In the VHF band, which radio contact is least likely to be affected by attenuation?

In the VHF band, the phenomenon of attenuation refers to the weakening of radio signals as they travel through the atmosphere, which can be influenced by various factors such as distance, obstacles, and frequency. When considering the options provided, two aircraft in contact with each other at 30,000 ft are least likely to experience significant attenuation.

At this altitude, the line of sight between the two aircraft is more direct and less obstructed compared to communications at lower altitudes. Higher altitudes generally reduce the impact of ground-based obstructions such as buildings, terrain, and vegetation, which can cause greater signal degradation. Moreover, as altitude increases, the atmosphere has thinner air, resulting in reduced attenuation effects.

In contrast, other scenarios, such as an aircraft in contact with a ground station or ground stations communicating with one another, may encounter more interference from various forms of environmental factors, such as buildings or terrain, which can scatter or absorb radio waves, thereby leading to increased attenuation. This is particularly true for communication between aircraft at lower altitudes, which may face additional challenges from obstacles in the environment.

Therefore, communications between two aircraft at a higher altitude, like 30,000 ft, are not only more direct but also less prone to attenuation,