Opinion for the Court filed by Chief Judge SENTELLE.
Michael George Manin petitions for review of a National Transportation Safety Board (“NTSB” or “Board”) order affirming the Federal Aviation Administration’s (“FAA”) emergency revocation of his airline transport pilot, flight instructor, flight engineer, and first class airman medical certificates for failure to provide correct information about his criminal history on a series of applications for renewal of his medical certificate. Because the NTSB’s decision departed from agency precedent without explanation and was inconsistent with recent case law in this circuit, we vacate the Board’s order and remand for further proceedings consistent with this opinion.
I.
Petitioner Michael Manin had for several years before the events under review held various FAA certificates, including a first class airman medical certificate, which is a certification by a physician that the pilot meets medical standards for aircraft operation. A first class airman medical certificate must be renewed periodically: every year for pilots under the age of 40 and every six months for pilots aged 40 and older.
The application for renewal of this medical certificate includes questions regarding the applicant’s criminal history. The FAA revoked Manin’s airline transport pilot certificate and his medical certificate in 1994 for intentional falsification of a medical application, after discovering that he had failed to disclose a March 1992 conviction for making a false statement on a passport application. Manin made the proper disclosure on his next application and was issued a medical certificate in February 1995. He regularly applied for and received renewals of his certificate in succeeding years.
On December 14, 1995, Manin was convicted in the Barberton, Ohio, Municipal Court of disorderly conduct, which is classified as a “minor misdemeanor” under Barberton’s municipal code. He next applied for a medical certificate on June 1, 1996. Question 18(w) on the application *1241 asks: “Have you ever had or have you now any ... [hjistory of nontraffic eonviction(s) (misdemeanors or felonies).” Manin answered “yes” and wrote “previously reported, no change.” His lawyer confirmed during the administrative proceedings that this disclosure referred only to the 1992 conviction. On April 8, 1997, Manin was again convicted in Barberton Municipal Court of disorderly conduct. On subsequent medical certificate applications, Manin repeatedly failed to disclose either the 1995 or 1997 convictions.
In late 2007, the FAA discovered Manin’s two disorderly conduct convictions. On June 20, 2008, it issued an emergency order immediately revoking his flight certificates and his first class airman medical certificate because of his “multiple falsifications” on airman medical certificate applications in violation of 14 C.F.R. § 67.403. Manin filed an answer to this emergency revocation order, which doubled as an administrative complaint, and in his answer he asserted the affirmative defenses that the complaint was stale under NTSB regulations and that the equitable doctrine of laches applied. He also asserted that he “belie[ved] that the disorderly charge was a minor summary offense, [and] would not have to be reported.” The parties filed cross-motions for summary judgment with the ALJ assigned to hear the case. The ALJ initially denied both motions, finding that material issues of fact remained in dispute.
At a hearing before the ALJ on September 16, 2008, the FAA renewed its motion for summary judgment. The ALJ granted the motion and affirmed the emergency revocation order. Manin appealed to the full Board, which affirmed. In its opinion, the NTSB piggybacked its unelaborated rejection of his laches defense on its longer discussion of why the stale complaint rule is inapplicable, stating that the Board has “long held that the doctrine of laches is relevant to Board cases only in the context of the stale complaint rule.”
Adm’r v. Manin,
NTSB Order No. EA-5430,
Our review of the Board’s opinion and order is governed by the Administrative Procedure Act, which instructs us to uphold the NTSB’s decision unless it is “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law.” 5 U.S.C. § 706(2)(A).
II.
A.
Laches is “an equitable defense that applies where there is (1) lack of diligence by the party against whom the defense is asserted, and (2) prejudice to the party asserting the defense.”
Pro Football, Inc. v. Harjo,
The ALJ found any delay in the FAA’s commencement of its action against Manin to be “inconsequential,” because the FAA “proceeded diligently” once it became aware of Manin’s previous convictions. Manin challenged this decision in his appeal to the Board. The Board held that the stale complaint rule was inapplicable because under Board precedent an allegation of intentional falsification amounts to an allegation of a lack of qualifications.
Manin,
As the FAA now acknowledges, the Board’s statement describing the “long held” limitation on the applicability of the doctrine of laches was simply not accurate. Board case law establishes that the laches defense may be available even when the stale complaint rule is inapplicable. “The Board has indicated on several occasions that, notwithstanding the fact that a complaint may survive dismissal under the stale complaint rule, it might still be subject to attack if an airman could establish actual prejudice in his defense which is attributable to the Administrator’s delay.”
Adm’r v. Wells,
The FAA argues that the Board’s order should be affirmed despite its unexplained departure from precedent because Manin failed to establish a genuine issue of material fact concerning whether the FAA’s alleged delay in revoking his certificates resulted in actual prejudice to his defense. However, we cannot affirm on that basis. It is true that the Board will not give an airman the benefit of a laches defense when he makes only “conclusory allegations ... that delay has adversely affected [his] ability to locate witnesses or produce evidence,” because such allegations are “insufficient to establish that an airman has in fact been prejudiced in defending against a charge.”
Peterson,
When an agency departs from its prior precedent without explanation, as the NTSB did here, its judgment cannot be upheld. “[W]e do not require an agency to grapple with every last one of its precedents, no matter how distinguishable — At the same time, we have never approved an agency’s decision to completely ignore relevant precedent.... [A]n agency’s failure to come to grips with conflicting precedent constitutes ‘an inexcusable departure from the essential requirement of reasoned decision making.’ ”
Jicarilla Apache Nation v. Dep’t of the Interior,
B.
Manin also defended on the merits against the charge of intentional falsification. Intentional falsification of an airman medical certificate, as prohibited by 14 C.F.R. § 67.403(a)(1), has three elements: “(1) a false representation (2) in reference to a material fact (3) made with knowledge of its falsity.”
Singleton v. Babbitt,
The ALJ and the NTSB both rejected Manin’s defense. The Board, citing several cases, declared that it had “previously rejected a respondent’s own interpretation of the requirements of a medical certificate.”
Manin,
After the Board issued its opinion, we decided two cases emphasizing that, under Board law, “a pilot’s understanding of a question is not irrelevant to whether he offered an intentionally false answer under § 67.403(a)(1).”
Singleton,
“Having announced this interpretation of the intent element in Reynolds, the Board was obligated to apply it consistently.” Id. It did not do so in Manin’s case, instead treating Manin’s subjective understanding of the requirements of question 18(w) as irrelevant. The FAA now argues that the decision of the Board was correct because Manin failed to offer any proof in support of his assertion that he misunderstood the question: He did not testify before the ALJ or the NTSB, and the record does not contain any statement whatsoever from Manin himself explaining his contemporaneous understanding of the question. Because Manin did not create a genuine issue of material fact, the FAA concludes, the Board’s decision should be affirmed.
We decline once again to affirm the decision of the Board on an alternate basis.
See Chenery,
*1245 III.
We generally may not uphold agency action on a basis other than that relied upon by the agency. In affirming the revocation of Michael George Manin’s airman certificates, the NTSB departed from its own precedent twice, without explanation. Accordingly, we vacate the Board’s decision and remand for further proceedings consistent with Board precedent and the precedent of this Court.
So Ordered.
Notes
. The FAA invokes the harmless error doctrine, which derives from the APA.
See
5 U.S.C. § 706. We have previously held that ''[w]hen 'there is not the slightest uncertainty as to the outcome of a proceeding' on remand, courts can affirm an agency decision on grounds other than those provided in the agency decision.”
Envirocare of Utah, Inc. v. Nuclear Regulatory Comm’n,
