Direct Answer — What §91.207 Requires for the ELT
14 CFR §91.207 imposes two recurring ELT obligations that run on different clocks. Under §91.207(c), the battery must be replaced (or recharged, if rechargeable) when the transmitter has been in use for more than 1 cumulative hour, or when 50 percent of its useful life (or, for rechargeable batteries, 50 percent of its useful life of charge) has expired — and the new expiration date must be legibly marked on the outside of the transmitter and entered in the aircraft maintenance record. Under §91.207(d), each required ELT must be inspected within 12 calendar months after the last inspection for (1) proper installation, (2) battery corrosion, (3) operation of the controls and crash sensor, and (4) the presence of a sufficient signal radiated from its antenna.
The two are independent: the battery rule is use-driven and life-driven; the inspection is calendar-driven. An aircraft can have a current 12-month inspection and still be overdue on the battery. Section §91.207(a) requires an approved automatic type ELT in operable condition for most operations — it does not, in its own text, prescribe 121.5 vs 406 MHz. Sections (e) and (f) provide ferry allowances and a list of excepted aircraft, and (f)(10) permits temporary removal for up to 90 days with a maintenance-record entry and an ELT not installed placard in view of the pilot.
Sources: 14 CFR §91.207, 14 CFR §43.9, 14 CFR §91.417 — eCFR.
The ELT is a small piece of equipment with an outsized compliance footprint, because it carries two separate recurring requirements that share a battery but not a clock. Get the wrong mental model — "I did the ELT at the annual, so it is good for a year" — and an aircraft can be flying with a current inspection but a lapsed battery, or a current battery in a unit whose 12-month inspection expired. This article walks the §91.207 text paragraph by paragraph, then shows where the proof lives: the marked expiration date the rule mandates, the maintenance record entry, and how ELT currency rolls up into the Part 91 aircraft records an owner keeps.
Why it matters for documentation: the inspection and the battery work are the mechanic's job, but the proof that they happened — the marked unit, the §91.207(c) maintenance-record entry, and the 12-month inspection entry recorded in practice under 14 CFR §43.9 — is what a ramp inspector or auditor reviews. A serviceable ELT with a missing record is a finding. FAA civil penalties for recordkeeping and airworthiness violations under 49 U.S.C. § 46301 reach $75,000 per violation (with a lower maximum of $1,875 per violation for an individual or small-business concern in certain cases) under 14 CFR §13.301 for violations occurring on or after December 30, 2024.
The Battery Rule — §91.207(c), Use-Driven and Life-Driven
This is the paragraph that produces the expiration date stamped on the side of the unit. Read it carefully, because the trigger is "whichever comes first," and the record obligation is built into the rule itself.
14 CFR §91.207(c) — the replacement trigger and the record
Batteries used in the ELT required by paragraphs (a) and (b) of §91.207 must be replaced (or recharged, if the batteries are rechargeable):
- (1)When the transmitter has been in use for more than 1 cumulative hour; or
- (2)When 50 percent of their useful life (or, for rechargeable batteries, 50 percent of their useful life of charge) has expired, as established by the transmitter manufacturer under its approval.
And the rule does not stop at the trigger. It continues: the new expiration date for replacing (or recharging) the battery must be legibly marked on the outside of the transmitter and entered in the aircraft maintenance record. That dual obligation — mark the unit and make the record entry — is the part operators most often half-complete.
The 50% date is not the printed shelf life
The expiration date marked under §91.207(c) reflects the 50 percent of useful life point that the rule requires, not the battery's full manufacturer-printed shelf-life date. That is why an ELT battery is replaced years before the cell itself would die — the regulation deliberately builds in margin so the unit is reliable when it is needed.
"In use" means cumulative transmitting time
The 1-hour trigger is cumulative transmitting use, not flight time. A single inadvertent activation that ran for an extended period, or repeated test transmissions, can accumulate toward that hour. If an ELT is known to have transmitted — for example after a hard landing or an accidental activation — the battery clock under (1) is in play regardless of the marked 50% date.
Because the marked date and the maintenance-record entry are both mandated by the rule, the ELT battery is one of the cleaner items to track in a document system: the unit carries a date, the record carries a date, and they should agree. Where they diverge — a unit marked with one date and a record showing another, or a marked unit with no corresponding entry — you have a documentation defect to resolve before an inspector finds it. This is the same record discipline that governs weight and balance records and altimeter and transponder test records: the equipment and the paperwork have to tell the same story.
The 12-Calendar-Month Inspection — §91.207(d), Four Items
Section 91.207(d) requires that each ELT required by paragraph (a) be inspected within 12 calendar months after the last inspection for the four items below. That is the complete statutory scope — installation, corrosion, controls and crash sensor, and radiated signal.
Proper installation
The transmitter must be inspected for proper installation. This ties back to §91.207(b), which requires the ELT to be attached to the airplane in such a manner that the probability of damage to the transmitter in the event of crash impact is minimized. A unit that has worked loose from its mounting, or been reinstalled incorrectly after another task, fails this item.
Battery corrosion
The transmitter must be inspected for battery corrosion. Corrosion at the battery terminals or in the battery compartment can disable the unit regardless of the marked expiration date, which is why the 12-month inspection checks physical battery condition independently of the use-driven and life-driven replacement triggers in §91.207(c).
Operation of the controls and crash sensor
The transmitter must be inspected for operation of the controls and crash sensor (the G-switch). The crash sensor is what activates an automatic-type ELT on impact; the controls are the cockpit and unit switches. This is a functional check, not merely a visual one.
Sufficient signal radiated from its antenna
The transmitter must be inspected for the presence of a sufficient signal radiated from its antenna. A serviceable transmitter with a disconnected, damaged, or improperly routed antenna will not produce a usable distress signal — so the inspection confirms the signal actually radiates, typically using procedures coordinated to avoid transmitting a false alert.
Calendar-month, not flight-hour — and not the same clock as the annual
"Within 12 calendar months" means the inspection is due by the end of the twelfth calendar month after the last one — a familiar pattern shared by the annual inspection and the 24-calendar-month altimeter/transponder tests. But the §91.207(d) ELT inspection is its own item with its own due date. It is commonly accomplished during the annual and signed off together, yet if it was last done as a standalone task in a different month, that earlier month controls. Treating the ELT 12-month as if it always rides the annual is a frequent way aircraft slip out of compliance.
Testing the radiated signal without triggering a false alert
Item (d)(4) confirms a sufficient signal radiates from the antenna. Because live ELT transmissions are detected by the search-and-rescue system, signal checks are coordinated to avoid false distress alerts — typically conducted within a short window and monitored on the receiving frequency, consistent with FAA guidance. The compliance point for your records is simply that the (d)(4) check was performed and documented; the procedural details belong to the technician performing it.
Ferry Flights, Excepted Aircraft, and the 90-Day Removal Placard
Section 91.207 also tells you when you may operate without a fully installed, required ELT. Two paragraphs do the work, and they are easy to mix up.
§91.207(e) — Ferry flights for installation or repair
Paragraph (e) permits operating an airplane to ferry a newly acquired airplane from the place where possession of it was taken to a place where the ELT is to be installed, and to ferry an airplane with an inoperative ELT from a place where repairs or replacements cannot be made to a place where they can. The catch: no person other than required crewmembers may be carried aboard an airplane being ferried under paragraph (e). It is a positioning allowance for getting the equipment installed or fixed, not a way to keep flying passengers.
§91.207(f) — Excepted aircraft and operations
Paragraph (f) lists categories to which the paragraph (a) requirement does not apply — including (paraphrasing) turbojet-powered aircraft; scheduled flights by scheduled air carriers; training conducted entirely within a 50-nautical-mile radius of the departure airport; flight operations incident to design and testing; new aircraft incident to manufacture, preparation, and delivery; aerial application of agricultural chemicals; aircraft certificated for research and development; aircraft used for showing compliance with regulations, crew training, exhibition, air racing, or market surveys; and aircraft equipped to carry not more than one person. Confirm the current eCFR text and your specific category before relying on any exception.
§91.207(f)(10) — Temporary removal: 90 days, an entry, and a placard
Paragraph (a) also does not apply during any period for which the ELT has been temporarily removed for inspection, repair, modification, or replacement — but only if both conditions are met. First, the aircraft records must contain an entry that includes the date of initial removal, the make, model, serial number, and reason for removing the transmitter, and a placard located in view of the pilot to show ELT not installed. Second, the aircraft may not be operated more than 90 days after the ELT was initially removed. The 90 days runs from initial removal, not from when you noticed it was gone.
The §91.207(f)(10) removal record — what the entry must capture
[Date of initial removal] June 11, 2026
[Make / Model] ACME ELT, Model 406-X
[Serial number] SN 00-12345
[Reason for removal] Removed for battery replacement / bench repair
[Placard] "ELT not installed" placard posted in view of the pilot
[Operating limit] May not operate more than 90 days after June 11, 2026 (i.e., not after Sept 9, 2026)
Illustrative only — confirm the current §91.207(f)(10) text and compute the 90-day limit for your actual removal date. The placard wording and the record content are both required; one without the other does not satisfy the exception.
See whether your ELT records would survive a ramp check
FileFlo classifies aviation maintenance documents against the governing CFR — including the §91.207(c) battery expiration entry, the §91.207(d) 12-month inspection record, and the way ELT currency rolls into the §91.417(a)(2) inspection status — and assembles an inspector-format binder on demand. See the full Aviation compliance coverage.
The Records — Where ELT Compliance Is Proven
ELT compliance lives across a few documents, and the §91.207 text tells you exactly what the load-bearing one is. The battery rule itself mandates a maintenance-record entry; the 12-month inspection is, in practice, recorded as a maintenance entry under 14 CFR §43.9; and the currency of the inspection rolls up into the records an owner keeps under §91.417. Here is how the pieces fit.
1. The marked unit + the §91.207(c) maintenance-record entry
This is the only ELT record the §91.207 text expressly mandates by name: the new battery expiration date must be legibly marked on the outside of the transmitter and entered in the aircraft maintenance record. The marked date and the record entry should match. A marked unit with no entry, or an entry with no marked unit, is an incomplete §91.207(c) record.
2. The §91.207(d) 12-month inspection entry (recorded under §43.9 in practice)
The 12-calendar-month inspection is maintenance, and the completion is documented as a maintenance record entry — describing the work performed, the date, and the signature and certificate number of the person who performed or approved it, consistent with §43.9. Note that §43.9 is the general maintenance-entry rule and expressly excludes the inspections performed under part 91 (annual / 100-hour) that are handled under §43.11 — but the §91.207(d) ELT check is a maintenance task documented in the maintenance record, not an Appendix D inspection sign-off.
3. The §91.417 records — where ELT currency rolls up
Under §91.417(a)(1), records of maintenance and of required inspections are retained until the work is repeated or superseded, or for 1 year after it is performed. The current inspection status of the aircraft — which includes the ELT 12-month inspection — is part of the §91.417(a)(2) records the owner keeps and transfers with the aircraft at sale. See our aviation records retention schedule for how long each record class is kept.
4. The 406 MHz beacon registration (NOAA program, not a §91.207 cite)
If the aircraft carries a 406 MHz ELT, the beacon is registered through NOAA's U.S. 406 MHz beacon registration database for the Cospas-Sarsat program, linking the beacon hex ID to the aircraft and emergency contacts. We frame this cautiously: it is a program and FAA-guidance practice, not a recordkeeping clause written into §91.207. Keep the registration current and the confirmation with the aircraft records — but do not cite a §91.207 paragraph for the registration itself.
A note on 121.5 MHz vs 406 MHz — verify, don't assume
The §91.207(a) text requires an approved ELT; it does not, by its own words, force 406 MHz. The international satellite system ceased processing 121.5/243 MHz alerts in 2009, so a 121.5 MHz ELT is no longer satellite-detected, but the FAA has not issued a blanket §91.207 replacement mandate for all general-aviation aircraft. Whether your specific operation effectively requires 406 MHz can turn on operations specifications, airspace, route, or insurer and program requirements — so confirm rather than assume the CFR alone forces the upgrade.
Related Part 91 / Part 135 equipment & records resources
- Part 91 aircraft records — §91.417 maintenance + inspection record retention
- 14 CFR §91.409 — Annual / 100-hour inspection (often paired with the ELT 12-month)
- 14 CFR §43.9 — Maintenance record entry (how the ELT work is documented)
- Altimeter / transponder inspection records — the parallel 24-month equipment cycle
- Part 135 emergency & survival equipment records — the broader survival-gear picture
- Aircraft ARROW documents — the documents required aboard the aircraft
- Aviation records retention schedule — how long to keep each record class
- What records must a Part 135 operator keep — the on-demand records set
Where the ELT Is the Mechanic's Job — and the Proof Is Yours
The battery replacement and the 12-month inspection are obligations on the person performing the work. FileFlo does not perform inspections, replace batteries, hold a certificate, or replace an A&P or repair station. What it does is govern the documentary aftermath — the marked-date entry the rule mandates, the inspection record, and the way ELT currency surfaces in the records an owner and a Part 135 operator must keep.
Battery-due and inspection-due tracking on two clocks
FileFlo reads the marked §91.207(c) battery expiration date from the document, tracks the 12-calendar-month §91.207(d) inspection separately, and surfaces both so the use-and-life-driven battery clock and the calendar-driven inspection clock do not get collapsed into one. It does not perform the work; it tracks the dates and flags the one that is closest to lapsing.
Entry completeness — does the record match the unit?
FileFlo classifies the ELT-related entries and surfaces whether the §91.207(c) maintenance-record entry exists and agrees with the marked unit, and whether the §91.207(d) inspection entry captures the work, date, and signature expected of a §43.9 entry — so a missing or mismatched record is caught before, not during, an FAA review.
Roll-up into the inspection status the owner keeps
The ELT 12-month inspection is part of the current inspection status under §91.417(a)(2), and for on-demand operators it sits inside the larger records set. FileFlo keeps it indexed alongside the rest so the ELT is not the one item missing when you assemble records for a Part 135 surveillance audit or a Part 145 audit binder.
Frequently Asked Questions
How often must an ELT battery be replaced under 14 CFR §91.207?
Under 14 CFR §91.207(c), the batteries used in the ELT required by paragraphs (a) and (b) must be replaced (or recharged, if the batteries are rechargeable) when the transmitter has been in use for more than 1 cumulative hour, or when 50 percent of their useful life (or, for rechargeable batteries, 50 percent of their useful life of charge) has expired. Critically, the rule continues: the new expiration date for replacing (or recharging) the battery must be legibly marked on the outside of the transmitter and entered in the aircraft maintenance record. So the trigger is whichever comes first — one cumulative hour of actual transmitting use, or the 50 percent point of the battery useful life established by the manufacturer. The expiration date you see stamped on the unit is the 50 percent date, not the manufacturer printed shelf-life date.
What does the 12-month ELT inspection under §91.207(d) actually check?
Section 91.207(d) requires that each emergency locator transmitter required by paragraph (a) be inspected within 12 calendar months after the last inspection for four things: (1) proper installation; (2) battery corrosion; (3) operation of the controls and crash sensor; and (4) the presence of a sufficient signal radiated from its antenna. That is the complete statutory scope of the 12-calendar-month inspection — installation, corrosion, controls and crash sensor function, and radiated signal. It is a separate recurring requirement from the battery replacement rule in §91.207(c): the inspection is calendar-driven (every 12 calendar months), while the battery replacement is use-driven and life-driven (1 cumulative hour or 50 percent of useful life). An aircraft can have a current 12-month inspection and still be out of compliance on the battery, or vice versa.
Does §91.207 require a 406 MHz ELT instead of 121.5 MHz?
The text of 14 CFR §91.207(a) does not itself prescribe a transmitting frequency — it requires an approved automatic type emergency locator transmitter that is in operable condition (with a personal type permitted for certain non-commercial operations under (a)(2)). The frequency question lives in the equipment approval standards and FAA guidance, not in the words of §91.207(a). In practice, the international Cospas-Sarsat satellite system stopped processing 121.5/243 MHz distress alerts in 2009, so a 121.5 MHz ELT is no longer satellite-detected and is generally heard only by overflying aircraft and ground stations on that frequency. A 406 MHz ELT (typically approved under TSO-C126) is satellite-detected and carries coded identification. The FAA has not issued a blanket §91.207 mandate to replace 121.5 MHz ELTs in all general-aviation aircraft, so verify your specific operation, any operations specifications, and your insurer or program requirements rather than assuming the CFR forces 406 MHz.
Where is the ELT battery and inspection compliance documented?
Two records carry the proof. First, §91.207(c) requires the new battery expiration date to be both legibly marked on the outside of the transmitter and entered in the aircraft maintenance record — so the maintenance record entry is mandatory, not optional. Second, the 12-calendar-month inspection under §91.207(d) is a maintenance task, and in practice its completion is recorded as a maintenance record entry under 14 CFR §43.9 (the general maintenance-entry rule), describing the work, the date, the aircraft time in service as applicable, and the signature and certificate number of the person who performed or approved it. The currency of that inspection then feeds the current inspection status the owner must keep under §91.417(a)(2)(iv). FileFlo classifies those entries, reads the marked expiration date, and tracks both the battery-due and the 12-month-inspection-due dates against the rule.
Can an aircraft fly with the ELT removed?
Yes, within a narrow, documented window. 14 CFR §91.207(f)(10) provides that paragraph (a) does not apply to an aircraft during any period for which the transmitter has been temporarily removed for inspection, repair, modification, or replacement, subject to conditions: the aircraft records must contain an entry that includes the date of initial removal, the make, model, serial number, and reason for removing the transmitter, and a placard located in view of the pilot to show ELT not installed; and the aircraft may not be operated more than 90 days after the ELT was initially removed from the aircraft. Separately, §91.207(e) permits ferrying a newly acquired airplane from the place possession was taken to a place where the ELT is to be installed, and ferrying an airplane with an inoperative ELT to a place where it can be repaired — but no person other than required crewmembers may be carried during such ferrying.
Which aircraft are excepted from the ELT requirement under §91.207(f)?
Section 91.207(f) lists the categories to which paragraph (a) does not apply. They include (paraphrasing the rule) turbojet-powered aircraft; aircraft while engaged in scheduled flights by scheduled air carriers; aircraft while engaged in training operations conducted entirely within a 50-nautical-mile radius of the airport from which the training flight began; aircraft while engaged in flight operations incident to design and testing; new aircraft while engaged in flight operations incident to their manufacture, preparation, and delivery; aircraft while engaged in flight operations incident to the aerial application of chemicals and other substances for agricultural purposes; aircraft certificated by the Administrator for research and development purposes; aircraft while used for showing compliance with regulations, crew training, exhibition, air racing, or market surveys; aircraft equipped to carry not more than one person; and aircraft during any period for which the ELT has been temporarily removed under the (f)(10) conditions above. Confirm the current eCFR text and your specific category before relying on an exception.
Is the ELT 12-month inspection the same as the annual inspection?
No, though the two are commonly performed together. The annual or 100-hour inspection scope is set by Appendix D to Part 43, and §91.207(d) is its own separate 12-calendar-month requirement directed specifically at the ELT. An A&P or repair station will often accomplish the §91.207(d) ELT inspection during the annual and document both, but they are distinct compliance obligations with their own due dates. If the annual is performed in March and the ELT 12-month inspection happened the prior November as a standalone task, the ELT inspection is due the following November, not the following March. Tracking them as one item is a common way aircraft drift out of ELT compliance between annuals.
Who registers a 406 MHz ELT, and is that a CFR requirement?
Registration of a 406 MHz ELT beacon is handled through NOAA, which operates the U.S. 406 MHz beacon registration database for the Cospas-Sarsat program. That registration links the beacon hex ID to the aircraft and emergency contact information so search and rescue can respond quickly. It is a program and FAA-guidance practice rather than a recordkeeping obligation written into the text of §91.207 itself, so we describe it cautiously: keep the beacon registration current and the confirmation with the aircraft records, but do not cite a §91.207 paragraph for the registration act. FileFlo can index and date-track the registration confirmation alongside the §91.207(c) and (d) records so the whole ELT picture sits in one place.
Related Aviation Compliance Reading
Part 91 Aircraft Records Requirements
§91.417 maintenance + inspection record retention
Part 135 Emergency & Survival Equipment Records
The broader survival-equipment recordkeeping picture
RVSM / Altimeter / Transponder Inspection Records
The parallel 24-month equipment test cycle
Annual / 100-Hour Inspection Scope (Appendix D)
The inspection the ELT 12-month is often paired with
Aircraft ARROW Documents
The documents required aboard the aircraft
What Records Must a Part 135 Operator Keep
Where ELT currency fits in the on-demand records set
Keep both ELT clocks visible before either one lapses
FileFlo is a compliance document intelligence platform that classifies aviation maintenance and inspection records against the governing CFR — the §91.207(c) battery expiration entry, the §91.207(d) 12-month inspection record, and the way ELT currency feeds the §91.417(a)(2) inspection status. It tracks the use-and-life-driven battery clock and the 12-calendar-month inspection clock separately, flags missing or mismatched entries, and generates an inspector-format audit binder on demand. It does not perform inspections, replace batteries, hold a certificate, or replace your A&P or repair station. Starter $89/month · Professional $299/month · 5-day free trial, no credit card required.
Chad Griffith
Founder, FileFlo — compliance document intelligence
FileFlo helps operators classify, index, and prove their compliance documents are audit-ready. This article is a compliance-document perspective on the 14 CFR §91.207 emergency locator transmitter requirements — it is not legal, airworthiness, or maintenance advice, and it does not replace an A&P mechanic, a repair station, or an FAA inspector. Always verify the current eCFR text for any regulatory decision.