During the ILS RWY 13 procedure at DSM, what is the minimum altitude if the glide slope becomes inoperative?

The correct minimum altitude, if the glide slope becomes inoperative during the ILS RWY 13 procedure at DSM, is based on the minimum altitude requirements for the approach without glide slope guidance. When the glide slope is not available, pilots follow a localizer approach, which typically has specific minimum altitudes to ensure safe navigation and clearance from obstacles.

In this case, the specified minimum altitude of 1,380 feet is in line with the necessary altitude that allows for a safe visual approach or transition to another navigation method while using the localizer. This altitude helps maintain a safe distance above the terrain and obstacles in the approach path, ensuring that the aircraft can navigate safely toward the runway.

Other altitudes suggested in the choices may not adhere to established aviation safety standards or may not correlate with the approach plate information, making them inappropriate for the situation where the glide slope is inoperative.