Chapter 8. Medical Facts for Pilots
Section 1. Fitness for Flight
8-1-1. Fitness For Flight 8-1-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-1-2. Effects of Altitude 8-1-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-1-3. Hyperventilation in Flight 8-1-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-1-4. Carbon Monoxide Poisoning in Flight 8-1-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-1-5. Illusions in Flight 8-1-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-1-6. Vision in Flight 8-1-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-1-7. Aerobatic Flight 8-1-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-1-8. Judgment Aspects of Collision Avoidance 8-1-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 9. Aeronautical Charts and
Related Publications
Section 1. Types of Charts Available
9-1-1. General 9-1-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9-1-2. Obtaining Aeronautical Charts 9-1-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9-1-3. Selected Charts and Products Available 9-1-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9-1-4. General Description of each Chart Series 9-1-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9-1-5. Where and How to Get Charts of Foreign Areas 9-1-12 . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 10. Helicopter Operations
Section 1. Helicopter IFR Operations
10-1-1. Helicopter Flight Control Systems 10-1-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10-1-2. Helicopter Instrument Approaches 10-1-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10-1-3. Helicopter Approach Procedures to VFR Heliports 10-1-5 . . . . . . . . . . . . . . . . . . . . . .
10-1-4. The Gulf of Mexico Grid System 10-1-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Section 2. Special Operations
10-2-1. Offshore Helicopter Operations 10-2-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10-2-2. Helicopter Night VFR Operations 10-2-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10-2-3. Landing Zone Safety 10-2-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10-2-4. Emergency Medical Service (EMS) Multiple Helicopter Operations 10-2-16 . . . . . . . .
Appendices
Appendix 1. Bird/Other Wildlife Strike Report Appendix 1-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix 2. Volcanic Activity Reporting Form (VAR) Appendix 2-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix 3. Laser Beam Exposure Questionnaire Appendix 3-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix 4. Abbreviations/Acronyms Appendix 4-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pilot/Controller Glossary PCG-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Index I-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3/15/07 7110.65R CHG 2 AIM 7/31/08
AIM 2/14/08
1-1-1
Navigation Aids
Chapter 1. Air Navigation
Section 1. Navigation Aids
1-1-1. General
a. Various types of air navigation aids are in use
today, each serving a special purpose. These aids have
varied owners and operators, namely: the Federal
Aviation Administration (FAA), the military ser-
vices, private organizations, individual states and
foreign governments. The FAA has the statutory
authority to establish, operate, maintain air naviga-
tion facilities and to prescribe standards for the
operation of any of these aids which are used for
instrument flight in federally controlled airspace.
These aids are tabulated in the Airport/Facility
Directory (A/FD).
b. Pilots should be aware of the possibility of
momentary erroneous indications on cockpit displays
when the primary signal generator for a groundbased navigational transmitter (for example, a
glideslope, VOR, or nondirectional beacon) is
inoperative. Pilots should disregard any navigation
indication, regardless of its apparent validity, if the
particular transmitter was identified by NOTAM or
otherwise as unusable or inoperative.
1-1-2. Nondirectional Radio Beacon (NDB)
a. A low or medium frequency radio beacon
transmits nondirectional signals whereby the pilot of
an aircraft properly equipped can determine bearings
and “home” on the station. These facilities normally
operate in a frequency band of 190 to 535 kilohertz
(kHz), according to ICAO Annex 10 the frequency
range for NDBs is between 190 and 1750 kHz, and
transmit a continuous carrier with either 400 or
1020_hertz (Hz) modulation. All radio beacons
except the compass locators transmit a continuous
three-letter identification in code except during voice
transmissions.
b. When a radio beacon is used in conjunction with
the Instrument Landing System markers, it is called
a Compass Locator.
c. Voice transmissions are made on radio beacons
unless the letter “W” (without voice) is included in
the class designator (HW).
d. Radio beacons are subject to disturbances that
may result in erroneous bearing information. Such
disturbances result from such factors as lightning,
precipitation static, etc. At night, radio beacons are
vulnerable to interference from distant stations.
Nearly all disturbances which affect the Automatic
Direction Finder (ADF) bearing also affect the
facility's identification. Noisy identification usually
occurs when the ADF needle is erratic. Voice, music
or erroneous identification may be heard when a
steady false bearing is being displayed. Since ADF
receivers do not have a “flag” to warn the pilot when
erroneous bearing information is being displayed, the
pilot should continuously monitor the NDB's
identification.
1-1-3. VHF Omni-directional Range (VOR)
a. VORs operate within the 108.0 to 117.95 MHz
frequency band and have a power output necessary to
provide coverage within their assigned operational
service volume. They are subject to line-of-sight
restrictions, and the range varies proportionally to the
altitude of the receiving equipment.
NOTE-
Normal service ranges for the various classes of VORs are
given in Navigational Aid (NAVAID) Service Volumes,
paragraph 1-1-8.
b. Most VORs are equipped for voice transmis-
sion on the VOR frequency. VORs without voice
capability are indicated by the letter “W” (without
voice) included in the class designator (VORW).
c. The only positive method of identifying a VOR
is by its Morse Code identification or by the recorded
automatic voice identification which is always
indicated by use of the word “VOR” following the
range's name. Reliance on determining the identifica-
tion of an omnirange should never be placed on
listening to voice transmissions by the Flight Service
Station (FSS) (or approach control facility) involved.
Many FSSs remotely operate several omniranges
with different names. In some cases, none of the
VORs have the name of the “parent” FSS. During
AIM 2/14/08
1-1-2 Navigation Aids
periods of maintenance, the facility may radiate a
T-E-S-T code (-_______-) or the code may be
removed.
d. Voice identification has been added to numer-
ous VORs. The transmission consists of a voice
announcement, “AIRVILLE VOR” alternating with
the usual Morse Code identification.
e. The effectiveness of the VOR depends upon
proper use and adjustment of both ground and
airborne equipment.
1. Accuracy. The accuracy of course align-
ment of the VOR is excellent, being generally plus or
minus 1 degree.
2. Roughness. On some VORs, minor course
roughness may be observed, evidenced by course
needle or brief flag alarm activity (some receivers are
more susceptible to these irregularities than others).
At a few stations, usually in mountainous terrain, the
pilot may occasionally observe a brief course needle
oscillation, similar to the indication of “approaching
station.” Pilots flying over unfamiliar routes are
cautioned to be on the alert for these vagaries, and in
particular, to use the “to/from” indicator to determine
positive station passage.
(a) Certain propeller revolutions per minute
(RPM) settings or helicopter rotor speeds can cause
the VOR Course Deviation Indicator to fluctuate as
much as plus or minus six degrees. Slight changes to
the RPM setting will normally smooth out this
roughness. Pilots are urged to check for this
modulation phenomenon prior to reporting a VOR
station or aircraft equipment for unsatisfactory
operation.
1-1-4. VOR Receiver Check
a. The FAA VOR test facility (VOT) transmits a
test signal which provides users a convenient means
to determine the operational status and accuracy of a
VOR receiver while on the ground where a VOT is
located. The airborne use of VOT is permitted;
however, its use is strictly limited to those
areas/altitudes specifically authorized in the A/FD or
appropriate supplement.
b. To use the VOT service, tune in the VOT
frequency on your VOR receiver. With the Course
Deviation Indicator (CDI) centered, the omnibearing selector should read 0 degrees with the
to/from indication showing “from” or the omnibearing selector should read 180 degrees with the
to/from indication showing “to.” Should the VOR
receiver operate an RMI (Radio Magnetic Indicator),
it will indicate 180 degrees on any omni-bearing
selector (OBS) setting. Two means of identification
are used. One is a series of dots and the other is a
continuous tone. Information concerning an individ-
ual test signal can be obtained from the local FSS.
c. Periodic VOR receiver calibration is most
important. If a receiver's Automatic Gain Control or
modulation circuit deteriorates, it is possible for it to
display acceptable accuracy and sensitivity close into
the VOR or VOT and display out-of-tolerance
readings when located at greater distances where
weaker signal areas exist. The likelihood of this
deterioration varies between receivers, and is
generally considered a function of time. The best
assurance of having an accurate receiver is periodic
calibration. Yearly intervals are recommended at
which time an authorized repair facility should
recalibrate the receiver to the manufacturer's
specifications.
d. Federal Aviation Regulations (14 CFR
Section_91.171) provides for certain VOR equipment
accuracy checks prior to flight under instrument
flight rules. To comply with this requirement and to
ensure satisfactory operation of the airborne system,
the FAA has provided pilots with the following means
of checking VOR receiver accuracy:
1. VOT or a radiated test signal from an
appropriately rated radio repair station.
2. Certified airborne check points.
3. Certified check points on the airport surface.
e. A radiated VOT from an appropriately rated
radio repair station serves the same purpose as an
FAA VOR signal and the check is made in much the
same manner as a VOT with the following
differences:
1. The frequency normally approved by the
Federal Communications Commission is
108.0_MHz.
2. Repair stations are not permitted to radiate the
VOR test signal continuously; consequently, the
owner or operator must make arrangements with the
repair station to have the test signal transmitted. This
service is not provided by all radio repair stations.
The aircraft owner or operator must determine which
AIM 2/14/08
1-1-3
Navigation Aids
repair station in the local area provides this service.
A representative of the repair station must make an
entry into the aircraft logbook or other permanent
record certifying to the radial accuracy and the date
of transmission. The owner, operator or representa-
tive of the repair station may accomplish the
necessary checks in the aircraft and make a logbook
entry stating the results. It is necessary to verify
which test radial is being transmitted and whether you
should get a “to” or “from” indication.
f. Airborne and ground check points consist of
certified radials that should be received at specific
points on the airport surface or over specific
landmarks while airborne in the immediate vicinity of
the airport.
1. Should an error in excess of plus or minus
4_degrees be indicated through use of a ground check,
or plus or minus 6 degrees using the airborne check,
Instrument Flight Rules (IFR) flight shall not be
attempted without first correcting the source of the
error.
CAUTION-
No correction other than the correction card figures
supplied by the manufacturer should be applied in
making these VOR receiver checks.
2. Locations of airborne check points, ground
check points and VOTs are published in the A/FD and
are depicted on the A/G voice communications
panels on the FAA IFR area chart and IFR enroute low
altitude chart.
3. If a dual system VOR (units independent of
each other except for the antenna) is installed in the
aircraft, one system may be checked against the other.
Turn both systems to the same VOR ground facility
and note the indicated bearing to that station. The
maximum permissible variations between the two
indicated bearings is 4 degrees.
1-1-5. Tactical Air Navigation (TACAN)
a. For reasons peculiar to military or naval
operations (unusual siting conditions, the pitching
and rolling of a naval vessel, etc.) the civil
VOR/Distance Measuring Equipment (DME) system
of air navigation was considered unsuitable for
military or naval use. A new navigational system,
TACAN, was therefore developed by the military and
naval forces to more readily lend itself to military and
naval requirements. As a result, the FAA has
integrated TACAN facilities with the civil VOR/
DME program. Although the theoretical, or technical
principles of operation of TACAN equipment are
quite different from those of VOR/DME facilities, the
end result, as far as the navigating pilot is concerned,
is the same. These integrated facilities are called
VORTACs.
b. TACAN ground equipment consists of either a
fixed or mobile transmitting unit. The airborne unit in
conjunction with the ground unit reduces the
transmitted signal to a visual presentation of both
azimuth and distance information. TACAN is a pulse
system and operates in the Ultrahigh Frequency
(UHF) band of frequencies. Its use requires TACAN
airborne equipment and does not operate through
conventional VOR equipment.
1-1-6. VHF Omni-directional
Range/Tactical Air Navigation (VORTAC)
a. A VORTAC is a facility consisting of two
components, VOR and TACAN, which provides
three individual services: VOR azimuth, TACAN
azimuth and TACAN distance (DME) at one site.
Although consisting of more than one component,
incorporating more than one operating frequency,
and using more than one antenna system, a VORTAC
is considered to be a unified navigational aid. Both
components of a VORTAC are envisioned as
operating simultaneously and providing the three
services at all times.
b. Transmitted signals of VOR and TACAN are
each identified by three-letter code transmission and
are interlocked so that pilots using VOR azimuth with
TACAN distance can be assured that both signals
being received are definitely from the same ground
station. The frequency channels of the VOR and the
TACAN at each VORTAC facility are “paired” in
accordance with a national plan to simplify airborne
operation.
1-1-7. Distance Measuring Equipment
(DME)
a. In the operation of DME, paired pulses at a
specific spacing are sent out from the aircraft (this is
the interrogation) and are received at the ground
station. The ground station (transponder) then
transmits paired pulses back to the aircraft at the same
pulse spacing but on a different frequency. The time
required for the round trip of this signal exchange is
AIM 2/14/08
1-1-4 Navigation Aids
measured in the airborne DME unit and is translated
into distance (nautical miles) from the aircraft to the
ground station.
b. Operating on the line-of-sight principle, DME
furnishes distance information with a very high
degree of accuracy. Reliable signals may be received
at distances up to 199 NM at line-of-sight altitude
with an accuracy of better than 1
/2 mile or 3 percent
of the distance, whichever is greater. Distance
information received from DME equipment is
SLANT RANGE distance and not actual horizontal
distance.
c. Operating frequency range of a DME according
to ICAO Annex 10 is from 960 MHz to 1215 MHz.
Aircraft equipped with TACAN equipment will
receive distance information from a VORTAC
automatically, while aircraft equipped with VOR
must have a separate DME airborne unit.
d. VOR/DME, VORTAC, Instrument Landing
System (ILS)/DME, and localizer (LOC)/DME
navigation facilities established by the FAA provide
course and distance information from collocated
components under a frequency pairing plan. Aircraft
receiving equipment which provides for automatic
DME selection assures reception of azimuth and
distance information from a common source when
designated VOR/DME, VORTAC, ILS/DME, and
LOC/DME are selected.
e. Due to the limited number of available
frequencies, assignment of paired frequencies is
required for certain military noncollocated VOR and
TACAN facilities which serve the same area but
which may be separated by distances up to a few
miles.
f. VOR/DME, VORTAC, ILS/DME, and LOC/
DME facilities are identified by synchronized
identifications which are transmitted on a time share
basis. The VOR or localizer portion of the facility is
identified by a coded tone modulated at 1020 Hz or
a combination of code and voice. The TACAN or
DME is identified by a coded tone modulated at
1350_Hz. The DME or TACAN coded identification
is transmitted one time for each three or four times
that the VOR or localizer coded identification is
transmitted. When either the VOR or the DME is
inoperative, it is important to recognize which
identifier is retained for the operative facility. A
single coded identification with a repetition interval
of approximately 30 seconds indicates that the DME
is operative.
g. Aircraft equipment which provides for
automatic DME selection assures reception of
azimuth and distance information from a common
source when designated VOR/DME, VORTAC and
ILS/DME navigation facilities are selected. Pilots are
cautioned to disregard any distance displays from
automatically selected DME equipment when VOR
or ILS facilities, which do not have the DME feature
installed, are being used for position determination.
1-1-8. Navigational Aid (NAVAID) Service
Volumes
a. Most air navigation radio aids which provide
positive course guidance have a designated standard
service volume (SSV). The SSV defines the reception
limits of unrestricted NAVAIDs which are usable for
random/unpublished route navigation.
b. A NAVAID will be classified as restricted if it
does not conform to flight inspection signal strength
and course quality standards throughout the
published SSV. However, the NAVAID should not be
considered usable at altitudes below that which could
be flown while operating under random route IFR
conditions (14_CFR Section 91.177), even though
these altitudes may lie within the designated SSV.
Service volume restrictions are first published in
Notices to Airmen (NOTAMs) and then with the
alphabetical listing of the NAVAIDs in the A/FD.
c. Standard Service Volume limitations do not
apply to published IFR routes or procedures.
d. VOR/DME/TACAN Standard Service
Volumes (SSV).
1. Standard service volumes (SSVs) are graphi-
cally shown in FIG 1-1-1, FIG 1-1-2, FIG 1-1-3,
FIG 1-1-4, and FIG 1-1-5. The SSV of a station is
indicated by using the class designator as a prefix to
the station type designation.
EXAMPLE-
TVOR, LDME, and HVORTAC.
AIM 2/14/08
1-1-5
Navigation Aids
FIG 1-1-1
Standard High Altitude Service Volume
(See FIG 1-1-5 for altitudes below 1,000 feet).
60,000 ft.
100 NM
130 NM
45,000 ft.
18,000 ft.
14,500 ft.
1,000 ft. 40 NM
FIG 1-1-2
Standard Low Altitude Service Volume
(See FIG 1-1-5 for altitudes below 1,000 feet).
NOTE: All elevations shown are with respect
to the station's site elevation (AGL).
Coverage is not available in a cone of
airspace directly above the facility.
40 NM
18,000 ft.
1,000 ft.
FIG 1-1-3
Standard Terminal Service Volume
(See FIG 1-1-4 for altitudes below 1,000 feet).
25 NM
12,000 ft.
1,000 ft.
AIM 2/14/08
1-1-6 Navigation Aids
2. Within 25 NM, the bottom of the T service
volume is defined by the curve in FIG 1-1-4. Within
40 NM, the bottoms of the L and H service volumes
are defined by the curve in FIG 1-1-5. (See
TBL 1-1-1.)
e. Nondirectional Radio Beacon (NDB)
1. NDBs are classified according to their
intended use.
2. The ranges of NDB service volumes are
shown in TBL 1-1-2. The distances (radius) are the
same at all altitudes.
TBL 1-1-1
VOR/DME/TACAN Standard Service Volumes
SSV Class Designator Altitude and Range Boundaries
T (Terminal) . . . . . . . . From 1,000 feet above ground level (AGL) up to and including 12,000 feet AGL at radial distances out
to 25 NM.
L (Low Altitude) . . . . From 1,000 feet AGL up to and including 18,000 feet AGL at radial distances out to 40 NM.
H (High Altitude) . . . . From 1,000 feet AGL up to and including 14,500 feet AGL at radial distances out to 40 NM. From
14,500_AGL up to and including 60,000 feet at radial distances out to 100 NM. From 18,000 feet AGL
up to and including 45,000 feet AGL at radial distances out to 130 NM.
TBL 1-1-2
NDB Service Volumes
Class Distance (Radius)
Compass Locator 15 NM
MH 25 NM
H 50 NM*
HH 75 NM
*Service ranges of individual facilities may be less than 50 nautical miles (NM). Restrictions to service
volumes are first published as a Notice to Airmen and then with the alphabetical listing of the NAVAID in
the A/FD.
FIG 1-1-4
Service Volume Lower Edge Terminal
1000
500
0
0 5 10 15 20 25
DISTANCE TO THE STATION IN NM
ALTITUDE IN FEET
AIM 2/14/08
1-1-7
Navigation Aids
FIG 1-1-5
Service Volume Lower Edge
Standard High and Low
1000
500
0
0 10 20 30 40
DISTANCE TO THE STATION IN NM
ALTITUDE IN FEET
5 15 25 35
1-1-9. Instrument Landing System (ILS)
a. General
1. The ILS is designed to provide an approach
path for exact alignment and descent of an aircraft on
final approach to a runway.
2. The ground equipment consists of two highly
directional transmitting systems and, along the
approach, three (or fewer) marker beacons. The
directional transmitters are known as the localizer
and glide slope transmitters.
3. The system may be divided functionally into
three parts:
(a) Guidance information: localizer, glide
slope;
(b) Range information: marker beacon,
DME; and
(c) Visual information: approach lights,
touchdown and centerline lights, runway lights.
4. Precision radar, or compass locators located
at the Outer Marker (OM) or Middle Marker (MM),
may be substituted for marker beacons. DME, when
specified in the procedure, may be substituted for the
OM.
5. Where a complete ILS system is installed on
each end of a runway; (i.e., the approach end of
Runway 4 and the approach end of Runway 22) the
ILS systems are not in service simultaneously.
b. Localizer
1. The localizer transmitter operates on one of
40 ILS channels within the frequency range of
108.10_to 111.95 MHz. Signals provide the pilot with
course guidance to the runway centerline.
2. The approach course of the localizer is called
the front course and is used with other functional
parts, e.g., glide slope, marker beacons, etc. The
localizer signal is transmitted at the far end of the
runway. It is adjusted for a course width of (full scale
fly-left to a full scale fly-right) of 700 feet at the
runway threshold.
3. The course line along the extended centerline
of a runway, in the opposite direction to the front
course is called the back course.
CAUTION-
Unless the aircraft's ILS equipment includes reverse
sensing capability, when flying inbound on the back
course it is necessary to steer the aircraft in the direction
opposite the needle deflection when making corrections
from off-course to on-course. This “flying away from the
needle” is also required when flying outbound on the
front course of the localizer. Do not use back course
signals for approach unless a back course approach
procedure is published for that particular runway and the
approach is authorized by ATC.
AIM 2/14/08
1-1-8 Navigation Aids
4. Identification is in International Morse Code
and consists of a three-letter identifier preceded by
the letter I ( _ _) transmitted on the localizer
frequency.
EXAMPLE-
I-DIA
5. The localizer provides course guidance
throughout the descent path to the runway threshold
from a distance of 18 NM from the antenna between
an altitude of 1,000 feet above the highest terrain
along the course line and 4,500 feet above the
elevation of the antenna site. Proper off-course
indications are provided throughout the following
angular areas of the operational service volume:
(a) To 10 degrees either side of the course
along a radius of 18 NM from the antenna; and
(b) From 10 to 35 degrees either side of the
course along a radius of 10 NM. (See FIG 1-1-6.)
FIG 1-1-6
Limits of Localizer Coverage
RUNWAY
LOCALIZER
ANTENNA
10 NM
18 NM
LIMITS OF LOCALIZER
COVERAGE: THE SAME APPLIES TO A BACK NORMAL AREA
COURSE
WHEN PROVIDED.
10
10
35
35
6. Unreliable signals may be received outside
these areas.
c. Localizer Type Directional Aid (LDA)
1. The LDA is of comparable use and accuracy
to a localizer but is not part of a complete ILS. The
LDA course usually provides a more precise
approach course than the similar Simplified
Directional Facility (SDF) installation, which may
have a course width of 6 or 12 degrees.
2. The LDA is not aligned with the runway.
Straight-in minimums may be published where
alignment does not exceed 30 degrees between the
course and runway. Circling minimums only are
published where this alignment exceeds 30 degrees.
3. A very limited number of LDA approaches
also incorporate a glideslope. These are annotated in
the plan view of the instrument approach chart with
a note, “LDA/Glideslope.” These procedures fall
under a newly defined category of approaches called
Approach with Vertical Guidance (APV) described in
paragraph 5-4-5, Instrument Approach Procedure
Charts, subparagraph a7(b), Approach with Vertical
Guidance (APV). LDA minima for with and without
glideslope is provided and annotated on the minima
lines of the approach chart as S-LDA/GS and
S-LDA. Because the final approach course is not
aligned with the runway centerline, additional
maneuvering will be required compared to an ILS
approach.
d. Glide Slope/Glide Path
1. The UHF glide slope transmitter, operating
on one of the 40 ILS channels within the frequency
range 329.15 MHz, to 335.00 MHz radiates its signals
in the direction of the localizer front course. The term
“glide path” means that portion of the glide slope that
intersects the localizer.
CAUTION-
False glide slope signals may exist in the area of the
localizer back course approach which can cause the glide
slope flag alarm to disappear and present unreliable glide
slope information. Disregard all glide slope signal
indications when making a localizer back course
approach unless a glide slope is specified on the approach
and landing chart.
2. The glide slope transmitter is located between
750 feet and 1,250 feet from the approach end of the
runway (down the runway) and offset 250 to 650 feet
from the runway centerline. It transmits a glide path
beam 1.4 degrees wide (vertically). The signal
provides descent information for navigation down to
the lowest authorized decision height (DH) specified
in the approved ILS approach procedure. The
glidepath may not be suitable for navigation below
the lowest authorized DH and any reference to
glidepath indications below that height must be
supplemented by visual reference to the runway
environment. Glidepaths with no published DH are
usable to runway threshold.
3. The glide path projection angle is normally
adjusted to 3 degrees above horizontal so that it
intersects the MM at about 200 feet and the OM at
AIM 2/14/08
1-1-9
Navigation Aids
about 1,400 feet above the runway elevation. The
glide slope is normally usable to the distance of
10_NM. However, at some locations, the glide slope
has been certified for an extended service volume
which exceeds 10 NM.
4. Pilots must be alert when approaching the
glidepath interception. False courses and reverse
sensing will occur at angles considerably greater than
the published path.
5. Make every effort to remain on the indicated
glide path.
CAUTION-
Avoid flying below the glide path to assure
obstacle/terrain clearance is maintained.
6. The published glide slope threshold crossing
height (TCH) DOES NOT represent the height of the
actual glide path on-course indication above the
runway threshold. It is used as a reference for
planning purposes which represents the height above
the runway threshold that an aircraft's glide slope
antenna should be, if that aircraft remains on a
trajectory formed by the four-mile-to-middle
marker glidepath segment.
