What is the lowest altitude at which an intersection can be determined by a NAVAID?

What is the lowest altitude at which an intersection can be determined by a NAVAID?

• A. Minimum Safe Altitudes (MSA)
• B. Minimum Vectoring Altitudes (MVA)
• C. Minimum Crossing Altitude (MCA)
• D. Minimum Reception Altitude (MRA)

Answer: (D)

The key idea is whether you can reliably receive the navigation signal to locate a defined point. The lowest altitude at which you can still receive a NAVAID signal well enough to determine an intersection is the Minimum Reception Altitude. Above this altitude the signal is present and you can use the NAVAID data (radials, DME, etc.) to pinpoint the intersection. Below it, reception might be unreliable due to distance or terrain, so you wouldn’t be able to determine the intersection accurately. The other terms relate to different concepts: minimum safe altitude deals with obstacle clearance, minimum vectoring altitude is for radar vectoring, and minimum crossing altitude is the altitude to cross a fix or airway—none of these describe the point at which a NAVAID signal can be used to determine an intersection.

The key idea is whether you can reliably receive the navigation signal to locate a defined point. The lowest altitude at which you can still receive a NAVAID signal well enough to determine an intersection is the Minimum Reception Altitude. Above this altitude the signal is present and you can use the NAVAID data (radials, DME, etc.) to pinpoint the intersection. Below it, reception might be unreliable due to distance or terrain, so you wouldn’t be able to determine the intersection accurately. The other terms relate to different concepts: minimum safe altitude deals with obstacle clearance, minimum vectoring altitude is for radar vectoring, and minimum crossing altitude is the altitude to cross a fix or airway—none of these describe the point at which a NAVAID signal can be used to determine an intersection.