FAR 91.167 — IFR Fuel Requirements
FAR 91.167 sets minimum fuel for IFR flight: destination, alternate, plus 45 minutes reserve. Learn the rule, exceptions, and oral exam answers.
In Plain English
FAR 91.167 sets the minimum fuel you must carry to legally fly in IFR conditions. Considering current weather reports and forecasts, your aircraft must have enough fuel to:
- Fly to the first airport of intended landing
- Fly from there to the alternate airport (when one is required)
- Fly an additional 45 minutes at normal cruising speed (30 minutes for helicopters)
You don't have to carry fuel to an alternate if both of these are true:
- A standard or special instrument approach is published for the destination, and
- Weather forecasts show acceptable conditions at arrival. There are two versions of this exemption — commonly remembered as the "1-2-3 rule" in pilot training:
- From 1 hour before to 1 hour after ETA: ceiling ≥ 2,000 ft above airport elevation and visibility ≥ 3 SM, or
- At ETA and for 1 hour after: ceiling ≥ 1,000 ft above airport elevation or 400 ft above the lowest approach minima (whichever is higher) and visibility ≥ 2 SM.
Why it matters: weather can deteriorate, approaches can fail, and ATC can hold you. Adequate IFR fuel reserves keep you legal and, more importantly, give you options when plans change.
Regulation Text
14 CFR § 91.167§ 91.167 Fuel requirements for flight in IFR conditions.
(a) No person may operate a civil aircraft in IFR conditions unless it carries enough fuel (considering weather reports and forecasts and weather conditions) to—
(1) Complete the flight to the first airport of intended landing;
(2) Except as provided in paragraph (b) of this section, fly from that airport to the alternate airport; and
(3) Fly after that for 45 minutes at normal cruising speed or, for helicopters, fly after that for 30 minutes at normal cruising speed.
(b) Paragraph (a)(2) of this section does not apply if:
(1) Part 97 of this chapter prescribes a standard instrument approach procedure to, or a special instrument approach procedure has been issued by the Administrator to the operator for, the first airport of intended landing; and
(2) Appropriate weather reports or weather forecasts, or a combination of them, indicate the following:
(i)For at least 1 hour before and for 1 hour after the estimated time of arrival, the ceiling will be at least 2,000 feet above the airport elevation and the visibility will be at least 3 statute miles.
(ii)At the estimated time of arrival and for 1 hour after the estimated time of arrival, the ceiling will be at least 1,000 feet above the airport elevation, or at least 400 feet above the lowest applicable approach minima, whichever is higher, and the visibility will be at least 2 statute miles.
[Docket 98-4390, 65 FR 3546, Jan. 21, 2000]
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You are flying VFR in Class E airspace at 8,500 feet MSL during the day. What are your minimum visibility and cloud clearance requirements?
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Oral Exam Questions a DPE Might Ask
Q1What are the IFR fuel requirements for an airplane under Part 91?
Per FAR 91.167, you must carry enough fuel to fly to the first airport of intended landing, then to the alternate (if required), and then fly for 45 minutes at normal cruising speed.
Q2When are you not required to file an alternate airport for an IFR flight?
Under FAR 91.167(b), no alternate is required if a standard or special instrument approach is published for the destination and forecast weather from 1 hour before to 1 hour after ETA shows a ceiling of at least 2,000 feet above airport elevation and visibility of at least 3 statute miles.
Q3How do the IFR fuel reserves differ for helicopters?
FAR 91.167(a)(3) requires helicopters to carry only a 30-minute reserve at normal cruising speed after reaching the destination or alternate, instead of the 45 minutes required for airplanes.
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VFR Weather Minimums
§91.155 visibility & cloud clearance by airspace
§91.117 Aircraft Speed Limits
250-kt, 200-kt, Class B shelf, and Class C/D airport caps
ATOMATOFLAMES Checklist
§91.205 required equipment for VFR day & night
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Related Sections in Part 91