Definition
Helicopter IFR Alternates are the alternate airport requirements that apply specifically to helicopter operations conducted under instrument flight rules. When a helicopter pilot files an IFR flight plan, an alternate must be filed unless the destination weather forecast, for at least one hour before through one hour after the estimated time of arrival, indicates a ceiling of at least 1,000 feet above the lowest published approach minimum, or 400 feet above the lowest applicable approach minimum (whichever is higher), and visibility of at least 2 statute miles. Required alternate weather minimums for a helicopter are a ceiling of at least 200 feet above the alternate's published minimum and visibility of at least 1 statute mile, but never less than 1/2 statute mile.
Plain English
These are the rules that tell a helicopter pilot when they must list a backup airport on their IFR flight plan, and what the weather has to look like at that backup airport for it to count. The rules are different from the ones used for airplanes.
Context Anchor
Seen during helicopter instrument flight planning, especially when deciding whether an alternate must be listed on the IFR flight plan and whether that alternate has acceptable forecast weather.
Derivation
Alternate comes from the Latin idea of doing something by turns or using another option. In flight planning, it means the other place you plan to use if the first destination does not work out. IFR means instrument flight rules, the rules used when the pilot may need to fly by instruments instead of outside visual references.
Why Pilots Care
Provides the legal and practical options required to continue or safely divert an IFR helicopter flight when conditions at the destination deteriorate.
Intuition Check
Alternate does not mean any convenient place you might decide to land later. In IFR planning, it means a specific backup airport or heliport that meets the required forecast weather rules before the flight begins.
Example Sentence 1
Because the destination forecast showed a ceiling of only 800 feet at the ETA, the pilot applied the helicopter IFR alternate rules and filed a nearby heliport with a forecast 300-foot ceiling and 1 mile visibility.
Example Sentence 2
During preflight planning the crew confirmed two suitable helicopter IFR alternates before departing on the instrument cross-country.