TACAN Calibration Checks

BASIC INSTRUMENT PROCEDURES

CHAPTER ONE

Confirm that the:

DME OFF flag disappears.

ii.

TACAN needle points to 180.

iii.

CDI bar centers.

After 15 seconds, confirm that the:

DME indication.

ii.

TACAN needle.

iii.

Test light is extinguished.

iv.

Both return to "pretest indications."

If the test light comes on and remains on during, and/or after the completion of the

test, a malfunction is indicated.

Test Complete.

TACAN Calibration Checks. Ground checkpoints consist of a certified radial and DME

that should be received at a specific point on the airport surface. Taxiway signs located at hold

short areas usually designate these "checkpoints". Should an error in bearing exist in excess of

+ 4 or in DME of greater than 0.5 NM or 3% of the distance to the station, whichever is greater,

flight should not be attempted without first correcting the source of error. Errors observed which

are within the prescribed limits should be considered as applicable only to the radial and

transmitter checked, and as a check that the receiver is properly operating. Zero error should be

assumed when flying other radials and other TACAN stations, and no compensation made for

the observed error.

VORTAC. VORTAC is a combination VOR (Very-high-frequency Omnidirectional

Range) station and TACAN station, which operate simultaneously. A TACAN-

equipped aircraft receives azimuth and distance information from the TACAN

station, while the VOR/DME-equipped aircraft receives azimuth information from the

VOR station (Figure 1-2) and distance information from the TACAN station. The

two ground installations are usually housed in a single building and the coincident

position of the antennas establishes a common navigational fix for two navigation

systems. VORTAC is not an integration of the VOR and TACAN systems but rather

a coexistence of the two systems, which enables aircraft equipped with different types

of navigation receivers to navigate on the same airways.

BASIC INSTRUMENT PROCEDURES 1-13