For straight-in approaches, what vital information must be provided by the controller?

For straight-in approaches, providing the straight-in Minimum Descent Altitude (MDA) is crucial because it sets the minimum altitude to which a pilot can descend during an approach when the required visual references are not available. This altitude is essential for ensuring safety, as it dictates the lowest point an aircraft can fly while still being able to execute a safe landing if necessary.

Correctly informing pilots of the MDA allows them to manage their descent profile and decision-making during the approach. If pilots reach this altitude without visual reference to the runway or if the required visual cues are not visible, they must execute a missed approach to ensure the aircraft's safety. This information becomes even more vital in low visibility conditions, where pilots rely heavily on instruments.

While the localizer frequency, heading for landing, and missed approach procedures are also relevant to the successful completion of an approach, the straight-in MDA is critical for defining the safe altitude limits during the approach itself.