Volume 4 AIRCRAFT EQUIPMENT AND OPERATIONAL AUTHORIZATION
Chapter 1 AIR NAVIGATION, COMMUNICATIONS, AND SURVEILLANCE
Section 3 Class I Navigation
4-51 GENERAL. This section provides concepts,
direction, and guidance that should be used by FAA inspectors when evaluating
and approving or denying requests for authorization to conduct Class I navigation
operations not previously approved for a particular operator. This includes
proposed Class I navigation operations using aircraft and/or navigation systems
new to that operator, as well as Class I navigation operations into areas of
en route operation new to that operator using previously approved aircraft and
navigation systems. This section amplifies the general concepts, policies, and
guidance provided in section 1 of this chapter. Specific “standard practices”
are provided in this section for evaluating Class I navigation operations using
navigation systems that, within particular areas of en route operations, understand
operational characteristics and limitations. When an operator requests approval
to conduct Class I navigation using a means of navigation not addressed by these
standard practices, a request for direction and guidance must be forwarded through
Regional Flight Standards Division to the Air Transportation Division (AFS-200).
4-52 VFR CLASS I NAVIGATION. Visual flight rules
(VFR) Class I navigation is any Class I navigation operation conducted under
VFR in visual meteorological conditions (VMC). The primary objectives of VFR
Class I navigation are as follows:
· Arrive at the intended destination with sufficient fuel remaining to safely
complete a landing
· Operate with sufficient visual references to reliably “see and avoid” all obstacles
along the actual routes of flight
· Operate with sufficient visibility to safely “see and avoid” all other aircraft
· Navigate with sufficient precision to avoid special area of operation areas
and positive air traffic control (ATC) areas or to comply with the special requirements
of those areas
· Protect persons and property on the ground, which is an important factor in
route selection and route approval, especially for those aircraft that have
inadequate performance capability with an engine inoperative
A. Safe Separation of Aircraft Under VFR. Since
the safe separation of aircraft under VFR is provided by “see and avoid” procedures,
an inspector must ensure that the flight conditions (ceiling and visibility)
specified for an operation reliably permit application of this concept. In most
cases, basic VFR weather minima (part
91.155) are sufficient for the “see and avoid” concept. However, the requirements
to arrive at the intended destination, avoid obstacles along the actual route
of flight, and adequately protect persons and property on the ground are more
complex. In general, basic VFR weather minima are adequate to safely accomplish
these objectives in uncongested areas that have numerous prominent landmarks
and benign terrain/obstacle characteristics. However, operations in other areas
generally require a case-by-case evaluation and may require flight conditions
that require better seeing-conditions than that provided by basic VFR weather
minima. In determining the degree of accuracy required for VFR operations, the
inspector must consider the minimum flight conditions (ceiling and visibility)
required for safe operations.
B. Conduct of VFR Flight. In the conduct of
VFR flight, the prevention of collisions (safe separation from other aircraft)
is solely the responsibility of the pilot-in-command (PIC) to see and avoid.
However, there are regulatory requirements for use of navigation systems such
as VOR for VFR operations in oceanic or desolated land areas or for night VFR
and VFR over the top operations. These regulatory requirements are related to
locating the intended destination, avoiding obstacles along the actual route
of flight, and the protection of persons and property on the ground.
4-53 TYPES OF VFR CLASS I NAVIGATION. These
are two types of VFR Class I navigation. They are referred to as “pilotage”
A. Pilotage. One of the primary means of conducting
VFR Class I navigation is by pilotage. Pilotage is defined in Title 14 of the
Code of Federal Regulations (14 CFR) part 1 as “navigation by visual reference
1) Pilotage is an appropriate means of navigation
only in those areas and/or situations where the flight conditions (ceiling and
visibility) are sufficient to consistently identify prominent landmarks and
to “see and avoid” obstacles and other aircraft. Examples of prominent landmarks
include villages, rivers, roads, valleys, ridges, transmission lines, and in
some cases, lighted objects at night.
2) Pilotage is not an appropriate
means of VFR Class I navigation in areas or situations where prominent landmarks
or lighted objects do not exist or where these visual references are widely
separated. For example, desolate areas without prominent and permanent features,
such as deserts, the Tar Pits in Canada, huge forests, certain Arctic areas,
or large bodies of water (such as parts of the Great Lakes and the Gulf of Mexico),
are areas where pilotage is not an appropriate means of navigation.
B. Station-Referenced. In situations
where pilotage is not appropriate, it is necessary to use other means of conducting
VFR Class I navigation to locate the intended destination, avoid obstacles,
and protect persons and property on the ground. This is accomplished by using
electronic station-referenced (nonvisual) navigational aids (NAVAID), such as
VOR, DME, NDB, or LORAN-C, and GNSS.
1) Conventional ground-based NAVAIDs
(VOR, DME, NDB) can be used to fly published routes. In this case, obstacle
avoidance is provided if the operation is conducted at or above the published
minimum en route IFR altitude minimum en route altitude
(MEA) or (if appropriate) the minimum obstruction clearance altitude
2) Area navigation systems can
be used to conduct VFR Class I navigation. Most area navigation systems are
station-referenced systems; however, an inertial navigation system (INS) is
self-contained and the Global Navigation Satellite System (GNSS) is space based.
Although these systems are referenced to specific navigation stations (VOR,
VOR/DME, and LORAN-C), area navigation systems permit point-to-point navigation
and are not limited to routes from one ground station to the next. Since the
VFR navigation performance requirements are not as demanding as IFR requirements,
operators can use area navigation systems for VFR that are not certificated
for IFR en route operations. However, certain systems, such as LORAN-C and GPS,
must be certified as airworthy for VFR and installed in accordance with approved
4-54 VFR CLASS I NAVIGATION APPROVALS. General
direction and guidance on air navigation approvals is provided in section 2.
A. Determining Degree of Accuracy. In
determining the degree of accuracy required for pilotage and station-referenced
VFR Class I navigation, an inspector must consider the minimum flight conditions
necessary for safe operations. If it is determined that flight conditions better
than basic VFR weather minima are required for safe operations, the specific
flight conditions (e.g., ceiling visibility) must be specified in the operations
specifications (OpSpecs) for the pertinent area or route. When making this determination
for station referenced Class I navigation, consideration should be given to
the additional accuracy provided by the electronic navigation equipment. In
addition, station referenced navigation requires that the navigational equipment
used is airworthy for VFR operations within the proposed area of operation and
installed in accordance with approved data. The operator must provide written
evidence of the airworthiness approval for the required equipment. When a minimum
flight condition for either pilotage or station referenced Class I navigation
is specified in OpSpecs, it must provide for the following criteria:
· Meets regulatory requirements for the operation
· Meets the standard practices in this handbook
· Meets the requirements of part B of the OpSpecs
· Provides accepted, safe operating practice
· Permits “see and avoid”
· Permits the identification and avoidance of obstacles
· Ensures adequate protection of persons and property on the ground
· Permits reliable identification of prominent landmarks or lighted objects at
· Permits reliable navigation to the intended destination
B. Pilotage and Station-Referenced Approvals.
Pilotage and station-referenced approvals are granted by issuance or amendments
to OpSpecs. The areas of operation authorized for pilotage or station-referenced
Class I VFR navigation, along with any required minimum flight condition, must
be specified in the OpSpecs.
C. Area Navigation Systems.
· INS/Inertial Reference System (IRS)
INSTRUMENT FLIGHT RULES (IFR) CLASS I NAVIGATION.
A. IFR Class I navigation is any Class I navigation
operation conducted under IFR. The following are the primary objectives of IFR
Class I navigation:
· Navigating with sufficient precision to permit ATC to safely separate IFR aircraft.
· Arriving at the intended destination with adequate fuel remaining to safely
complete a landing.
· Avoiding all obstacles along the actual route of flight.
· Providing adequate protection for persons and property on the ground, especially
for those aircraft with inadequate performance capability with an inoperative
· Meeting the requirements of part B of OpSpecs.
B. Safe Separation of Aircraft. Since the safe
separation of aircraft under IFR in controlled airspace is dependent on the
aircraft’s navigational performance, an inspector must determine that the navigational
equipment and the navigation procedures and techniques used by the operator
ensure that the operation will be conducted with the precision necessary to
meet the objectives listed in the previous subparagraph. Inspectors must consider
the following when approving IFR Class I navigation:
· Situations when the means of navigation is other than VOR or VOR/DME will normally
require a case-by-case evaluation.
· In all cases, the means of navigation must enable navigation to the degree of
accuracy required for the control of air traffic.
· IFR Class I navigation is only conducted within the operational service Volume
of standard International Civil Aviation Organization (ICAO) NAVAIDs.
4-56 TYPES OF IFR CLASS I NAVIGATION. There
are two generic types of IFR Class I navigation:
· Navigation by direct reference to ICAO standard NAVAIDs
· Navigation by use of RNAV systems.
A. ICAO Standard NAVAIDs. The primary means
of conducting IFR Class I navigation has historically been station-referenced
to ICAO standard ground-based NAVAIDs (VOR, VOR/DME, NDB). The route structure
and the ATC separation standards in most countries are based on the use of these
ground-based NAVAIDs. When operating within the operational service volumes
of these ground-based NAVAIDs, these standard systems may be used to satisfy
the objectives of IFR Class I navigation. However, with the implementation of
GPS, ICAO now includes GPS as an additional standard NAVAID. Two subtypes of
IFR Class I navigation can be conducted using ICAO standard NAVAIDs: ground-based
or space-based. These subtypes are navigation on published IFR routes and point-to-point
1) Within the United States and Canada, standard
NAVAIDs may be used to conduct Class I navigation when flying any published
IFR route or procedure, provided these operations are conducted at or above
the published minimum IFR altitudes. The following are examples of published
· Victor airways
· Colored airways
· Jet/high level routes
· Standard Instrument Departures (SID)
· Standard Terminal Arrivals (STAR)
· Instrument departures.
NOTE: This also includes those cases where the route
is published with a “gap” in signal coverage.
2) In many foreign countries and in oceanic/remote
areas, the situation is more complex. The determination of whether Class I navigation
is appropriate must be based on ICAO standards or their equivalence to U.S.
standards. In general, most published VOR and VOR/ DME routes (airways) are
equivalent to U.S. standards and IFR Class I navigation can be conducted over
these routes using standard VOR, VOR/DME equipment. In many areas outside the
United States and Canada, some of the published routes are based on NDBs. Any
published route must be evaluated to determine whether the route involves Class
I or Class II navigation, or both. For example, if the entire portion of a route
based on NDB is determined to be Class I navigation, NDB equipment is usually
sufficient to conduct airway navigation over that route when flying at or above
the specified minimum IFR altitude. Point-to-point IFR Class I navigation based
on NDBs generally requires a case-by-case evaluation to ensure the operation
will be conducted in accordance with ICAO or U.S. standards. The fact that the
route is approved by the ICAO contracting State does not automatically mean
that the route meets these safety criteria.
3) IFR Class I navigation can be conducted over
unpublished point to point routes (off airways), provided all of the following
conditions are met:
· Positive course guidance is available from standard ICAO NAVAIDs.
· The routes are within the operational service Volume of these NAVAIDs.
· The operation is conducted at or above the IFR minimum altitude published or
approved for that route by the ICAO contracting state having jurisdiction over
· The required airborne, ground-based and/or space-based navigational facilities
are available and operational to enable navigation to the degree of accuracy
required for the control of air traffic.
B. Area Navigation Systems. Appropriate area navigation
systems can be used to conduct IFR Class I navigation. Any area navigation system
used for IFR flight must provide present position information and navigation
guidance to maintain the assigned track and arrive at the designated waypoints.
Area navigation may be based on the following:
· VOR and DME-source-referenced
· LORAN-C, GNSS earth-referenced in accordance with WGS84 or equivalent
· Self-contained in the aircraft (INS, IRS).
1) IFR Class I navigation can be conducted with
IFR-approved area navigation systems suitable for the area of operations. Area
navigation systems must be evaluated to ensure that the system and the operator
are capable of navigating to the degree of accuracy required for control of
air traffic within the proposed area of operation
2) In U.S. Class A airspace (18,000 feet mean
sea level (MSL) to Flight Level (FL) 600), IFR Class I navigation can be conducted
with suitable area navigation systems that are not approved for IFR flight in
areas where domestic ATS procedures are applied. In the U.S. Class A airspace,
additional safety is provided by ATC radar. This independent surveillance method
and the procedures specified for this type of operation provides an equivalent
level of safety and permits safe separation of aircraft. RNAV operations can
be authorized provided the following conditions are met:
· The flightcrew is properly trained for the equipment and special procedures
to be used.
· Each flight operation is authorized by the appropriate ATC facility.
· The entire portion of the intended route of flight using the area navigation
system will be in the U.S. Class A airspace and under positive radar control.
· Contingency procedures are established so that the flight can immediately return
to and use airways facilities at any point in the flight.
· The airborne navigational equipment (VOR, DME, ADF) required to navigate in
Class A airspace is installed and operational.
4-57 IFR CLASS I NAVIGATION APPROVALS. General
direction and guidance of air navigation approvals are in section 2. Specific
direction and guidance for approving IFR Class I navigation is discussed in
the following subparagraphs.
A. Degree of Accuracy Required. Inspectors must determine
that the navigational equipment and the operational procedures/techniques used
permit reliable IFR Class I navigation to the degree of accuracy required for
the control of air traffic. The degree of accuracy required for any IFR Class
I navigation operation must provide for the following criteria:
· Meets regulatory requirements for IFR airways navigation
· Meets the standard practices in this order
· Meets the requirements of part B of the OpSpecs
· Provides accepted, safe operating practices
· Permits the safe separation of aircraft
· Ensures obstacle avoidance along the route of flight
· Ensures adequate protection for persons and property on the ground
· Permits reliable navigation to the intended destination and any necessary alternate
or diversionary airports
B. Airworthiness of Navigational Equipment. Inspectors
must determine that required navigational equipment is certified for IFR flight
and installed in accordance with approved data. The operator must provide written
evidence of the airworthiness approval for the required equipment. The operator
must also provide written evidence that shows that any RNAV system used for
IFR Class I navigation meets the performance criteria for the proposed area
of operation. If, for example, the proposed area of operation includes areas
of magnetic unreliability (AMU), the navigation equipment must be approved for
IFR operations in that environment.
C. Other Factors. Inspectors must determine that the
operator's manuals, training programs, minimum equipment lists (MELs), and company
policies and practices adequately address the proposed IFR Class I navigation
operation and the equipment to be used considering the following factors:
· Terrain characteristics
· The operator’s experience with other aircraft and navigation systems in the
area of proposed operation
· The operator’s experience with the same aircraft and navigation in similar areas
· The need to adequately protect persons or property on the ground
· Operations in special areas of operation, including AMU
· Use of special means of navigation
· Use of special navigation techniques
D. Approval. IFR Class I navigation approvals are granted
by issuance of or amendments to OpSpecs. The areas of operation authorized must
be specified in part B, paragraph B050 of OpSpecs (see Volume 3, Chapter 18.)
NOTE: The inspector will not, under any circumstances,
issue OpSpecs approving IFR Class I navigation operations until all requirements
are met (including the principal avionics inspector’s (PAI) approval of the
operator’s programs, if required) and the operator is capable of commencing
RESERVED. Paragraphs 4-58 through 4-75.