14 CFR 91.169 — IFR Flight Plan: Information Required
Specifies IFR flight plan requirements and the conditions under which an alternate airport must be listed.
Regulation Text
Unless otherwise authorized by ATC, each person filing an IFR flight plan must include information required by ATC. For filing purposes, an alternate airport need not be included if: for at least 1 hour before and 1 hour after the estimated time of arrival, the weather at the destination airport is forecast to have a ceiling of at least 2,000 feet above the airport elevation and visibility of at least 3 statute miles.
Note: This is an excerpt. Refer to the full regulation in eCFR for the complete text.
Plain-English Explanation
The 1-2-3 rule: you need to file an alternate airport on your IFR flight plan UNLESS the destination weather is forecast to be at least a 2,000-foot ceiling and 3-mile visibility from 1 hour before to 1 hour after your ETA. Remember it as 1 hour, 2,000 feet, 3 miles = 1-2-3. If you do need an alternate, it must have weather good enough for an approach (typically 600-2 for precision, 800-2 for non-precision). This is one of the most frequently tested IFR regulations.
Tested On These Exams
Related Regulations
14 CFR 91.167 — Fuel Requirements for Flight in IFR Conditions
IFR fuel: enough to fly to destination, then to alternate (if required), then 45-minute reserve at normal cruising speed.
§91.10314 CFR 91.103 — Preflight Action
PIC must familiarize themselves with all available information concerning the flight, including weather, fuel requirements, alternatives, runway lengths, and performance data.
§91.17514 CFR 91.175 — Takeoff and Landing Under IFR
Rules for when a pilot may descend below MDA/DA on an instrument approach, including required flight visibility and visual references.
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