Which correctly defines DA and DH?

Which correctly defines DA and DH?

• A. Distance Altitude and Distance Height
• B. Dynamic Altitude and Dynamic Height
• C. Depth Altitude and Depth Height
• D. Decision Altitude (MSL) and Decision Height (AGL)

Answer: (D)

When flying an instrument approach, you reach a defined point where you must decide whether you can land or need to go around. That point is described by two terms that use different reference references: altitude above mean sea level (MSL) and height above the airport. Decision Altitude is the altitude expressed in feet MSL at which you must decide to continue the approach and land if you have the necessary visual conditions. If you don’t have them by then, you execute a missed approach. Decision Height is the corresponding height above the airport’s elevation (height above ground, or AGL) at which the same decision point applies for other types of approaches. In practice, these two figures line up to tell you, relative to sea level and relative to the airfield ground, where the decision point lies. For example, if the airport elevation is 2,000 feet MSL and the DA is 2,400 feet MSL, you must decide by that point based on sea-level reference. If instead the chart uses a DH of 400 feet AGL, you would be considering 2,400 feet MSL as well when you subtract the airport elevation, aligning the same decision point with a height above the runway. The other option presents terms that aren’t standard aviation definitions, so they don’t describe the official decision-point concepts used on instrument approaches.

When flying an instrument approach, you reach a defined point where you must decide whether you can land or need to go around. That point is described by two terms that use different reference references: altitude above mean sea level (MSL) and height above the airport.

Decision Altitude is the altitude expressed in feet MSL at which you must decide to continue the approach and land if you have the necessary visual conditions. If you don’t have them by then, you execute a missed approach.

Decision Height is the corresponding height above the airport’s elevation (height above ground, or AGL) at which the same decision point applies for other types of approaches. In practice, these two figures line up to tell you, relative to sea level and relative to the airfield ground, where the decision point lies.

For example, if the airport elevation is 2,000 feet MSL and the DA is 2,400 feet MSL, you must decide by that point based on sea-level reference. If instead the chart uses a DH of 400 feet AGL, you would be considering 2,400 feet MSL as well when you subtract the airport elevation, aligning the same decision point with a height above the runway.

The other option presents terms that aren’t standard aviation definitions, so they don’t describe the official decision-point concepts used on instrument approaches.