At what altitude are VOR navigational requirements typically relaxed?

The standard for VOR navigational requirements typically indicates that below 10,000 feet mean sea level (MSL), the operational accuracy and signal reception are generally more lenient compared to higher altitudes. The reason for this relaxation is primarily due to the fact that lower altitudes allow for better reception of VOR signals, which can be influenced by terrain structures and other obstacles at lower elevations. This is especially relevant in areas where mountains or buildings may obstruct the signal, but at lower altitudes, aircraft are often closer to the VOR stations, enhancing signal strength and reliability.

In contrast, the other altitude thresholds, such as above 24,000 feet MSL or at Flight Level 180 (FL 180), tend to impose stricter navigational accuracy requirements. These altitudes involve considerations for increased air traffic, potential interference, and a wider range of navigational aids that necessitate more precise navigation techniques. The absence of altitude relaxations also emphasizes that VOR requirements remain consistent across all flight levels, underscoring the importance of maintaining navigational accuracy at all times.