| Home | Privacy | Contact |

Pilot's Handbook of Aeronautical Knowledge

Radio Navigation

| First | Previous | Next | Last |

Pilot's Handbook of Aeronautical Knowledge



Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making




While maintaining a heading of 360°, assume that the course
deviation begins to move to the left. This means that the wind
correction of 10° is too great and the aircraft is flying to the
right of course. A slight turn to the left should be made to
permit the aircraft to return to the desired radial.

When the deviation needle centers, a small wind drift
correction of 5° or a heading correction of 355° should be
flown. If this correction is adequate, the aircraft remains
on the radial. If not, small variations in heading should be
made to keep the needle centered, and consequently keep the
aircraft on the radial.

As the VOR station is passed, the course deviation needle
fluctuates, then settles down, and the "TO" indication
changes to "FROM." If the aircraft passes to one side of the
station, the needle deflects in the direction of the station as
the indicator changes to "FROM."

Generally, the same techniques apply when tracking
outbound as those used for tracking inbound. If the intent is
to fly over the station and track outbound on the reciprocal of
the inbound radial, the course selector should not be changed.
Corrections are made in the same manner to keep the needle
centered. The only difference is that the omnidirectional
range indicator indicates "FROM."

If tracking outbound on a course other than the reciprocal of
the inbound radial, this new course or radial must be set in
the course selector and a turn made to intercept this course.
After this course is reached, tracking procedures are the same
as previously discussed.

Tips on Using the VOR
• Positively identify the station by its code or voice
• Keep in mind that VOR signals are "line-of-sight." A
weak signal or no signal at all is received if the aircraft
is too low or too far from the station.
• When navigating to a station, determine the inbound
radial and use this radial. Fly a heading that will
maintain the course. If the aircraft drifts, fly a heading
to re-intercept the course then apply a correction to
compensate for wind drift.
• If minor needle fluctuations occur, avoid changing
headings immediately. Wait momentarily to see if the
needle recenters; if it does not, then correct.
• When flying "TO" a station, always fly the selected
course with a "TO" indication. When flying "FROM" a
station, always fly the selected course with a "FROM"
indication. If this is not done, the action of the course
deviation needle is reversed. To further explain this
reverse action, if the aircraft is flown toward a station
with a "FROM" indication or away from a station
with a "TO" indication, the course deviation needle
indicates in an direction opposite to that which it
should indicate. For example, if the aircraft drifts to
the right of a radial being flown, the needle moves to
the right or points away from the radial. If the aircraft
drifts to the left of the radial being flown, the needle
moves left or in the direction opposite to the radial.

• When navigating using the VOR it is important to .y
headings that maintain or re-intercept the course. Just
turning toward the needle will cause overshooting
the radial and flying an S turn to the left and right of

Time and Distance Check From a Station
To compute time and distance from a station, first turn the
aircraft to place the bearing pointer on the nearest 90° index.
Note time and maintain heading. When the bearing pointer
has moved 10°, note the elapsed time in seconds and apply
the formulas in the following example to determine time and
distance. [Figure 15-33]

Time-distance check example.
Figure 15-33. Time-distance check example.

The time from station may also be calculated by using a short
method based on the above formula, if a 10° bearing change
is flown. If the elapsed time for the bearing change is noted
in seconds and a 10° bearing change is made, the time from
the station in minutes is determined by counting off one
decimal point. Thus, if 75 seconds are required to fly a 10°
bearing change, the aircraft is 7.5 minutes from the station.
When the bearing pointer is moving rapidly or when several
corrections are required to place the pointer on the wingtip
position, the aircraft is at station passage.

The distance from the station is computed by multiplying TAS
or GS (in miles per minute) by the previously determined time
in minutes. For example, if the aircraft is 7.5 minutes from
station, flying at a TAS of 120 knots or 2 NM per minute, the
distance from station is 15 NM (7.5 x 2 = 15).