Tuning the AN/ARN-118 TACAN

BASIC INSTRUMENT PROCEDURES

CHAPTER ONE

CAUTION

During normal use of the baroset knob, if momentary locking of

the barocounters (the numbers in the Kollsman window) is

experienced, do not force the setting. Application of force may

cause internal gear disengagement and result in excessive altitude

errors in both primary and standby modes. If locking occurs,

rotate the baroset knob a full turn in the opposite direction and

approach the setting again with caution.

During instrument flight below 18,000 feet, the importance of obtaining the latest

altimeter setting cannot be overemphasized, particularly when flying from an area of

high pressure into a lower pressure area. "From high to low, look out below!"

Above 18,000 feet MSL the altimeter shall be set to 29.92 inches Hg. The current

local altimeter setting shall be set prior to descent through the lowest useable flight

level as defined in the current Flight Information Handbook. Use the RESET or

NORM modes of the altimeters at and above 18,000 feet MSL only.

Tactical Air Navigation (TACAN), Bearing-Distance-Heading-Indicator (BDHI), and

Course Indicator (ID-249).

General: The AN/ARN-118 TACAN, BDHI, and ID-249 will be used during Basic

Instrument and Emergency Procedures events only for orientation. Use of this

equipment during Radio Instrument and SUA events is covered in the RI Chapter.

The Tactical Air Navigation (TACAN) system was developed by the Navy to provide

aircrew with information needed for precise geographical fixing of the aircraft's

position at all times. Distance measuring equipment (DME), an integral part of the

TACAN system, provides continuous slant-range distance information. Like VOR,

TACAN provides 360 radials originating at the station. In addition, because TACAN

ground equipment is compact and relatively easy to transport, it provides for greater

versatility in site location and mobility than the VOR system, and can be placed in

remote locations and used on ships.

CHECK NOTAMS and FLIP before flight for possible malfunctions or limitations of

navigational aids to be used.

NOTE

If there is a malfunction of the compass system or card, consider

the TACAN azimuth information unreliable until verified by radar

or other navigational equipment.

Tuning the AN/ARN-118 TACAN.

BASIC INSTRUMENT PROCEDURES 1-11