Should an Installed VOR Be Required for Approach in Terrain Area Airports?

The necessity of an installed VOR (VHF Omnidirectional Range) in a terrain area airport for approach operations depends largely on weather conditions, aircraft capabilities, and navigation technologies available. While VORs are historically significant and still used, current advancements in navigation technology have made alternatives like RNAV/GPS much more viable options.

Historical Context and Limitations of VORs

VORs are government-installed as part of the airway system and have been used for over 50 years. However, they are considered onerous old technology. In the USA, many VORs are currently being decommissioned as part of a strategic reduction in the network to ensure navigation is still possible if GPS fails. VORs provide lateral guidance but no vertical guidance, making them non-precision navigation aids.

Advancements in Navigation Technology

Modern technology solutions such as RNAV (Area Navigation) and GPS (Global Positioning System) offer considerable advantages over VORs. RNAV/GPS approaches are designed to be more precise and flexible, catering to a wider range of aircraft and runway conditions. These systems are also more reliable and can provide location accuracy in terrain-rich areas where VOR signals may be weak or unavailable.

ILS and Its Importance

For the most precise landings, especially in challenging conditions such as mountainous terrain, ILS (Instrument Landing System) is the most reliable option. ILS provides both lateral and vertical guidance, ensuring pilots can descend to lower approach minimums safely. However, not all airports have ILS, and reliance on VORs can sometimes be necessary for those relying on radio navigation equipment.

Future Trends in Air Navigation

Despite the usefulness of VORs, the future trend in airspace navigation appears to be moving towards a phase where VORs might become less common. Modern aircraft, equipped with RNAV capabilities or RNP (Required Navigation Performance) systems, can rely on GPS or other advanced navigation systems to fly precise approaches without the need for VORs. The latest systems, such as coupled GPS/INS (Inertial Navigation System) navigators and Flight Management Systems (FMS), work in tandem to provide comprehensive navigation and ensure safety in all conditions.

Best Practices for Pilots and Air Traffic Controllers

While RNAV/GPS and ILS are becoming more prevalent, having a co-located VOR with DME (Distance Measuring Equipment) at an airport can serve as a valuable backup, especially for pilots who may only rely on radio nav equipment. It's also essential for pilots to visually assess the terrain and weather conditions, as human eyes remain a crucial factor, particularly in areas with rugged topography.

In summary, while VORs have historical significance and are reliable in certain conditions, the modern trend favors RNAV/GPS and ILS for their precision and reliability. The key is for pilots and controllers to stay informed about the latest navigation systems and to use them effectively to ensure safe and efficient operations, particularly in complex terrain areas.