And because the
Board is bound to follow such interpretations, it may at times
be both necessary and proper for the Board to depart from
its prior case law.20

As discussed in Part II.A, the position the FAA takes here
is neither new nor inconsistent with its previous view of a
pilot's obligations. Nonetheless, there are still some con-
straints on the FAA's ability to bend the NTSB to its will in
this case. For one, if a rule is to be applied to a regulated
party, that party must have received fair notice. See United
States v. Chrysler Corp., 158 F.3d 1350, 1354 (D.C. Cir. 1998);
General Elec. Co. v. EPA, 53 F.3d 1324, 1328-29 (D.C. Cir.
1995); see also Martin, 499 U.S. at 158 (noting that decision
to use adjudication "as the initial means for announcing a
particular interpretation may bear on the adequacy of notice
to regulated parties"). In this case, however, there was fair
notice. The plain language of section 91.123 states that a

__________
19 See Petition of Van Eaton, 1998 WL 546384, at *3 (acknowl-
edging FAA's prerogative to advance regulatory interpretation
through administrative adjudication even where such interpreta-
tion "amend[s]" the agency's prior approach); Petition of Quinta-
na, 1992 WL 362084, at *4-5 (deferring to FAA interpretation
"offered officially for the first time in this proceeding" and not
inconsistent "with the words of the rule or with [the Administra-
tor's] past position"); Miller, 1992 WL 137750, at *2-5 (deferring
to FAA interpretation "now offered for the first time [but] not
inconsistent with any prior interpretative pronouncements"); Mer-
rell Br. at 16 (citing Miller as case in which "Board deferred to
FAA interpretation of regulation, asserted for the first time in
enforcement proceedings"). Cf. Martin, 499 U.S. at 158 ("[T]he
Secretary's interpretation is not undeserving of deference merely
because the Secretary advances it for the first time in an adminis-
trative adjudication.").

20 See Hinson, 57 F.3d at 1149-50 ("Nor is the Board irrevocably
bound to its own precedents, so long as it gives a reasoned
explanation for its departure.").

pilot must follow ATC directions unless there is an emergen-
cy, and does not suggest that he may rely on readback
procedures to absolve himself of responsibility.

An agency is also barred from applying a new rule in the
adjudication in which it is announced if doing so would work a
"manifest injustice." Cassell, 154 F.3d at 486-87 (quoting
Clark-Cowlitz Joint Operating Agency v. FERC, 826 F.2d
1074, 1081 (D.C. Cir. 1987)).21 In cases like this one, the issue
boils down to the question of whether the regulated party
reasonably and detrimentally relied on a previously estab-
lished rule. See id. at 486. For the reasons discussed above,
however, there was no established, contrary rule upon which
Merrell could have relied. Again, the FAA's position on this
matter has been unwavering, while the NTSB's position has
been at most internally inconsistent. Nor does Merrell sug-
gest that there is anything he would have done differently as
a pilot had he known how the FAA would interpret its rule.22
Accordingly, the NTSB's precedent in this area is insufficient
to render the application of the FAA's interpretation to
Merrell a "manifest injustice."

V

Finally, Merrell complains that the FAA did not begin to
characterize its position as a regulatory interpretation until
its petition for reconsideration. Both before the ALJ and
initially before the Board, Merrell contends, FAA counsel
presented the case as a straightforward charge of factual
carelessness. But the NTSB did not refuse to consider the
FAA's interpretation argument on the ground of tardy pre-
sentation, and Merrell himself stops short of contending that
the agency's tardiness should have barred it from making the

__________
21 In addition, the agency must (among other things) explain its
change of course, and the new course must be neither arbitrary nor
capricious. See Motor Vehicle Mfrs. Ass'n v. State Farm Mut.
Auto. Ins. Co., 463 U.S. 29 (1983); Hinson, 57 F.3d at 1149-50.

22 To the contrary, Merrell contends that "[n]o matter what
happens" in this case, pilots will continue their current practices.
Merrell Br. at 21.

argument, saying only that the point is "worth noting." Mer-
rell Br. at 14. He does, however, strongly suggest that the
FAA pursued an unfair strategy by shifting to a second
theory after losing on the first. Three considerations lead us
to conclude that the FAA's delay should not affect our
disposition of this case.

First, it is true that the FAA did not initially argue that it
interpreted its regulation to presume inattentiveness or care-
lessness in the absence of explanation; nor did it initially
argue that the NTSB was required to defer to such an
interpretation. On the other hand, the FAA also did not
appear to limit itself solely to a claim of factual carelessness.
For example, during the initial hearing before the ALJ, the
FAA's counsel argued: "The Board has stated that an alti-
tude deviation in positive control airspace ... is carelessness
in the absence of an emergency." R. at 201. Counsel also
argued that pilots should be found in violation of section
91.123 whenever their errors were not initiated by external
factors. See id. at 200, 213-14. These arguments are consis-
tent with the position the FAA took on reconsideration.
They suggest that the FAA's litigating posture was not so
much strategic as simply muddled.

Second, we are not precluded from considering a regulatory
interpretation simply because the FAA raised it for the first
time in a petition for reconsideration below--at least not
where, as here, the Board went on to consider and resolve the
petition on the merits. The pertinent statute states that "the
court may consider an objection to an order of the Board only
if the objection was made in the proceeding conducted by the
Board or if there was a reasonable ground for not making the
objection in the proceeding." 49 U.S.C. s 1153(b)(4); see
also id. s 46110(d). The reconsideration process qualifies as
a proceeding conducted by the Board. See 49 C.F.R.
s 821.50. Indeed, although in Hinson we rejected the FAA's
effort to advance its regulatory interpretation because the
agency had not raised it at all in the NTSB proceedings, we
indicated we would have considered it had the FAA raised it
at the reconsideration stage. See Hinson, 57 F.3d at 1148-
49, 1150-51.

 Third, and most important, Merrell does not suggest any
way in which the late emergence of the FAA's interpretation
argument prejudiced him. He does not contend, for instance,
that if he had known of the argument earlier he would have
litigated the factual issues differently. To the contrary, since
Merrell construed the charge against him as one of pure
factual carelessness, he had every reason to offer an explana-
tion for his misperception of the ATC instructions at the
initial hearing. And as he concedes he had no explanation,
there was no further evidence he could have produced, re-
gardless of how he understood the charge. Nor was Merrell
disadvantaged in arguing the legal issues. After the FAA
articulated its position in its petition for reconsideration,
Merrell had a full opportunity to respond in opposition to the
petition, and he did so. See R. at 382-92.

None of this excuses the FAA's failure to be clear about its
position from the start. Given that the agency lost Hinson in
part because it failed to raise its interpretation argument in a
timely manner, one would think it would have taken care not
to wait until the last possible moment to raise the argument
this time around. Employing the same presumption the FAA
applies to pilots, we would have to conclude that only the
agency's "inattentiveness" explains its tardiness. But unlike
a pilot, the agency--and, derivatively, the flying public--
cannot be sanctioned for its inattentiveness through dismissal
of the enforcement order issued in this case.

VI

Because the NTSB failed to defer to the FAA's reasonable
interpretation of its own regulations, we conclude that the
Board's ruling was not in accordance with law. We therefore
grant the petition for review, reverse the Board's decision,
and remand the case for further proceedings consistent with
this opinion.23

__________
23 As noted supra note 1, Merrell was also charged with "oper-
at[ing] an aircraft in a careless or reckless manner so as to
endanger the life or property of another," in violation of 14 C.F.R.
s 91.13(a). On its face, s 91.13(a) could be read to require a

---------

Note 23--Continued
different standard of care than s 91.123, since only the former
expressly uses the term "careless." Nonetheless, Merrell makes no
argument concerning s 91.13(a), apparently assuming that--as the
FAA asserts--a s 91.13(a) violation can be wholly derivative of a
s 91.123 violation. See FAA Br. at 5 n.1 (citing Jackson v. NTSB,
114 F.3d 283, 287 (D.C. Cir. 1997) (noting NTSB decision character-
izing s 91.13(a) violation as "residual or derivative" of s 91.123
violation)); see also Administrator v. Clark, 7 N.T.S.B. 434, 436
(1990) (holding s 91.13(a) derivative of s 91.123); Administrator v.
Buller, 6 N.T.S.B. 31, 32 (1988) (same). Accordingly, we reverse
without addressing whether the standard of care under each of
these regulations might be different.