If planning an IFR flight at 14,000 feet MSL off airways, what is the maximum leg length between a (HA) class and an (L) class NAVAID?

When planning an IFR flight off airways, it’s important to understand the operational limitations associated with different classes of navigational aids (NAVAID). The maximum leg length between a High Altitude (HA) class NAVAID and a Low Altitude (L) class NAVAID is determined by the service volume of the various classes of NAVAIDs.

For an IFR flight operating between these classes of NAVAIDs, the maximum leg length that can be maintained while ensuring adequate navigational reliability is 80 nautical miles (NM). This limit is crucial because it ensures that the aircraft can remain within the coverage and operational parameters of the NAVAIDs it is using for navigation.

Leg lengths beyond this defined maximum could result in reduced navigation accuracy and increased risk of losing reliable reference signals, which is particularly critical when flying in instrument conditions where visual references are limited.

Understanding the limitations of navigational aids is essential for IFR flight planning, especially when operating outside the confines of established airways. This knowledge ensures the safety and reliability of the flight by keeping aircraft within the prescribed service volumes of NAVAIDs.