Direct Answer — The Three Letters at a Glance
A Letter of Correction documents the corrective action you have taken or agreed to take — it is the most favorable of the three and generally closes a matter under 14 CFR §13.11. A Letter of Warning (a “Warning Notice”) is an administrative-action outcome that formally recites the facts and indicates the conduct may have been a violation, but carries no civil penalty and no certificate action. A Letter of Investigation (LOI) is not an outcome at all — it is the formal START of an enforcement investigation, the FAA telling you it is looking into an apparent violation and inviting a response. The first two letters generally close a matter; the third opens one. The Warning Notice and Letter of Correction are named in §13.11; the policy that decides which letter you get lives in FAA guidance — FAA Order 2150.3 (Compliance and Enforcement Program) and FAA Order 8000.373 (Compliance Program). If you receive an LOI, talk to an aviation attorney before responding.
Two are real CFR instruments; the system around them is guidance
The Warning Notice and Letter of Correction are named in the regulation — 14 CFR §13.11. But the process that decides which letter you receive (and when an LOI is sent) lives in FAA guidance — Orders 2150.3 and 8000.373 — not in a single CFR section. Don’t go looking for a “Letter of Investigation” regulation number; it isn’t one.
Three Letters, Three Very Different Messages
Aviation operators tend to lump every official-looking FAA envelope into the same mental bucket labeled “trouble.” That instinct is understandable, but it can lead you to under-react to a serious letter — or panic over a favorable one. These three letters are not points on a single scale of badness; two of them are outcomes that wind a matter down, and one is the opening move of an enforcement investigation. Telling them apart is the first thing to do when one arrives.
This article is specifically about the letters — the actual documents and what each one means. If what you want is the process behind them — how the FAA chooses between fixing a deviation with you and sanctioning it — read the companion guide on FAA compliance action vs enforcement. The two pair together: that one explains the road; this one explains the road signs.
| Letter | What it is | Penalty? | Opens or closes? |
|---|---|---|---|
| Letter of Correction | States corrective action taken/agreed (§13.11); closeout of a compliance or administrative action | None | Closes |
| Letter of Warning (Warning Notice) | Recites facts and indicates conduct may have been a violation (§13.11) | None | Closes |
| Letter of Investigation (LOI) | Formal notice that the FAA has begun investigating an apparent violation; invites a response | Not yet — investigation only | Opens |
One quick terminology note, because it trips people up constantly: a “compliance action” is the FAA’s non-enforcement way of fixing an unintentional deviation, and it can be closed out with a Letter of Correction. So the Letter of Correction is a document; the compliance action is the process that produced it. We unpack that pairing more in the FAQ and in the compliance-action-vs-enforcement guide.
Letter of Correction — The Favorable Closeout
A Letter of Correction is the lightest and most favorable of the three. Under 14 CFR §13.11, the FAA may dispose of certain apparent violations administratively, and a Letter of Correction is the instrument that “states the corrective action the apparent violator has taken or agrees to take.” In plain English: the FAA agrees the matter can be resolved by fixing it, and the letter records the fix.
Receiving one generally signals that the FAA viewed the deviation as an honest, isolated mistake by an operator who was both willing and able to return to compliance — the exact scenario the FAA Compliance Program (Order 8000.373) is designed for. It closes the matter without a civil penalty and without touching your certificate.
What a Letter of Correction typically captures
The corrective action
The specific steps you took or agreed to take to fix the deviation and its root cause.
A completion expectation
Often a timeline or confirmation that the agreed steps are (or will be) done.
The underlying facts
A reference to what was found, so the record is clear about what was corrected.
A closeout
An indication the matter is resolved administratively — not a fine, not a certificate action.
It is a commitment, not a free pass
§13.11 is explicit: if the apparent violator does not complete the agreed corrective action, the FAA may take legal enforcement action. A Letter of Correction is favorable precisely because you committed to a fix — so the burden shifts to proving you did it. Keep dated, immutable evidence that every recited step was actually completed. Whether a particular letter is as favorable as it looks is fact-specific; confirm with aviation counsel.
Because the value of a Letter of Correction lives entirely in your ability to prove the corrective action, the records matter as much as the letter. If the fix involved retraining a pilot, that ties to records like a qualifications and training file; if it involved a maintenance correction, it ties to the way you document corrective action without creating a falsification problem.
Letter of Warning — The Formal Notice, No Penalty
A Letter of Warning — the regulation calls it a Warning Notice — is the other administrative-action instrument named in 14 CFR §13.11. The rule describes it as a notice that “recites available facts and information about the incident or condition and indicates that it may have been a violation.” It is the FAA putting on the record, in writing, that something appeared to be a deviation — without assessing a civil penalty or taking action against a certificate.
Think of it as a formal “we saw this, and we’re noting it.” It is more serious than an informal conversation and is documented by the FAA, but it is still an administrative disposition — the lightest enforcement-side response short of doing nothing. A Warning Notice does not, by itself, carry a fine or affect your authority to operate.
What it does
- Documents the facts of an apparent deviation
- States that the conduct may have been a violation
- Becomes part of the FAA’s administrative record
- Signals the FAA expects it not to recur
What it does not do
- It does not assess a civil penalty (that is §13.16)
- It does not suspend, amend, or revoke a certificate (§13.19)
- It is not an open investigation the way an LOI is
- It is not legal advice from us — confirm specifics with counsel
“Letter of Warning” vs “Letter of Reprimand”
People sometimes search for an FAA “letter of reprimand,” which is an internal personnel term rather than the enforcement instrument here. In the §13.11 enforcement context the document is the Warning Notice, commonly called a Letter of Warning. If a letter you received uses different wording, identify it by what it says it does — recites facts and notes a possible violation (warning), records a corrective action (correction), or announces an investigation (LOI) — and verify with aviation counsel.
Letter of Investigation (LOI) — The Front Door to Enforcement
A Letter of Investigation is categorically different from the other two. It is not an outcome — it is the formal beginning of an enforcement investigation. When FAA inspectors determine that an apparent violation needs more than minimal investigation, FAA guidance (FAA Order 2150.3, the Compliance and Enforcement Program) provides for sending a Letter of Investigation that puts you on notice and gives you an opportunity to respond.
An LOI typically identifies the matter under investigation, references the regulations potentially involved, and invites a written response within a stated period (often around 10 days, though the window varies and any deadline in your letter controls). It is the document that can lead onward to a proposed civil penalty under 14 CFR §13.16 or a certificate action under §13.19 — or, if the facts support it, back down to a warning or correction.
If you receive an LOI, this is the moment to call an aviation attorney
An LOI is a serious legal document, and how you respond can shape the entire matter. A few principles that experienced aviation counsel consistently emphasize — none of which is legal advice for your situation:
- Read the response deadline carefully — but talk to counsel before you write anything.
- You are generally not obligated to respond; anything you submit can be used in the matter.
- Never alter, back-date, or “clean up” a record after receiving an LOI — that can become its own violation.
- Preserve every relevant record exactly as it stands, and organize it so counsel can work from it.
- A statute — the Pilot’s Bill of Rights — may require the FAA to give an airman notice and certain rights once an enforcement investigation begins.
An LOI is also closely tied to the FAA’s voluntary safety programs. If a matter has not yet ripened into an LOI, there may be a window to self-disclose — and whether and how to do that is a strategic, counsel-driven decision. See ASAP vs VDRP vs ASRS — which to file and the operator-focused VDRP voluntary disclosure for Part 135. The protections those programs offer often turn on timing relative to when the FAA already knew about the issue.
An LOI frequently follows a finding from a surveillance audit or a ramp check, and the highest-stakes investigations — the ones involving operational control and intent — are exactly the territory of the FAA crackdown on illegal “grey” charter. The thread through all of them is the same: the records you can produce are the evidence the investigation runs on.
Before any letter arrives, know where your records stand
The fastest way to keep a matter on the Letter-of-Correction side is to be the operator who can prove everything. See your aviation document readiness in minutes.
Related Aviation Compliance Guides
Where the Three Letters Sit on the FAA’s Spectrum
It helps to see the whole field. The FAA can respond to an apparent deviation along a spectrum — from a non-enforcement compliance action, through administrative action, to legal enforcement. These three letters are the visible documents along that spectrum, and two more sanctions sit beyond them.
Closed by a Letter of Correction
A non-enforcement response under the FAA Compliance Program (Order 8000.373) — education, counseling, on-the-spot correction, or remedial training. Frequently memorialized with a Letter of Correction. Not a sanction.
Warning Notice or Letter of Correction (§13.11)
The lightest end of the enforcement framework. A Warning Notice recites facts and notes a possible violation; a Letter of Correction records corrective action. Neither carries a civil penalty or a certificate action.
The start of an enforcement investigation
Not a sanction yet — the formal notice that the FAA is investigating an apparent violation and that the matter could move to legal enforcement. Issued per FAA guidance (Order 2150.3). The moment to engage aviation counsel.
A monetary sanction
A proposed and then assessed monetary penalty under the FAA’s 49 U.S.C. authority, with notice and response rights. A proposed civil penalty is the start of a process, not the end of one.
Suspension, amendment, or revocation
Action against a certificate, with notice, an opportunity to respond, an informal conference option, and appeal rights to the NTSB. Emergency orders take effect immediately.
A statute sits on top: the Pilot’s Bill of Rights
The Pilot’s Bill of Rights (Public Law 112-153, signed August 3, 2012) is a federal statute — not a CFR section or an FAA order. It requires the FAA to give an airman timely written notice of an investigation that could lead to enforcement against an airman certificate, to identify the nature of the investigation, and to advise the airman of certain rights, including the ability to request relevant air traffic data. It governs process once an investigation is under way. A Letter of Investigation is exactly the kind of notice that triggers those considerations.
The Records That Respond to Each Letter
Whatever letter you are holding, your response runs on records. A Letter of Correction has to be backed by proof the corrective action happened. A Warning Notice is best answered by a clean record showing it was a one-off. An LOI is responded to (with counsel) out of the records the FAA will weigh. The operator who can produce a complete, current, immutable, instantly retrievable record set is in a fundamentally stronger position no matter which envelope arrives.
| The letter | What it asks of you | The records that respond |
|---|---|---|
| Letter of Correction | Prove the agreed corrective action was completed | A dated, immutable corrective-action record — completed training, updated procedure, verified re-entry |
| Letter of Warning | Show this was isolated and will not recur | A clean, complete history that frames the deviation as a one-off, plus any process change you made |
| Letter of Investigation | Preserve everything; respond only with counsel | The full, unaltered record set the investigation touches — produced on demand, never edited after the fact |
None of this is about gaming the FAA. It is the opposite: the operator with current, complete, immutable records and a documented corrective-action habit usually is the willing-and-able operator the Compliance Program is built for — and the records simply let them prove it quickly. The operator who cannot find a training record, or whose entries do not match the work, has a harder story to tell even when the underlying mistake was innocent. For the records that come up most across these matters, the international operations document set and your RVSM, altimeter, and transponder inspection records are common examples of currency that an inspector checks first.
FileFlo Is the Records Layer Behind Any FAA Letter
FileFlo is a compliance document intelligence platform — the proof layer for your records. It does not respond to the FAA for you, file a disclosure, give legal advice, run your safety program, or guarantee any outcome. Those belong to you and to qualified counsel. What FileFlo does is keep the document set behind every one of these letters — current, complete, immutable, and instantly retrievable — and help you document corrective action when a Letter of Correction depends on it.
- Classifies and indexes your aircraft, crew, training, and maintenance records so a deviation looks like the one-off it is, not a pattern
- Tracks currency and expirations so fewer deviations happen in the first place — and fewer letters arrive
- Preserves an immutable, version-tracked history — the integrity that keeps a record set defensible and away from any falsification question
- Captures corrective-action documentation (root cause, completed training, verified re-entry) that a Letter of Correction stands or falls on
- Produces an inspector-ready records index on demand, so “produce the records” is a button, not a scramble
FileFlo classifies 600+ document types and manages records across Part 91, Part 135, and Part 145 operators. Pricing: Starter $89/mo, Professional $299/mo. 5-day free trial, no credit card required. FileFlo keeps the documents that prove compliance audit-ready — it is not an SMS, a dispatch/flight-operations system, an attorney, or a guarantee of any FAA outcome.
Frequently Asked Questions
What is the difference between an FAA Letter of Correction, a Letter of Warning, and a Letter of Investigation?
They are three different documents that mean three very different things. A Letter of Correction documents the corrective action you have taken or agreed to take — it is the closeout of a compliance action or the lightest end of administrative action under 14 CFR §13.11. A Letter of Warning (also called a Warning Notice) is an administrative-action outcome that recites the facts and indicates the conduct may have been a violation, but carries no civil penalty and no certificate action. A Letter of Investigation (LOI) is the opposite of an outcome — it is the formal START of an enforcement investigation, the FAA telling you it is looking into an apparent violation and giving you a chance to respond. The first two close a matter; the third opens one. If you receive an LOI, contact an aviation attorney before you respond.
What does a Letter of Correction mean — is it an enforcement action?
A Letter of Correction is the FAA's way of documenting that a deviation has been corrected. Under 14 CFR §13.11, it 'states the corrective action the apparent violator has taken or agrees to take.' It is the lightest, most favorable letter you can receive — it generally means the FAA viewed the matter as an unintentional deviation by an operator who was willing and able to fix it, and it closes the matter administratively rather than through a civil penalty or certificate action. The important catch, written into the rule itself: if you do not complete the agreed corrective action, the FAA may take legal enforcement action. So a Letter of Correction is not a free pass — it is a commitment. Keep the records that prove you completed every step. Whether any specific letter is favorable for you is fact-specific; consult aviation counsel.
What is an FAA Letter of Investigation (LOI) and how should I respond?
A Letter of Investigation is the formal notice the FAA sends when it has begun investigating an apparent violation that could lead to enforcement. It typically identifies the matter under investigation, references the regulations potentially involved, and invites you to submit a written response — often within a stated window (commonly around 10 days, though it varies). An LOI is a serious document: it is the front door to the legal-enforcement track. You are generally not required to respond, and anything you say can be used in the matter, which is exactly why the near-universal advice is to consult a qualified aviation attorney BEFORE responding to an LOI. Do not 'clean up' or alter any records after receiving one. Your job in the meantime is to preserve and organize the records the FAA will weigh — FileFlo helps with that, but it does not represent you or give legal advice.
Does a Letter of Warning or Letter of Correction go on my FAA record?
Both a Warning Notice (Letter of Warning) and a Letter of Correction are administrative actions that the FAA documents — they are recorded in the FAA's enforcement information system rather than simply disappearing. They are not civil penalties and not certificate suspensions or revocations, so they do not by themselves carry a fine or affect your certificate. How long such an entry is retained, and how it is treated in any later matter, are fact-specific questions governed by FAA policy and records practices, and they can change over time. This is precisely the kind of detail to confirm with aviation counsel for your situation rather than relying on a general article. The practical takeaway is the same regardless: treat any FAA letter seriously, complete every committed corrective step, and keep the documentation that proves you did.
Which FAA letter is the most serious?
Ranked from most favorable to most serious among these three: a Letter of Correction is the lightest — it documents a fix and closes the matter. A Letter of Warning (Warning Notice) is next — it formally notes that conduct may have been a violation, with no penalty. A Letter of Investigation is the most serious of the three because it is not an outcome at all — it signals an open enforcement investigation that could lead to a civil penalty (14 CFR §13.16) or a certificate action (§13.19). Beyond these letters sit the actual enforcement sanctions: a proposed civil penalty and an order of suspension, amendment, or revocation. An LOI is the moment to call an aviation attorney.
Are these FAA letters defined in the regulations (CFR) or in FAA guidance?
It is a mix, and getting it straight matters. The Warning Notice and Letter of Correction are named in the regulation itself — 14 CFR §13.11, 'Administrative disposition of certain violations.' The broader machinery — how field personnel decide between a compliance action, administrative action, and legal enforcement, when a Letter of Investigation is issued, and how cases are documented — lives in FAA GUIDANCE, principally FAA Order 2150.3 (the Compliance and Enforcement Program) and FAA Order 8000.373 (the Compliance Program). So the letters you receive are real instruments under §13.11, but the policy that decides which one you get is found in FAA orders, not in a single CFR section. Always verify against the current regulation and order, and consult counsel for any live matter.
How is a compliance action different from these letters?
A compliance action is a non-enforcement response under the FAA Compliance Program (FAA Order 8000.373) — education, on-the-spot correction, counseling, or remedial training to fix an unintentional, non-reckless deviation. It can be CLOSED OUT with a Letter of Correction, which is why the two are often confused. The distinction: 'compliance action' describes the PROCESS the FAA chose (fix it, don't sanction it), while a Letter of Correction is one of the DOCUMENTS that can memorialize it. A Letter of Warning and a Letter of Investigation, by contrast, belong to the enforcement framework in 14 CFR Part 13 — the warning at its lightest end and the LOI at the start of an investigation. For the process-level picture, see our companion guide on FAA compliance action versus enforcement; this article is about the specific letters.
Can a Letter of Correction turn into an enforcement action later?
Yes — and the regulation says so directly. 14 CFR §13.11 provides that if the apparent violator does not complete the agreed corrective action, the FAA may pursue legal enforcement action. In practice, the corrective steps recited in a Letter of Correction are commitments: a documented training syllabus completed, a procedure updated, a record corrected the right way. If those commitments are not met — or if new facts show the conduct was actually intentional, reckless, or part of a pattern — a matter that started favorably can move toward a civil penalty or certificate action. This is the single best reason to keep immutable, dated proof that every committed step was actually done. It is also why falsifying or back-dating a record to look compliant is so dangerous: it can become its own basis for enforcement. Consult aviation counsel on any specific commitment.
Whichever letter arrives, be the operator who can prove it.
FileFlo keeps your aviation records current, complete, immutable, and instantly retrievable, and documents the corrective action a Letter of Correction depends on. It does not respond to the FAA for you, give legal advice, or guarantee an outcome — it organizes and proves your records. Starter plan $89/mo. Professional $299/mo. 5-day free trial — no credit card required.
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Written by Chad Griffith, Founder, FileFlo — compliance document intelligence. Reviewed June 15, 2026. This article is general compliance document information, not legal advice. The Warning Notice and Letter of Correction are named in 14 CFR §13.11; the policy that decides which letter you receive (and when a Letter of Investigation is issued) is FAA guidance — FAA Order 2150.3 (Compliance and Enforcement Program) and FAA Order 8000.373 (Compliance Program). The Pilot’s Bill of Rights (Public Law 112-153) is a statute. The meaning and consequences of any FAA letter are fact-specific — if you receive a Letter of Investigation, or any FAA inquiry or enforcement action, consult a qualified aviation attorney before responding, do not alter any record, and verify every regulation and order reference against the current source.