What is VORTAC

A VORTAC is a co-located ground facility that combines two different types of radio navigation aids: a VOR (VHF Omnidirectional Range) and a TACAN (Tactical Air Navigation). From a single location, this station provides three distinct navigation services, catering to the different equipment found in military and civilian aircraft.

Think of it as a single power outlet with both a standard USB port and a USB-C port, allowing different devices to draw power from the same source. VORTAC is the universal adapter for the skies.

How VORTAC Works

The genius of VORTAC lies in its ability to transmit multiple signals from one site, each serving a specific user.

For the Civilian (VOR + DME):
When a pilot in a commercial airliner or a general aviation aircraft tunes a VORTAC frequency, their navigation equipment interprets it as two separate components:

1. The VOR Component: The aircraft’s VOR receiver locks onto the VOR signal, which provides magnetic bearing information. This tells the pilot which of the 360 “radials” from the station they are located on.
2. The DME Component: The aircraft’s Distance Measuring Equipment (DME) interrogates the TACAN portion of the station. The TACAN transponder replies, and the aircraft’s DME calculates the precise slant-range distance in nautical miles.

To the civilian pilot, the VORTAC behaves exactly like a VOR/DME station. They get both direction and distance from one tuned frequency, all without knowing the military-grade TACAN technology is working behind the scenes to provide the distance data.

For the Military (TACAN):
A military aircraft equipped with a TACAN set simply tunes to the same VORTAC channel. Its integrated system receives both bearing and distance information directly from the TACAN transponder. The TACAN-bearing signal is inherently more accurate than a standard VOR, giving military pilots the high precision they require for tactical operations.

In this elegant arrangement, both users access the services they need from a single, shared point on the ground, maximizing infrastructure efficiency while serving diverse needs.

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VORTAC in Action

For a pilot, using a VORTAC is seamless. The process is identical to using any other navigation aid:

1. Tuning and Identifying: The pilot tunes the VORTAC’s frequency (e.g., 113.5 MHz) into their navigation radio and listens for the station’s Morse code identifier (e.g., “BOS” for a Boston VORTAC) to confirm they have the correct facility.
2. Course Selection: Using the Omni Bearing Selector (OBS) on a traditional CDI or the flight management system in a glass cockpit, the pilot selects the desired radial to or from the station.
3. Navigation: The cockpit instruments display the aircraft’s position relative to the selected course and show the distance to the station. The pilot can then track to or from the VORTAC, use it to define a holding pattern, or simply use it as a fixed point to determine their precise location on a chart.

VORTAC vs VOR/DME vs TACAN

Feature	VORTAC	VOR/DME	TACAN
Primary Users	Civilian & Military	Civilian	Military
Bearing Source	VOR Transmitter	VOR Transmitter	TACAN Transmitter
Bearing Accuracy	Standard VOR (~1-2°)	Standard VOR (~1-2°)	High-Accuracy TACAN (~0.25°)
Distance Source	TACAN Transponder	DME Transponder	TACAN Transponder
Physical Station	Two co-located units	Two co-located units	Single, compact unit

The key takeaway is that a VORTAC is essentially a VOR/DME station that uses TACAN technology to provide the DME function, thereby making its services available to military users as well.

The Strategic Role of VORTAC in the GPS Era

With the dominance of satellite-based GPS, one might assume ground-based systems like VORTAC are obsolete. The reality is quite the opposite. VORTAC has taken on a new, critically important role as a pillar of navigation resilience.

• Backup to GPS: The signals from GPS satellites are incredibly weak and vulnerable to both intentional jamming and unintentional interference. VORTAC provides a powerful, terrestrial, and independent source of navigation that is immune to these space-based disruptions.
• Updating Inertial Systems: Modern aircraft use Inertial Navigation Systems (INS), but these systems accumulate small errors over time. By taking a “fix” from a VORTAC, the aircraft’s navigation computer can update and correct the inertial system, ensuring long-term accuracy even without GPS.
• The Minimum Operational Network (MON): Recognizing the need for a backup, the FAA has established a MON of VORTACs across the United States. While some redundant stations have been decommissioned, this carefully maintained network ensures that pilots can always navigate and land safely anywhere in the country, even during a widespread GPS outage.

The Future of VORTAC

The future of VORTAC is not about expansion but about guaranteed availability. Its role has shifted from a primary navigational tool to a strategic reserve. As aviation progresses towards more complex and automated systems, the value of a simple, reliable, and independent ground-based navigation aid only increases.

VORTAC stations will continue to be maintained and modernized, not for everyday use, but for the critical day when they are needed most. They are the safety net that allows the aviation industry to embrace the incredible benefits of GPS with the confidence that there is always a proven, resilient backup.

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VORTAC FAQs

1. As a civilian pilot, how do I know if a station is a VORTAC?
On aeronautical charts, a VORTAC is symbolized by a hexagon with a small dot in the center. The frequency and identifier are published just like any other VOR. In the cockpit, you use it exactly as you would a VOR/DME.

2. Can a civilian aircraft use the TACAN bearing from a VORTAC?
Generally, no. Standard civilian VOR receivers are designed to interpret the VOR signal, not the TACAN bearing signal. The high-precision TACAN bearing remains a military-specific feature.

3. What’s the difference between a VORTAC and a VOR?
A VOR only provides bearing (direction). A VORTAC provides both bearing and distance. All VORTACs provide distance, but not all VORs do (some are VOR-only, without a co-located DME or TACAN).

4. Are there any VORTACs on aircraft carriers?
Yes! This is a key application. Aircraft carriers are equipped with TACAN stations. When a carrier’s TACAN is used for navigation, it is referred to as a TCN on aeronautical charts, but it provides the same bearing and distance service to military aircraft as a land-based TACAN.

5. How long will VORTACs remain in service?
Indefinitely. While the number of stations has been reduced to a Minimum Operational Network (MON), there are no plans to completely eliminate them. Their value as a resilient backup to GPS ensures their place in the national airspace system for the foreseeable future.