Part 135 IFR Fuel, Alternate & Weather Minimums
The Operating Limits — and the Records That Prove You Met Them

Where These Rules Live in Part 135

The fuel, weather, and minimum rules sit in Subpart D of Part 135 — the flight-operations subpart — and they interlock. The VFR rules (§§135.205, 135.209, 135.211) govern visual operations; the IFR rules (§§135.223, 135.225) govern instrument operations; and §135.213 sits across both, defining which weather products an operator may rely on for any of these decisions. None of them is a recordkeeping rule on its face. But each one creates a decision — how much fuel, which alternate, whether to start the approach — and every decision is reconstructable only from documents. That is the throughline of this guide: the operating limit is the regulation, and the proof you applied it is a compliance document.

That distinction matters because Part 135 records inspections do not just check that records exist — they check that the records substantiate the way the operation was actually flown. For the broader inventory of what a charter operator must retain, see what records a Part 135 operator must keep, and for the certificate-level authorizations that frame these limits — including the operations specifications that can tighten or, in narrow cases, modify them — see operations specifications (OpSpecs) explained.

IFR Fuel and the Alternate-Airport Requirement (§135.223)

Section 135.223 is the IFR fuel rule, and its structure is frequently misremembered as "destination plus 45 minutes." It is not. Paragraph (a) builds the required fuel in three stacked legs. No person may operate an aircraft in IFR conditions unless it carries enough fuel — considering weather reports and forecasts and weather conditions — to do all three of the following:

Read the three legs together and the rule is clear: destination, then the full distance to the alternate, then a reserve of 45 minutes (airplanes) or 30 minutes (helicopters) on top of the alternate leg. The reserve is computed at normal cruising speed and consumption — not at holding fuel flow, and not from the destination. Getting the order right is the whole point: an operator who plans destination plus a 45-minute reserve, but forgets the leg to the alternate, has under-fueled the flight under §135.223(a) even though it "carried 45 minutes of reserve."

The §135.223(b) exception — when the alternate leg drops out

Paragraph (b) is the only way the alternate leg — paragraph (a)(2) — comes out of the fuel calculation. It is a two-pronged forecast test, and both prongs must be satisfied. Paragraph (a)(2) does not apply if:

Two related notes round out the IFR fuel picture. First, the alternate that paragraph (a)(2) sends you to is itself subject to selection criteria built around the same kind of forecast logic, and the operations specifications can prescribe how alternates are chosen — another reason OpSpecs sit upstream of the daily fuel decision. Second, the fuel calculation presumes accurate aircraft performance and weight data; an out-of-date weight and balance record can quietly invalidate a fuel plan that looked correct on paper.

VFR Fuel, Visibility Minimums, and Over-the-Top (§§135.209, 135.205, 135.211)

The VFR side of Subpart D has its own set of numbers, and they are different from the IFR figures — the single most common conflation in this corner of the regulations. Section 135.209 sets the VFR fuel reserves. Under §135.209(a), no person may begin a flight operation in an airplane under VFR unless — considering wind and forecast weather conditions — it has enough fuel to fly to the first point of intended landing and, assuming normal cruising fuel consumption, to fly after that for at least 30 minutes during the day or at least 45 minutes at night. Under §135.209(b), the helicopter figure is at least 20 minutes after the first point of intended landing, day or night.

VFR weather minimums on top of Part 91 (§135.205)

Section 135.205 layers Part 135 weather minimums on top of the basic Part 91 VFR weather minimums. The text is specific. Under §135.205(a), no person may operate an airplane under VFR in uncontrolled airspace when the ceiling is less than 1,000 feet unless flight visibility is at least 2 miles. Under §135.205(b), no person may operate a helicopter under VFR in Class G airspace at an altitude of 1,200 feet or less above the surface — or within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport — unless the visibility is at least 1/2 mile during the day or 1 mile at night.

VFR over-the-top carrying passengers (§135.211)

Section 135.211 limits VFR over-the-top operations when passengers are aboard. Subject to any additional limitations in §135.181, no person may operate an aircraft under VFR over-the-top carrying passengers unless the weather reports or forecasts, or a combination of them, indicate that the weather at the intended point of descent from over-the-top will permit a descent to beneath the ceiling under VFR and is forecast to remain so until at least one hour after the estimated time of arrival at the destination — or, in the alternative, the conditions allow conducting an IFR approach with the flight clear of clouds until reaching the prescribed initial approach altitude. The section also addresses the aircraft's performance capability to descend, or continue, under VFR if an engine fails. Section 135.181 is the related operating-limitation rule on flight outside the operating range of navigational aids and over-the-top without an IFR capability, which is why §135.211 expressly cross-references it.

IFR Approach Minimums and Weather Sources (§§135.225 and 135.213)

Section 135.225 governs when an IFR approach may be begun and continued. Under §135.225(a), except to the extent permitted by paragraphs (b) and (j), no pilot may begin an instrument approach procedure to an airport unless both of two conditions are met:

Two carve-outs sit alongside the general rule. Paragraph (b) allows a pilot conducting an eligible on-demand operation to begin and conduct an instrument approach to an airport that does not have one of those weather reporting facilities, under conditions the paragraph specifies. Paragraph (j) addresses operations using an operable enhanced flight vision system (EFVS) in accordance with §91.176 and the certificate holder's authorizations. Both are narrow and authorization-dependent — they are not a general license to fly approaches without weather.

The 100-hours-in-type increase (§135.225(e))

Section 135.225(e) raises the bar for a less-experienced captain. The MDA or DA/DH and visibility landing minimums prescribed in Part 97 of the chapter, or in the operator's operations specifications, are increased by 100 feet and 1/2 mile respectively — but not to exceed the ceiling and visibility minimums for that airport when used as an alternate airport — for each pilot in command of a turbine-powered airplane who has not served at least 100 hours as pilot in command in that type of airplane.

Acceptable weather sources (§135.213)

Section 135.213 defines which weather products satisfy every fuel, alternate, and approach rule above. Under §135.213(a), whenever a person operating an aircraft under Part 135 is required to use a weather report or forecast, that person must use one prepared by the U.S. National Weather Service, a source approved by the U.S. National Weather Service, or a source approved by the Administrator — except that, for operations under VFR, the pilot in command may, if such a report is not available, use weather information based on that pilot's own observations or those of other persons competent to supply appropriate observations. Under §135.213(b), weather observations made and furnished to pilots to conduct IFR operations at an airport must be taken at the airport where those IFR operations are conducted, unless the Administrator issues operations specifications allowing observations taken at a location not at that airport.

The §135.213 source rule is the connective tissue of this whole subpart. The §135.223(b) decision to skip the alternate, the §135.225(a) decision to begin the approach, and the §135.205 and §135.209 VFR decisions all rest on weather information — and §135.213 is what makes that information count. A fuel or approach decision built on an unapproved weather source is exposed even if the numbers were otherwise fine, which is why a defensible operation retains the weather product alongside the trip paperwork rather than discarding it once the flight is complete.

What Actually Gets Documented — and How FileFlo Tracks It

None of §§135.205, 135.209, 135.211, 135.213, 135.223, or 135.225 is, on its face, a recordkeeping section — they are operating limits. But each one produces or depends on a document, and those documents are exactly what surveillance samples. Here is the record set that proves these limits were applied, and how a compliance document platform handles each class. Note the honest scope: FileFlo is the proof layer; it does not plan flights, compute fuel, pull weather, or exercise operational control.

This record trail does not sit in isolation. The same trip files that prove fuel and weather decisions are sampled alongside flight locating records, load manifests, and crew records — see the flight locating and flight release records guide and operational control in Part 135. And when the next records inspection lands, the fuel and weather records are sampled with everything else — the surveillance audit preparation guide walks through how those visits actually unfold, and the SMS records the operator will need under the Part 5 SMS deadline in 2027 run on exactly this kind of flight-risk and weather data.

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