FAA Instrument Rating Airplane (IRA)Regulations and CurrencyMedium
A pilot files an IFR flight plan with an ETA of 2000Z. The forecast for the destination from 1900Z to 2100Z calls for a ceiling of 2,000 feet broken and visibility 3 statute miles, with the airport having a standard instrument approach procedure. Is an alternate airport required to be filed?
- AYes, because visibility is not greater than 3 statute miles
- BNo, because the forecast only needs to meet minimums at the ETA itself
- CYes, because the ceiling is below 3,000 feet
- DNo, because forecast ceiling and visibility exactly meet the 1-2-3 rule minimums
Show answer & explanationAnswer & explanation
Correct answer: D. No, because forecast ceiling and visibility exactly meet the 1-2-3 rule minimums
Under 14 CFR 91.169(b), no alternate is required if, for at least 1 hour before to 1 hour after ETA, the forecast ceiling is at least 2,000 feet AND visibility is at least 3 statute miles. A forecast of exactly 2,000 ft/3 SM satisfies 'at least,' so no alternate is required.
Why the other options are wrong
- A. Incorrect — 3 SM meets the 'at least 3 SM' requirement exactly.
- B. Incorrect — the rule requires the 1-hour-before to 1-hour-after window, not just the ETA moment.
- C. Incorrect — 2,000 ft meets the 'at least 2,000 ft' threshold exactly.
1-2-3 Rule Exact Minimums
91.169(b) requires forecast ceiling at least 2,000 ft AND visibility at least 3 SM for the period surrounding ETA to avoid needing an alternate; meeting these exactly is sufficient.
- Window is 1 hr before to 1 hr after ETA
- 'At least' means equal values satisfy the rule
- Both ceiling and visibility must be met simultaneously
Memory trick: 2,000 and 3 — meet it exactly and you're free.