FAA Airline Transport Pilot (ATM)Navigation, Air Traffic Control and ProceduresMedium
A dispatcher is filing an IFR flight plan for an airliner whose destination has only a non-precision approach available. To omit an alternate airport from the flight plan under the standard alternate minimums ('1-2-3' rule), the forecast weather at the destination for the period 1 hour before to 1 hour after the ETA must indicate at least what ceiling and visibility?
- A800 feet and 2 statute miles
- B600 feet and 2 statute miles
- C2,000 feet and 3 statute miles
- D1,000 feet and 3 statute miles
Show answer & explanationAnswer & explanation
Correct answer: C. 2,000 feet and 3 statute miles
Under 14 CFR 91.169(b)(1), an alternate is not required if, for at least 1 hour before through 1 hour after the ETA, the forecast ceiling is at least 2,000 feet and visibility at least 3 statute miles at an airport with a standard instrument approach.
Why the other options are wrong
- A. 800-2 is the standard alternate minimum for a non-precision approach, not the destination forecast threshold.
- B. 600-2 is a standard alternate minimum for a precision approach, not the 1-2-3 rule figure.
- D. 1,000-3 is not the correct combination used in the 1-2-3 rule.
1-2-3 Rule (Alternate Requirement)
Guideline under 91.169 for determining when an alternate airport must be listed on an IFR flight plan.
- 1 hour before to 1 hour after ETA forecast window
- 2,000-foot ceiling minimum
- 3 statute miles visibility minimum
Memory trick: 1 hour, 2,000 ceiling, 3 miles vis — that's the 1-2-3 fix.