Specifications

SECTION 9 - SUPPLEMENTS CESSNA
SUPPLEMENT 3 MODEL 172R NAV III
GFC 700 AFCS
U.S.
FAA APPROVED
NORMAL PROCEDURES (Continued)
ADF OPERATION NOTES: (Continued)
ELECTRICAL STORMS:
In the vicinity of electrical storms, an ADF indicator pointer tends to
swing from the station tuned toward the center of the storm.
NIGHT EFFECT:
This is a disturbance particularly strong just after sunset and just after
dawn. An ADF indicator pointer may swing erratically at these times. If
possible, tune to the most powerful station at the lowest frequency. If
this is not possible, take the average of pointer oscillations to determine
station bearing.
MOUNTAIN EFFECT:
Radio waves reflecting from the surface of mountains may cause the
pointer to fluctuate or show an erroneous bearing. This should be taken
into account when taking bearings over mountainous terrain.
COASTAL REFRACTION:
Radio waves may be refracted when passing from land to sea or when
moving parallel to the coastline. This also should be taken into account.
PERFORMANCE
There is no change in airplane performance when the Bendix/King KR
87 Automatic Direction Finder (ADF) is installed. However, the
installation of an externally mounted antenna or related external
antennas, will result in a minor reduction in cruise performance.
172RPHBUS-S3-00
S3-12