Direct Answer
Part 135 proving runs — the FAA calls them proving tests — are demonstration flights required by 14 CFR §135.145 before a certificate holder may operate an aircraft it has not previously proven: any aircraft other than a turbojet that requires two pilots for VFR, and any turbojet airplane. The rule sets a floor of at least 25 hours of proving tests acceptable to the Administrator, including five hours of night time if night is to be authorized, five instrument approaches if IFR is to be authorized, and entry into a representative number of en route airports.
You fly your actual aircraft with your actual crews and procedures while FAA inspectors observe. 14 CFR §135.145(c) prohibits carrying passengers during proving tests except those needed to make the tests and those designated by the Administrator to observe them — and pilot flight training may be conducted during the tests. Validation tests under §135.145(d) cover things like new aircraft additions, operations outside U.S. airspace, Class II navigation, and special authorizations.
Proving runs are part of the certification journey, not the end of it. When the FAA is satisfied, the result is reflected in your operations specifications, amended under 14 CFR §119.51. FileFlo doesn't fly the runs or get you certified — it keeps the proving-test records organized and provable.
This guide answers “what proving runs are and when they're required” as part of the certification journey. If you want the document-by-document deep dive on the evidence the tests produce and how to keep it audit-ready, read the companion piece on Part 135 aircraft proving and validation tests and the records they require.
Where Proving Runs Sit in the Certification Journey
Part 135 certification is a five-phase process, and proving runs land near the end of it. By the time you fly them, you have already submitted your formal application, had your manuals and training program accepted, and worked through document and demonstration phases with your certification team. Proving runs are the operational proof that what you wrote down actually flies — the bridge between an accepted paper application and an issued certificate with live operations specifications. For the full sequence around them, see how to get a Part 135 certificate and how long Part 135 certification takes.
This article walks the proving-run phase end to end: what proving runs are, when §135.145 makes them mandatory (and when it doesn't), what the tests actually involve, how validation tests differ, the records the phase generates, and what changes the moment the tests are accepted. Whether you certify with a consultant or run it in-house — a tradeoff we cover in Part 135 certification: consultant vs. DIY — the proving-run requirements in §135.145 are the same.
What Proving Runs Actually Are
The regulation uses the term proving tests; operators usually say proving runs or proving flights. They all mean the same thing: a block of demonstration flying, conducted under the supervision and observation of the FAA, in which a prospective or expanding Part 135 operator proves it can conduct a specific kind of operation, in a specific aircraft, safely and in compliance with the manuals, checklists, training, and procedures it has proposed.
The key word is proven. The text of 14 CFR §135.145(a) bars a certificate holder from operating an aircraft “if it has not previously proved such an aircraft in operations under this part in at least 25 hours of proving tests acceptable to the Administrator.” You are not flying to practice — you are flying to demonstrate, on the record, that the operation works as designed. Inspectors watch how your crews use the checklists, how dispatch and operational control function, how the aircraft is handled in the conditions you intend to operate, and whether reality matches the manuals.
Proving runs are a test of the system, not just the pilots
It is tempting to treat proving runs as a flying exam. They are broader than that. The FAA is validating your whole operation — manuals, training records, weight-and-balance control, maintenance interface, and especially operational control. A crew can fly beautifully and the tests can still surface gaps in the paper system the flights run on. That is exactly what proving runs are designed to catch before passengers are on board.
When Proving Runs Are Required — and When They Aren't
§135.145 has two proving triggers, and both are written around the aircraft and its crew requirement — not your company size or certificate label:
Two-pilot non-turbojet aircraft
Under §135.145(a), no certificate holder may operate an aircraft other than a turbojet, for which two pilots are required by the chapter for operations under VFR, if it has not previously proved such an aircraft under Part 135 in at least 25 hours of proving tests acceptable to the Administrator.
Turbojet airplanes
Under §135.145(b), no certificate holder may operate a turbojet airplane if it has not previously proved a turbojet airplane under Part 135 in at least 25 hours of proving tests acceptable to the Administrator. Every jet that is new ground for your certificate is in scope.
The practical takeaway: a single-pilot piston operation is generally outside both triggers, while a move up to a two-pilot turboprop or any jet brings §135.145 into play. Because the test is the aircraft, the same operator can need proving runs for one airplane and not another. Certificate type is a useful shorthand — and we break it down in Part 135 certificate types: single-pilot, basic, and standard — but the proving trigger lives in the text of §135.145, not the label.
Already operating? Adding a new aircraft can re-trigger it
Proving and validation tests aren't only an initial-certification event. Adding a two-pilot or turbojet aircraft your certificate has never proven can bring §135.145 back — while adding another tail of a make or similar design you already operate generally does not. That determination belongs to the FAA. We walk the mechanics in adding an aircraft to a Part 135 certificate.
What Proving Runs Involve: The 25 Hours, Night, IFR, and En Route Airports
Both proving triggers set the same floor — at least 25 hours of proving tests acceptable to the Administrator — and §135.145(a) and (b) each spell out specific elements those hours must include. The hour count is a minimum; the FAA can require more, and the elements scale to the authorizations you are requesting.
At least 25 hours
The minimum block of proving tests for a two-pilot non-turbojet or any turbojet not previously proven. Treat it as a floor — inspectors decide when they have seen enough to be satisfied across your kinds of operations.
14 CFR §135.145(a) & (b)
Five hours of night
Five hours of night time, if night flights are to be authorized. If you are not requesting night authority, this element keys off what you ask for.
14 CFR §135.145(a)(1) / (b)(1)
Five instrument approaches
Five instrument approach procedures under simulated or actual conditions, if IFR flights are to be authorized. IFR authority and the approaches that prove it travel together.
14 CFR §135.145(a)(2) / (b)(2)
Representative en route airports
Entry into a representative number of en route airports as determined by the Administrator — proving the operation in the airport environment you intend to use, not just at your home base.
14 CFR §135.145(a)(3) / (b)(3)
The no-passengers rule
14 CFR §135.145(c) is unambiguous: “No certificate holder may carry passengers in an aircraft during proving tests, except those needed to make the tests and those designated by the Administrator to observe the tests.” The same paragraph adds that pilot flight training may be conducted during the proving tests. So the only people on a proving flight are the crew and personnel required to run the demonstration plus the FAA observers — no revenue, and nobody just along for the ride. Carrying a paying passenger on a proving flight isn't a proving flight at all; it's an unauthorized revenue trip, the very thing the proving phase exists to earn the right to fly.
Why this matters beyond the test
Flying revenue passengers before your certificate and operations specifications authorize the operation is the heart of illegal-charter enforcement. Proving runs are the legitimate path to authorization — the opposite of the “grey charter” shortcut. For how the FAA frames the line between authorized and unauthorized carriage, see illegal charter and the FAA crackdown on grey charter.
Proving Tests vs. Validation Tests
§135.145 is titled “Aircraft proving and validation tests” — and the two are related but distinct. Proving tests, in paragraphs (a) and (b), prove a two-pilot non-turbojet aircraft or a turbojet airplane you have not previously proven. Validation tests, in paragraph (d), validate that an operation can be conducted safely and in compliance for a broader set of situations.
Proving tests — §135.145(a) & (b)
Prove a two-pilot non-turbojet aircraft, or a turbojet airplane, that the certificate holder has not previously proven under Part 135. At least 25 hours, with the night, IFR, and en route elements scaled to the authorizations requested.
Validation tests — §135.145(d)
Required for things such as the addition of a two-pilot (VFR) or turbojet aircraft where that aircraft or one of the same make or similar design has not been previously proven or validated, operations outside U.S. airspace, Class II navigation, and special performance or operational authorizations.
Methods & flights — §135.145(e)
Tests must use methods acceptable to the Administrator, and actual flights may not be required when an applicant can demonstrate competence and compliance with the appropriate regulations without conducting a flight.
Run together — §135.145(f)
Proving tests and validation tests may be conducted simultaneously when appropriate — so a single block of demonstration flying can satisfy both where the FAA agrees it fits.
One practical note: because §135.145(e) lets the FAA accept a demonstration of competence and compliance without an actual flight in defined cases, not every validation requirement means more flight hours. Whether a given authorization needs flying, a tabletop demonstration, or documentation is a fact-specific call for your Flight Standards office — never assume it away, and never assume it's required either.
Is your proving-test evidence organized?
Run a free FAA readiness check to see how your records stack up against what the proving-test phase — and your operations specifications — expect.
The Records Proving Runs Generate
Proving runs are an evidence-producing event. The flights themselves matter, but what survives them is a stack of documents the FAA relies on to issue or amend your authorization — and that you carry forward as part of your permanent compliance record. This is where the proving phase quietly becomes a recordkeeping phase.
| Record | What it proves |
|---|---|
| Proving-test plan & FAA correspondence | The agreed scope, hours, elements (night/IFR/en route), and conditions of the tests, plus the FAA approval and acceptance trail. |
| Proving-flight logs & records | The actual hours flown, night time, instrument approaches, and airports entered — the evidence the §135.145 elements were met. |
| Crew qualification & training records | That the pilots flying the proving runs were trained, checked, and qualified for the operation being proven. |
| Manuals, checklists & procedures | The exact operational documents the runs validated — the version proven is the version you are then authorized to operate. |
| Aircraft airworthiness & weight-and-balance | That the specific aircraft was airworthy, properly configured, and within limits during the demonstration. |
| Operations specifications revision | The §119.51 amendment that reflects what you proved — the authorization the proving runs earned. |
Two things make this stack matter long after certification. First, the version of the manuals and checklists you prove is the version you are authorized to operate — so version control of those documents is a compliance issue, not a formality. Second, the proving-flight records and crew qualifications become part of the recordkeeping you are obligated to maintain as an operator. For the full picture of what you have to keep and for how long, see what records a Part 135 operator must keep and the document-by-document companion on proving and validation test records.
Where FileFlo fits — and where it doesn't
FileFlo is the compliance document intelligence layer underneath the proving-run phase. It classifies, indexes, version-tracks, and surfaces expirations on the records the runs generate and depend on — the proving-test plan and FAA correspondence, the proving-flight logs, crew qualification and training records, the manuals and checklists you are proving, the airworthiness and weight-and-balance documents, and the operations specifications revision that follows. When the FAA asks for the package, every document is classified, current, and retrievable in one place — and after the tests, the expirations that keep the operation legal are tracked before they lapse.
What FileFlo does not do: fly your proving runs, schedule them with your FSDO, write or amend your manuals and training program, decide whether an aircraft triggers §135.145, get you certified, or give legal or tax advice. Those belong to your management team, your crews, the FAA, and your advisors. FileFlo organizes and proves the records — it is not the operation, the certificate, or your counsel. (FileFlo does not claim SOC 2 certification.)
After Proving Runs: From Demonstration to Authorization
Proving runs don't authorize anything by themselves — they are the evidence that supports issuing or amending your authorization. When the FAA is satisfied the proving (and any validation) tests demonstrate a safe, compliant operation, that result is reflected in your operations specifications: the OpSpecs authorize the kind of operation, the aircraft, the areas, and the conditions you proved.
Operations specifications are amended under 14 CFR §119.51, and 14 CFR §119.5 makes operating without, or in violation of, appropriate operations specifications a violation in its own right. So the sequence is: prove the operation, the FAA accepts the evidence, the OpSpecs are amended to authorize it — and only then can you carry revenue passengers in that aircraft on that kind of operation. Skipping to the last step before the OpSpecs catch up is operating outside your authorization.
For everything that wraps around the proving phase — the application package, the phases before it, and the documents the FAA reviews — see the Part 135 certification application checklist and how to get a Part 135 certificate.
Keep reading — the Part 135 “how to operate” cluster
Part 135 Proving Runs — Frequently Asked Questions
Q.What are Part 135 proving runs?
Proving runs (the FAA calls them proving tests) are demonstration flights a prospective or expanding Part 135 operator flies for the FAA during certification to prove it can operate a particular aircraft safely and in compliance with its proposed manuals, training, and operations specifications. They are required by 14 CFR §135.145. The applicant flies its actual aircraft, with its actual crews and procedures, while FAA inspectors observe — proving the paper certificate works in the air before any paying passenger gets on board. Proving tests are flown without revenue passengers and culminate in the operations specifications authorization to conduct that kind of operation.
Q.When are proving runs required for Part 135?
Under 14 CFR §135.145, proving tests are required before a certificate holder may operate two categories of aircraft it has not previously proven under Part 135: (a) any aircraft other than a turbojet for which two pilots are required for VFR operations, and (b) any turbojet airplane. So a single-pilot piston airplane on a basic single-pilot certificate generally does not trigger §135.145, while moving up to a two-pilot turboprop or any jet does. The trigger is the aircraft, not the company — the question is whether you (or an aircraft of the same make or similar design) have already proven that class of airplane under your certificate. New types, and the addition of a never-before-proven two-pilot or turbojet aircraft, bring proving or validation tests back into play.
Q.How many hours of proving runs does Part 135 require?
Both §135.145(a) and §135.145(b) set the floor at “at least 25 hours of proving tests acceptable to the Administrator.” Within those 25 hours, §135.145 calls out specific elements: five hours of night time if night flights are to be authorized, and five instrument approach procedures under simulated or actual conditions if IFR flights are to be authorized, plus entry into a representative number of en route airports as determined by the Administrator. Twenty-five hours is a regulatory minimum, not a target — the FAA can require more, and the real number is whatever it takes for inspectors to be satisfied the operation is safe and compliant across the kinds of operations you are requesting.
Q.What is the difference between proving tests and validation tests?
They are two halves of §135.145 and they answer different questions. Proving tests under §135.145(a) and (b) prove a two-pilot non-turbojet aircraft or a turbojet airplane the certificate holder has not previously proven. Validation tests under §135.145(d) validate that an operation can be conducted safely and in compliance for things like adding an aircraft for which two pilots are required for VFR (or a turbojet) where that aircraft or one of the same make or similar design has not been previously proven or validated, operations outside U.S. airspace, Class II navigation, and special performance or operational authorizations. Under §135.145(e) the tests use methods acceptable to the Administrator, and actual flights may not be required when an applicant can demonstrate competence and compliance without conducting a flight. Under §135.145(f) proving and validation tests may be conducted simultaneously when appropriate.
Q.Can you carry passengers during Part 135 proving runs?
No. 14 CFR §135.145(c) prohibits a certificate holder from carrying passengers in an aircraft during proving tests, except those needed to make the tests and those designated by the Administrator to observe the tests. The same paragraph allows pilot flight training to be conducted during the proving tests. In plain terms: no revenue, no friends, no family — only the people required to run the demonstration and the FAA inspectors and observers. Putting a paying passenger on a proving flight is operating a revenue trip without the authorization the proving runs exist to earn.
Q.Do proving runs apply to a single-pilot or basic Part 135 certificate?
Usually not, because of how §135.145 is scoped. The rule reaches aircraft other than turbojets only when two pilots are required for VFR operations, plus all turbojet airplanes. A classic single-pilot certificate built around one piston airplane flown single-pilot generally falls outside both triggers, so no proving runs. The picture changes the moment the aircraft does: add a turbojet, or an airplane your operation must crew with two pilots, and §135.145 attaches. Certificate type (single-pilot, single-pilot-in-command, basic, standard) is a useful shorthand, but the proving-test trigger is written around the aircraft and its crew requirement, not the label on your certificate — so always test the specific airplane against §135.145, not the certificate name.
Q.What happens after proving runs are complete?
When the FAA is satisfied the proving (and any validation) tests demonstrate a safe, compliant operation, that result is reflected in your operations specifications — the OpSpecs authorize the kind of operation, aircraft, and areas you proved. Operations specifications are amended under 14 CFR §119.51, and §119.5 makes operating without, or in violation of, appropriate operations specifications a violation in its own right. So proving runs are not the finish line by themselves; they are the evidence that supports issuing or amending the authorization. Until the OpSpecs reflect what you proved, you are not authorized to carry revenue passengers in that aircraft on that kind of operation.
Q.Does FileFlo fly proving runs or get me my Part 135 certificate?
No. FileFlo does not fly proving runs, schedule them with your FSDO, write your training program, or get you certified — those belong to your management team, your crews, and the FAA. FileFlo is the compliance document layer underneath the proving-test phase: it classifies, version-tracks, and surfaces the records the proving runs generate and depend on, so the proving-test package is organized, current, and provable. That includes the proving-test plan and FAA correspondence, flight logs and proving-flight records, crew qualification and training records, the manuals and checklists you are proving, and — after the tests — the operations specifications revision that authorizes the operation. FileFlo keeps that evidence audit-ready; it does not provide legal, tax, or certification services.
This article is general compliance-document information, not legal or tax advice. Whether a specific aircraft triggers proving or validation tests under 14 CFR §135.145, how the hours and elements are structured, and how your operations specifications are amended are fact-specific determinations made by the FAA — confirm every detail against the current text of 14 CFR §135.145, 14 CFR §119.51, your draft operations specifications, and your assigned Flight Standards office. For legal questions, consult an aviation attorney; for tax questions, consult a tax advisor. FileFlo organizes and proves compliance records; it does not fly proving runs, structure your operation, decide operational control, or get you certified, and it does not claim SOC 2 certification.
Make the proving-test phase a records strength, not a scramble
FileFlo keeps the proving-test plan, flight logs, crew qualifications, manuals, and the operations specifications revision classified, current, and provable — so when the FAA asks, your evidence is one search away. You fly the runs and earn the certificate; FileFlo keeps the proof in order.