TACAN is an acronym after Tactical Air Navigation system. It’s primary job is easing navigation by proving range and bearing to a known point (more info in the Wiki).
The TACAN station can be located anywhere, from an airfield to a Carrier, from a tanker to a fighter; with some specific differences depending on the host. Details about the AN/ARN-84 TACAN System installed on the F-14 are available in the manual).
TACAN switchology in the F-14
The F-14 has identical TACAN Control Panels for the RIO and the Pilot and its use is quite straightforward (see the manual for more detailed information):
- the channel is set by means of the two knobs (CHAN). The outer and the inner knobs control units and tens.
- the X/Y mode is set by its relative 2-way switch.
- the TACAN transceiver mode is controlled by the 5-position knob.
Albeit two TACAN Control Panels are installed (red), only one actually controls the TACAN. Which one is controlling it, is determined by means of the TACAN CMD button (green).
The usual operating mode is T/R (Transmit and Receive) and it can be set to A/A for Air-to-Air employment. REC (Receving mode) is a passive, non-emitting mode (it displays the bearing but not the range). BCN (Beacon) mode is not implemented.
A TACAN station is identified by a number and X or Y. Ground stations usually use X and airborne Y. For instance, to get bearing and distance to Kutaisi Airport, set 44X T/R. The TACAN for Carriers can be chanced in the mission editor; usually we use 76X (T/R) for the Stennis. A Tanker TACAN channel is again definable in the mission editor. For instance, it can be 39Y (A/A).
Note that T/R and A/A are not defined in the declaration of the TACAN channel, they are implied.
The Bearing, Distance, Heading Indicator is present in both cockpits and is a very useful means of monitoring the information coming from the TACAN, whilst having the HSD free for other tasks (for instance, navigating to a waypoint).
In the picture above, the range to the station is highlighted with the green box, the TACAN bearing needle with a red line.
Ground-based TACAN stations
In DCS, most of the military airfield located in NATO-“friendly” nations (or nations that have used this technology) have TACAN stations. For instance, the Georgian part of the Caucasus map, some airfields in Iran, Oman, Qatar and UAE in the Persian Gulf map and, of course, many airfields in the Nevada map, all have TACAN Stations (I haven’t checked the Normandy but being it a map set in WW2, it shouldn’t have any).
Ground based TACAN stations are very handy when it comes to RTB. They don’t suffer from INS drift and are instead a great means of fixing a “funny” INS. Therefore, the position of the airfield is usually very precise and reliable.
This is applicable to Carriers as well. In this situation the TACAN is extremely important because the CV is moving and there are no geographical reference points, unless you are operating near the coast.
Airborne TACAN stations
A TACAN transceiver can be installed on an aircraft to serve different purposes. One of the most common examples is the AAR (Air-to-Air Refueling).
The TACAN should be in A/A mode when operating with other airborne assets.
The purpose of the TACAN installed on Tankers is to allow an airplane low on fuel to quickly determine the position of the Tanker and join it for topping-up the tanks. The concept is not really different from the CV usage: determining the position of a moving station by means of distance and bearing from it.
The TACAN transceiver is commonly installed on any fairly modern (or upgraded), western aircraft. In DCS, this means almost any western module, such as F-14B, F/A-18C, F-16C, F-5E, A-10C and so on.
The TACAN mounted on such airplanes is able to both receive and transmit signals and can be used to provide a positional reference to both the leader and the wingman (Yardstick). On the other hand, the fighter-mounted TACAN cannot be used to determine the bearing to another fighter, only the range is provided.
The Yardstick is different from the other modes and it requires that the Leader and Wingmen channels are separated by 63.
If the settings are correct, the distance between the two aircraft is displayed on the HSD in TACAN mode and on the BDHI. In Yardstick mode, the TACAN needle will spin continuously, showing that the bearing cannot be determined.
Do not use channels used by other assets in the scenario, it can cause confusion and errors, especially in Yardstick mode.
Since the Pilot has harder time reaching for the TACAN panel whilst flying, his control panel can be set to Yardstick and the RIO can operate other channels. By means of the TACAN CMD button, the control can be quickly toggled between the two. Moreover, the TACAN CMD status is a quick reminder of what the TACAN is displaying: if it set to PLT (Pilot), then Yardstick is in use; otherwise, it depends on the settings in RIO’s panel. This makes the use of the TACAN much simpler and straightforward and avoid confusions. It works so well that we made it SOP in the 132nd VW, 108th vSquadron.
Since Yardstick and any other non-REC modes transmit data, for realism’s sake they should be turned off when FENCEing-IN or as described by SOP and briefing.