dissenting:

I agree with that part of Judge Reinhardt’s opinion which holds that the failure of the NTSB to act within 60 days does not divest it of jurisdiction, but I disagree that the Board’s failure to act in timely fashion has anything to do with the certificate holder’s obligation to file a timely emergency appeal within the ten-day period provided for emergency appeals in 49 C.F.R. § 821 .-55(a). Because I believe the ten-day limit is a clear requirement, I would affirm.

49 U.S.CApp. § 1429(a), which empowers the FAA to suspend or revoke an airman mechanic’s certificate, contemplates both emergency and non-emergency revocations. The emergency rule provides:

49 C.F.R. § 821.55 (a). Consistent with this regulation, the notice — captioned “APPEAL” — that was attached to the FAA’s revocation order stated:

Grant argues that he misinterpreted § 821.55(a) to mean that he had a choice between appealing within 10 days on the emergency track or appealing within the 20 days allowed for non-emergency appeals, 1 thereby foregoing the benefits of expedited emergency procedures. That scheme might be a good idea, but it is not the scheme embodied in the regulations, which say nothing about a choice. The emergency procedures and the non-emergency procedures are two different tracks. Once a case is on the emergency track, the rules in subpart I control, 2 and the ten-day limit applies. 3

Even if the regulation were not clear on its face, the Board’s interpretation is rea *1488 sonable and is therefore entitled to deference. Ud all v. Tallman, 380 U.S. 1, 4 , 85 S.Ct. 792, 795 , 13 L.Ed.2d 616 (1965) (Agency’s “interpretation may not be the only one permitted by the language of the [rules], but it is quite clearly a reasonable interpretation; courts must therefore respect it.”). In addition, the NTSB has previously rejected the interpretation that Grant urges, see Administrator v. Myers, N.T.S.B. Order No. EA-2405 (1986), and its current interpretation should be accorded “great weight” for that reason as well. NLRB v. Bell Aerospace Co., 416 U.S. 267, 275 , 94 S.Ct. 1757, 1762 , 40 L.Ed.2d 134 (1974).

Grant further argues that he was deprived of due process because the notice was incomplete and ambiguous, and failed to advise him that he would lose all right to contest the allegations unless he appealed within ten days. He suggests that the fact the notice says a person “may” appeal, instead of “must” appeal, within ten days means the ten-day limit may be adhered to or ignored at the certificate holder’s discretion. In support, he contrasts the language of 49 C.F.R. § 821.30 (a), which uses “shall” to describe the twenty-day period for non-emergency appeals.

The word “may” in § 821.55(a) cannot reasonably be interpreted to refer to the time limit or to render the limit permissive; otherwise, the time limit itself makes no sense. Either there is a time limit, or there isn’t. Rather, “may” is simply a way of saying the certificate holder can appeal if he wants to. See Goodman v. City Prod. Corp., 425 F.2d 702, 703 (6th Cir.1970) (“The permissive verb ‘may’ [in Civil Rights Act provision stating that ‘a civil action may ... be brought’ within thirty days] refers to the option of the aggrieved party to bring a lawsuit, not to a discretion in the Court to receive the case following the expiration of 30 days.”). That the non-emergency rule provides that anyone who chooses to appeal “shall” appeal within 20 days is immaterial, because the construct of § 821.30(a) is different from that of § 821.55(a). 4 Nor is the notice deficient for failure to spell out the consequences of not filing an appeal within the ten-day period. “All citizens are presumptively charged with knowledge of the law,” Atkins v. Parker, 472 U.S. 115, 130 , 105 S.Ct. 2520, 2529 , 86 L.Ed.2d 81 (1985), including in this case the provision that an extension of time to file any document, including the appeal, could be obtained only for good cause.

Grant does not dispute that the NTSB has the power of plenary review, but argues that it has limited its own power by permitting an AU to accept a late filing. There is no authority for such a constraint. The regulations provide that both an AU and the Board can make findings of good cause. 49 C.F.R. § 821.11 . The Board’s finding that Grant lacked good cause for missing the deadline should be upheld because it is subject to a substantial evidence standard, 49 U.S.C.App. § 1486(a), 5 U.S.C. §■ 706(2)(E), and there was substantial evidence to support it. The order had first been received by a Grant employee weeks before it was personally served on Grant; after he was personally served, Grant waited eight days to contact his lawyer; the FAA order contained an explicit statement on the filing of an appeal; and Grant himself testified that he read the FAA emergency order several times and understood it.

Thus Grant's appeal was untimely, and the Board’s finding that good cause for an extension was lacking is well supported. Unless the Board’s own default in rendering its decision within the 60 days prescribed by 49 U.S.C.App. § 1429(a) spills over to the timeliness of Grant’s appeal under 49 C.F.R. § 821.55 (a), the decision must be affirmed.

There is no precedent for penalizing an agency for its failure to comply with a time limit for decision by requiring it to hear an *1489 untimely appeal. Judge Reinhardt justifies this result because, when the Board “acts in an untimely fashion, it would be unduly harsh to permit it to forfeit a petitioner’s right to an appeal for acting similarly.” Although this may appear to be a fair tit for tat under the circumstances, in effect it amounts to an equitable estoppel against the government for which no authority exists in the absence of affirmative misconduct. See, e.g., Bolt v. United States, 944 F.2d 603, 609 (9th Cir.1991) (“[F]or the government to be estopped there must be affirmative misconduct (not mere negligence) and a serious injustice outweighing the damage to the public interest of estop-ping the government.”); Santiago v. INS, 526 F.2d 488, 491 (9th Cir.1975) (en banc) (“[T]he rule of estoppel ... can only be invoked if the governmental conduct complained of amounts to ‘affirmative misconduct.’ ”) (quoting INS v. Hibi, 414 U.S. 5, 8 , 94 S.Ct. 19, 21 , 38 L.Ed.2d 7 (1973) (per curiam)), cert. denied, 425 U.S. 971 , 96 S.Ct. 2167 , 48 L.Ed.2d 794 (1976); see also Heckler v. Community Health Serv., 467 U.S. 51, 60 , 104 S.Ct. 2218, 2224 , 81 L.Ed.2d 42 (1984) (“[I]t is well settled that the Government may not be estopped on the same terms as any other litigant.”); cf. Office of Personnel Management v. Richmond, 496 U.S. 414, 421-26, 432-34 , 110 S.Ct. 2465, 2470-72, 2476 , 110 L.Ed.2d 387 (1990) (holding that estoppel cannot be invoked in monetary claims against the government; declining to pass on desirability of “an across-the-board no-estoppel rule”).

Judge Reinhardt’s opinion further argues that as a practical matter what happened is exactly the same as if the certificate holder had waived the emergency procedures and sought review under the ordinary non-emergency procedures, thereby “enlarging] beyond the statutory period the time during which the emergency revocation of a license may remain in effect.” Perhaps, but there is no provision in the regulations for any such election; the certificate holder may request an extension if he wants more time to prepare his defense, but there is no provision for waiving the emergency time limits. Nor does it follow, as Judge Reinhardt’s opinion holds, that “[bjecause the actions of the board denied Grant the benefit of the emergency rules, it would be unfair to require him to comply with the shortened filing requirements.” Neither Grant nor any other certificate holder aggrieved by the Board’s failure to render a decision within 60 days is without remedy. Under the Administrative Procedure Act, the certificate holder may petition a district court to “compel agency action unlawfully withheld or unreasonably delayed.” 5 U.S.C. § 706 (1).

I therefore respectfully dissent.

. The non-emergency rule provides:

49 C.F.R. § 821.30 (a).

. Subpart I of 49 C.F.R. ch. VIII, pt. 821 ("Rules of Practice in Air Safety Proceedings”) sets out the rules applicable to emergency proceedings. Within subpart I, § 821.54(a) provides:

.This is not to say the certificate holder may not, within that ten-day limit, apply for an extension of time. See 49 C.F.R. § 821.11 .

. Section 821.30(a) is broken into two sentences, the first of which states that a certificate holder “may” appeal from a revocation order. See supra n. 1. The word "may” in this section is used identically to the same word in § 821.-55(a) and makes clear that "may” in § 821.55(a) simply refers to the certificate holder’s option to pursue an appeal, not his option to choose the applicable time limit.