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AIM

10/12/17

1−1−18

Navigation Aids

(b) GPS receivers used for VFR navigation

vary from fully integrated IFR/VFR installation used

to support VFR operations to hand−held devices.

Pilots must understand the limitations of the receivers

prior to using in flight to avoid misusing navigation

information. (See TBL 1−1−6.) Most receivers are

not intuitive. The pilot must learn the various

keystrokes, knob functions, and displays that are

used in the operation of the receiver. Some

manufacturers provide computer−based tutorials or

simulations of their receivers that pilots can use to

become familiar with operating the equipment.

(c) When using GPS for VFR operations,

RAIM capability, database currency, and antenna

location are critical areas of concern.

(1) RAIM Capability. VFR GPS panel

mount receivers and hand−held units have no RAIM

alerting capability. This prevents the pilot from being

alerted to the loss of the required number of satellites

in view, or the detection of a position error. Pilots

should use a systematic cross−check with other

navigation techniques to verify position. Be

suspicious of the GPS position if a disagreement

exists between the two positions.

(2) Database Currency. Check the curren-

cy of the database.  Databases must be updated for

IFR operations and should be updated for all other

operations. However, there is no requirement for

databases to be updated for VFR navigation. It is not

recommended to use a moving map with an outdated

database in and around critical airspace. Pilots using

an outdated database should verify waypoints using

current aeronautical products; for example, Chart

Supplement U.S., Sectional Chart, or En Route

Chart.

(3) Antenna Location. The antenna loca-

tion for GPS receivers used for IFR and VFR

operations may differ. VFR antennae are typically

placed for convenience more than performance,

while IFR installations ensure a clear view is

provided with the satellites. Antennae not providing

a clear view have a greater opportunity to lose the

satellite navigational signal. This is especially true

in the case of hand−held GPS receivers. Typically,

suction cups are used to place the GPS antennas on

the inside of cockpit windows. While this method has

great utility, the antenna location is limited to the

cockpit or cabin which rarely provides a clear view

of all available satellites.  Consequently, signal losses

may occur due to aircraft structure blocking satellite

signals, causing a loss of navigation capability. These

losses, coupled with a lack of RAIM capability, could

present erroneous position and navigation informa-

tion with no warning to the pilot. While the use of a

hand−held GPS for VFR operations is not limited by

regulation, modification of the aircraft, such as

installing a panel− or yoke−mounted holder, is

governed by 14 CFR Part 43. Consult with your

mechanic to ensure compliance with the regulation

and safe installation.

(d) Do not solely rely on GPS for VFR

navigation. No design standard of accuracy or

integrity is used for a VFR GPS receiver. VFR GPS

receivers should be used in conjunction with other

forms of navigation during VFR operations to ensure

a correct route of flight is maintained. Minimize

head−down time in the aircraft by being familiar with

your GPS receiver’s operation and by keeping eyes

outside scanning for traffic, terrain, and obstacles.

(e) VFR Waypoints

(1) VFR waypoints provide VFR pilots

with a supplementary tool to assist with position

awareness while navigating visually in aircraft

equipped with area navigation receivers. VFR

waypoints should be used as a tool to supplement

current navigation procedures. The uses of VFR

waypoints include providing navigational aids for

pilots unfamiliar with an area, waypoint definition of

existing reporting points, enhanced navigation in and

around Class B and Class C airspace, and enhanced

navigation around Special Use Airspace. VFR pilots

should rely on appropriate and current aeronautical

charts published specifically for visual navigation.  If

operating in a terminal area, pilots should take

advantage of the Terminal Area Chart available for

that area, if published. The use of VFR waypoints

does not relieve the pilot of any responsibility to

comply with the operational requirements of 14 CFR

Part 91.

(2) VFR waypoint names (for computer−

entry and flight plans) consist of five letters

beginning with the letters “VP” and are retrievable

from navigation databases. The VFR waypoint

names are not intended to be pronounceable, and they

are not for use in ATC communications. On VFR

charts, stand−alone VFR waypoints will be portrayed

using the same four−point star symbol used for IFR

waypoints. VFR waypoints collocated with visual

check points on the chart will be identified by small