What is the ceiling and visibility requirement for an IFR Alternate when expecting less than 2000' ceiling and 3 statute miles visibility?

The ceiling and visibility requirement for an IFR alternate airport is crucial for ensuring that an aircraft can safely land if the primary destination is inaccessible due to weather conditions. When expecting less than a 2,000-foot ceiling and 3 statute miles of visibility at the time of the approach, there are specific time frames during which those conditions must be met at the alternate airport.

The correct answer stipulates that the weather conditions must be forecast to meet the minimum requirements one hour before and one hour after the estimated time of arrival (ETA). This requirement ensures that pilots have a safe decision-making buffer, allowing for changes in weather that could affect landing safety. The one-hour window provides enough flexibility in planning and increases safety by accounting for potential weather deteriorations or improvements.

This regulation is in place to help ensure that if a diversion is necessary, the alternate airport will indeed have the required weather conditions for a safe approach and landing when approached within that timeframe. The other choices suggest different time frames which do not meet the regulations set forth by aviation authorities, making them unsuitable for ensuring safety under IFR operations when facing marginal weather.