When is a destination alternate required to be planned and listed on the dispatch release? (1-2-3 Rule)

When is a destination alternate required to be planned and listed on the dispatch release? (1-2-3 Rule)

• A. Only if forecast weather is bad
• B. 1 hour before or after ETA, ceilings less than 2,000 ft, visibility less than 3 SM
• C. If fuel is insufficient
• D. 2 hours before ETA only

Answer: (B)

The idea behind the 1-2-3 rule is to decide when you must plan a destination alternate based on forecast weather around your ETA. You check the destination’s forecast for a window from one hour before to one hour after your estimated arrival. If the weather within that window shows a ceiling below 2,000 feet or visibility below 3 statute miles, you are required to plan and list a destination alternate on the dispatch release. The 2,000-foot ceiling and 3-mile visibility represent conditions that would make a straight-in instrument landing risky, so having an alternate ensures there’s a safe option if you can’t land at the destination as planned. If the forecast meets or exceeds those minima, you generally don’t have to designate an alternate for weather reasons (though other factors could still create a need for an alternate).

The idea behind the 1-2-3 rule is to decide when you must plan a destination alternate based on forecast weather around your ETA. You check the destination’s forecast for a window from one hour before to one hour after your estimated arrival. If the weather within that window shows a ceiling below 2,000 feet or visibility below 3 statute miles, you are required to plan and list a destination alternate on the dispatch release. The 2,000-foot ceiling and 3-mile visibility represent conditions that would make a straight-in instrument landing risky, so having an alternate ensures there’s a safe option if you can’t land at the destination as planned. If the forecast meets or exceeds those minima, you generally don’t have to designate an alternate for weather reasons (though other factors could still create a need for an alternate).