49 CFR 1503.301 - Warning notices and letters of correction.
(a) If TSA determines that a violation or an alleged violation of a TSA requirement does not require the assessment of a civil penalty, an appropriate official of the TSA may take administrative action in disposition of the case.
(b) An administrative action under this section does not constitute a formal adjudication of the matter, and may be taken by issuing the alleged violator -
(1) A “Warning Notice” that recites available facts and information about the incident or condition and indicates that it may have been a violation; or
(2) A “Letter of Correction” that confirms the TSA decision in the matter and states the necessary corrective action the alleged violator has taken or agrees to take. If the agreed corrective action is not fully completed, legal enforcement action may be taken.
(c) The issuance of a Warning Notice or Letter of Correction is not subject to appeal under this part.
(d) In the case of a public transportation agency that is determined to be in violation of a TSA requirement, an appropriate TSA official will seek correction of the violation through a written “Notice of Noncompliance” to the public transportation agency giving the public transportation agency reasonable opportunity to correct the violation or propose an alternative means of compliance acceptable to TSA.
(e) TSA will not take legal enforcement action against a public transportation agency under subpart E unless it has provided the Notice of Noncompliance described in paragraph (d) of this section and the public transportation agency fails to correct the violation or propose an alternative means of compliance acceptable to TSA within the timeframe provided in the notice.
(f) TSA will not initiate civil enforcement action for violations of administrative and procedural requirements pertaining to the application for, and the expenditure of, funds awarded pursuant to transportation security grant programs under Public Law 110-53.