TACAN Arcing

T-34C INSTRUMENTS

CHAPTER SIX

(b)

You will not necessarily be able to determine the exact heading to roll out

on as you are adjusting heading, but that is not as important as altering

your heading before it is too late. Once on your new heading, let things

settle down (e.g., cross a few radials; let a few tenths of DME pass) then

update again by trying to determine if you will hit the radial or DME

first. Remember your goal of getting as close as you can to the point.

Continually update until crossing the point.

In the event your solution does not work out exactly, you may arrive either at your

desired DME or radial prior to the fix. If arriving at the DME first and you are within

30 radials of the desired radial, turn to arc toward the fix. If arriving at the radial first,

turn to track inbound/outbound to the fix.

Common Errors

Failing to expedite the first six steps. Remember, there is plenty of time to refine your

solution once proceeding in the general direction.

Reversing the direction of the imaginary nowind heading line by extending the

imaginary line from the fix through the present position.

Failing to make frequent updates. As you get closer to the station more frequent

updates will be required to ensure an accurate solution.

Placing the wrong fix at the outer edge of the RMI card.

Proceeding to the reciprocal of the radial/DME instead of the radial/DME.

Attempting to arc to the fix when not within 30 radials of the desired fix.

Failing to make timely and accurate wind drift corrections enroute to the fix.

621.

TACAN ARCING

Reference: NIFM Part V, "TACAN Procedures."

Amplification Arcing is defined as flying at a constant distance from a TACAN or

VOR/DME station by reference to DME. Arcing around a station may be required to comply

with an ATC clearance and is an integral part of certain TACAN or VOR/DME approaches and

DPs. Arcing may also be employed as a corrective measure during pointtopoint maneuvers, if

you miss your destination point.

In practice, you do not actually fly a "perfect arc," but by varying AOB and heading, a close

approximation of an arc can be achieved.

RADIO INSTRUMENT FLIGHT PROCEDURES 6-57