Definition
The minimum forecast weather conditions required at an alternate airport, listed on an instrument flight plan, for a helicopter operating under instrument flight rules. When the destination weather may not support an instrument approach, regulations require filing an alternate, and the alternate's forecast ceiling and visibility at the estimated time of arrival must meet or exceed the published alternate minimums for that airport. For helicopters, the alternate minimums are typically a ceiling of 200 feet above the minimum descent altitude or decision altitude of the planned approach, and a visibility of at least 1 statute mile but never less than the approach minimums.
Plain English
If the weather at where you plan to land might be too poor to land, you must list a backup airport on your flight plan. This rule sets how good the forecast weather has to be at that backup airport, specifically when you're flying a helicopter under instrument rules.
Context Anchor
Seen when planning an IFR helicopter flight and deciding whether a listed alternate airport or heliport meets the required weather forecast.
Derivation
Alternate' comes from the Latin alternare, meaning 'to do by turns' — here, the airport you'd turn to if the first one doesn't work out. 'Minimums' is simply the lowest acceptable values. So the phrase reads naturally as 'the lowest weather still acceptable at the backup airport.'
Why Pilots Care
Determines whether a legal and safe diversion option exists, directly affecting whether an IFR flight can be filed and conducted.
Intuition Check
Alternate does not mean any place you might try later; it means the specific backup airport or heliport used for IFR planning. Minimums are not ideal weather—they are the lowest forecast weather allowed for that backup to count.
Example Sentence 1
Before filing IFR to the hospital helipad, the pilot checked the forecast at the nearby airport to confirm it met helicopter alternate minimums at the planned arrival time.
Example Sentence 2
With weather below minimums at the destination, the helicopter diverted to the alternate airport using the published helicopter alternate minimums.