BY ORDER OF THE SECRETARY OF THE AIR FORCE AIR FORCE ...

AFMAN 11-217V1 3 JANUARY 2005 87
Chapter 6
NAVIGATION AIDS
6.1. Precautions. Various types of navigation aids are in use today, each serving a special
purpose. Although operating principles and cockpit displays will vary among navigation
systems, there are several precautionary actions that must be taken to prevent in-flight use of
erroneous navigation signals:
6.1.1. Identification. Check the identification of any navigation aid and monitor it
during flight IAW Chapter 7 of this manual.
6.1.2. Crosscheck Information. Use all suitable navigation equipment aboard the aircraft
and crosscheck heading and bearing information.
6.1.3. Estimated Time of Arrival. Never overfly an estimated time of arrival (ETA)
without a careful crosscheck of navigation aids and ground checkpoints.
6.1.4. Notices to Airmen. Check notices to airmen (NOTAM) and flight information
publication (FLIP) before flight for possible malfunctions or limitations to navigation
aids.
6.1.5. Suspect Navigation Aid. Discontinue use of any suspect navigation aid and, if
necessary, confirm aircraft position with radar (ground or airborne) or other equipment.
Advise ATC of any problems receiving NAVAIDs--the problem may be the ground
station and not your aircraft's equipment.
6.2. VHF Omni-Directional Range (VOR).
6.2.1. VOR Frequency. VORs operate within the 108.0 to 117.95 MHz, or very high
frequency (VHF) and have a power output necessary to provide coverage within their
assigned operational service volume. The equipment is subject to line-of-sight
restriction, and its range varies proportionally to the altitude of the receiving equipment.
6.2.2. Voice Transmission. Most VORs are equipped for voice transmission. VORs
without voice capability are indicated on enroute and sectional charts by underlining the
VOR frequency or by the designation "VORW" in the IFR Supplement. Since a large
portion of the frequencies available on the VOR control panel may overlap the VHF
communication frequency band, you may use the VOR receiver as a VHF
communications receiver.
6.2.3. Accuracy. The accuracy of course alignment of the VOR is excellent, being
generally plus or minus 1°, but no more than 2.5°.
6.2.4. Identification. The only positive method of identifying a VOR is by its Morse
code identification (either aural or alphanumeric display that meets the requirements of
chapter 7) or by the recorded automatic voice identification. Voice identification consists
of a voice announcement, "COUSHATTA VOR," alternating with the usual Morse code
identification. During periods of maintenance, the facility may radiate a T-E-S-T code or
the code may be removed.