FAA Airline Transport Pilot (ATM)Regulations (14 CFR 117/121/61)Medium
A dispatcher evaluating a Part 121 domestic flight to an airport with one usable instrument approach finds that from 1 hour before to 1 hour after the estimated time of arrival, the forecast ceiling is 2,500 feet and visibility is 4 statute miles. Under 14 CFR 121.617, is a destination alternate airport required?
- ANo, alternates are only required for flag (international) operations
- BNo, because the forecast meets the standard 2,000-foot ceiling and 3-mile visibility alternate-not-required minimums
- CYes, an alternate is always mandatory for domestic operations
- DYes, because the ceiling is below 3,000 feet
Show answer & explanationAnswer & explanation
Correct answer: B. No, because the forecast meets the standard 2,000-foot ceiling and 3-mile visibility alternate-not-required minimums
Under 121.617, an alternate is not required if, for at least 1 hour before through 1 hour after the ETA, the appropriate weather reports/forecasts indicate the ceiling will be at least 2,000 feet and visibility at least 3 statute miles. Here, 2,500 ft/4 sm exceeds both minimums, so no alternate is required.
Why the other options are wrong
- A. Domestic operations also have alternate-not-required provisions, so this is false.
- C. Alternates are not always mandatory; the 1-2-3 style rule allows exceptions.
- D. 2,500 feet exceeds the 2,000-foot threshold, so this reasoning is incorrect.
Destination Alternate Not Required Rule
14 CFR 121.617 allows omission of a destination alternate when forecast weather around ETA meets specified ceiling/visibility minimums.
- Window: 1 hour before to 1 hour after ETA
- Minimums: ceiling ≥2,000 ft, visibility ≥3 statute miles
- Applies when destination has at least one operational instrument approach
Memory trick: "2,000 and 3 — no alternate for me."