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emergency climb has been made, your altitude,
amount of flight time remaining (fuel state),
and number of persons on board. You should
then request a vector to either VFR weather
conditions or to the nearest suitable airport/heliport that conditions will support a successful
approach. If unable to contact ATC and a
transponder code has not been previously
established with ATC for inadvertent IMC,
change the transponder code to 7700.
3
A radio altimeter is a necessity for alerting the pilot when inadvertently going below the minimum altitude. Barometric altimeters are subject to inaccuracies that become important in helicopter IFR operations, especially in cold temperatures. (See Appendix B.)
7-18
IFR HELIPORTS
Advisory Circular 150/5390-2, Heliport Design, provides recommendations for heliport design to support
non-precision, approach with vertical guidance (APV),
and precision approaches to a heliport. When a heliport
does not meet the criteria of this AC, FAA Order
8260.42, Helicopter Global Positioning System (GPS)
Nonprecision Approach Criteria, requires that an
instrument approach be published as a SPECIAL
procedure with annotations that special aircrew qualifications are required to fly the procedure. Currently
there are no operational civil IFR heliports in the U.S.
although the U.S. military has some nonprecision and
precision approach procedures to IFR heliports.
A-1
EVOLUTION OF AIRBORNE
NAVIGATION DATABASES
There are nearly as many different area navigation
(RNAV) platforms operating in the National Airspace
System (NAS) as there are aircraft types. The range of
systems and their capabilities is
greater now than at any other time
in aviation history. From the simplest panel-mounted LOng RAnge
Navigation (LORAN), to the moving-map display global positioning
system (GPS) currently popular for
general aviation aircraft, to the
fully integrated flight management
system (FMS) installed in corporate and commercial aircraft, the
one common essential element is
the database. [Figure A-1]
RNAV systems must not only be
capable of determining an aircraft’s position over the surface of
the earth, but they also must be
able to determine the location of
other fixes in order to navigate.
These systems rely on airborne
navigation databases to provide
detailed information about these
fixed points in the airspace or on
the earth’s surface. Although, the
location of these points is the primary concern for navigation, these
databases can also provide many
other useful pieces of information
about a given location.
HISTORY
In 1973, National Airlines installed the Collins ANS70 and AINS-70 RNAV systems in their DC-10 fleet;
this marked the first commercial use of avionics that
required navigation databases. A short time later, Delta
Air Lines implemented the use of an ARMA
Corporation RNAV system that also used a navigation
database. Although the type of data stored in the two systems was basically identical, the designers created the
databases to solve the individual problems of each sys-
tem. In other words, the data was not interchangeable.
This was not a problem because so few of the systems were in use, but as the implementation of
RNAV systems expanded, a world standard for airborne navigation databases had to be created.
In 1973, Aeronautical Radio, Inc. (ARINC) sponsored
the formation of a committee to standardize aeronautical databases. In 1975, this committee published the
first standard (ARINC Specification 424), which has
remained the worldwide-accepted format for coding
airborne navigation databases.
There are many different types of RNAV systems certified for instrument flight rules (IFR) use in the NAS.
The two most prevalent types are GPS and the multisensor FMS.
Figure A-1. Area Navigation Receivers.
A-2
Most GPSs operate as stand-alone RNAV systems. A
modern GPS unit accurately provides the pilot with the
aircraft’s present position; however, it must use an airborne navigation database to determine its direction or
distance from another location unless a latitude and
longitude for that location is manually entered. The
database provides the GPS with position information
for navigation fixes so it may perform the required geodetic calculations to determine the appropriate tracks,
headings, and distances to be flown.
Modern FMSs are capable of a large number of functions including basic en route navigation, complex
departure and arrival navigation, fuel planning, and
precise vertical navigation. Unlike stand-alone navigation systems, most FMSs use several navigation inputs.
　
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