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Contents
PART 1
-
PART 11
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Challenges of
the Oceanic Airspace
-
The Future
-
Possible
Solutions for Mid and Long Term
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SIDs, STARs
and New Tracks in the Oceanic
Airspace
-
Radar
Linking
-
Restructuring
of Routes in the Oceanic
-
General
Improvements
-
Comments and
Conclusions
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Introduction
 I
wish to thank the organisers of
this seminar for giving me the
opportunity to address you on a
topic which is now gaining
greater and greater importance
as we seek to establish in our
areas of jurisdiction the facets
and principles for the various
components of the new CNS/ATM
systems for the future of
aviation, a discipline now
referred to as Air Traffic
Management.
Air Traffic Management, in
itself, incorporates many
aspects of the aviation
environment. Any general
discussion of ATM, will of
necessity include at least
concepts and topics such as
Airspace Management, Reduced
Vertical, Lateral, and
Longitudinal Separation, Air
Traffic Flow Management,
Conflict Prediction and Conflict
Alert, Standard Instrument
Departure Procedures, Standard
Arrival Routes etc. Such is the
diverse nature of the topic
itself.
The varied nature of the topic
has meant that if I am not to be
here for an hour or more, I
would have to select one of the
categories on which to make this
presentation.
As such I have
chosen to deal with Airspace
Planning within the area over
which Piarco has jurisdiction,
including the implications of RNAV and random Routes, and the
present impact on the airlines
which use the system, and the
providers who operate the
system. The airspace with which
I am familiar is the Piarco
Upper and Lower Control Area and
its Upper and Lower Flight
Information Region, hereinafter,
for ease of discussion, referred
to primarily as the CTA/FIR.
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In dealing with the subject
matter I have opted to use a
practical- approach, since, in
my opinion, all matters related
to the Air Traffic Services
result in the provision of an
operational service to the
airlines. In analyzing this
situation it will be important:
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1. Firstly to look briefly at
the present scenario of the
procedural environment, and the
route management challenges
related to the existing traffic
situation as it applies to the
present route structure.
(In this context, I will need to
explain briefly how the
Procedural environment works and
consider some of its inherent
limitations)
2. Secondly to look at the
possibilities for the future of
the sub region's airspace with a
brief discussion of workable
solutions which are consistent
with the ICAO route and area
navigation concepts.
(In this context, we look at the
user’s need for RNAV Routes, and
the providers’ capacities to
arrange an environment in which
there will be continuing safety
with a manageable workload for
air traffic controllers.)
The Present
The increase in traffic through
the Piarco FIR has brought with
it a number of challenges in the
local management and controller
management of the resulting air
traffic scenarios. Large numbers
of transatlantic aircraft via
established and RNAV routings
are either transiting the Piarco
CTA/FIR or operating into or out
of International Airports in the
Eastern Caribbean. Challenges in
the science of keeping aircraft
safely separated now exist due
to a number of inter-related
factors.
The
Procedural Environment
To understand why
this environment presents a
gnawing challenge to ATC, I will
need to provide a brief overview
at this point of the Procedural
ATC Environment and how it works
for the benefit of those who may
not be familiar with this type
of operation.
I suppose a simple way to define
a procedural environment is to
say that it is a non Radar
environment, and then argue that
every one here knows what is a
radar environment. But a more
precise definition would be that
a procedural air traffic control
environment is one in which
aircraft are separated by
utilizing pilot reports and
estimates for predetermined
points. These reporting points
are usually overhead navigation
beacons of various types, or
other significant positions
based on bearings and distance
from these beacons. Pilot
reports are then compared with
those calculated by the
controller and verified where
there are discrepancies, and
then used to project the
expected future positions of the
aircraft. This information is
then used to space aircraft
longitudinally, or depending on
whether, initially, there is
adequate longitudinal spacing,
to effect level changes.
Determination of Separation
in
the Procedural Mode.
In this type of
environment and within Piarco’s
control airspace, the
controller's tools for effecting
separation, are basically the
NDB, VOR and DME stations. These
navigational aids, when so
spaced are also used to
determine lateral separation
when there is no overlap of the
airspace to be protected. The
navaids are not necessarily
strategically placed, as may be
the situation within the USA,
but geographically and
conveniently placed owing to the
fact that the area is not a
large land mass but several
small islands. A controller sits
at a display board with
designators of the Reporting
Points arranged in such a manner
as to represent the chart of the
route structure and the area to
a trained eye. Flight Progress
strips for the aircraft which
form the current traffic
scenario, are placed
appropriately in time or level
sequence under these
designators.
The Controller takes and keeps a
mental picture of the traffic
situation, in three dimensions,
and projects the flight path of
the aircraft, based upon the
estimates provided, as
previously mentioned, in order
to determine whether separation
will exist in the future. He/she
then takes action accordingly to
ensure such future separation
along the route.
The
ECAR Route Structure
The design of a route
structure in a busy environment
should normally facilitate the
provision of separation,
particularly within the arrival
and departure phases of flight.
At present the ECAR Route
structure has slowly evolved to
be comprised basically, of
direct connections between
city/island pairs and at present
does not necessarily always
provide for automatic separation
between aircraft operating along
these routes. The controller
therefore has to be constantly
vigilant as to when such
separation between aircraft on
the same, converging and
crossing routes, will cease to
exist. This again is all based
upon estimates.
Among the ICAO standard methods
for dealing with separation
between routes based upon the
conventional navigation aids
are:-
1. The establishment of routes
from a VOR station so that their
angular divergence in the
arrival and departure phase,
meet the ICAO criteria set up
for separation. If this were
strictly adhered to, there would
be no routes emanating from a
VOR station that are closer than
15 degrees apart. However this
is not always practicable.
2. The Diamond Concept. This
concept also makes use of VOR
signals and is used for
relatively short distances,
where the route, in one
direction, forms a half of a
Diamond shape, and in the
opposite direction-- the other
half.
3. The RNP Concept. Within
recent times, as many of you
know, ICAO has established a new
concept which specifies the
minimum navigation performance
accuracy necessary for operation
within a defined airspace.
However, neither of the first
two concepts, was ever applied
within the airspace over which
Piarco has jurisdiction. We have
now begun to actively consider
the implications of the RNP
concept, and how it may be
applied within the area for
which we are responsible.
Today, I would like to point out
some of the existing challenges,
both for users and for us, with
the hope that there will be a
greater understanding of the
present system and its
constraints. This may be
particularly informative for
airline personnel who are more
familiar with a Radar
environment than with the
Procedural environment and its
challenges.
The
Challenges and implications of RNAV routes
in the procedural
system. (Controlled Airspace)
Allow me now the privilege of
talking briefly about random
routes and the present
implications for users and for
us within the CTA/UTA. In my
discourse, I will make generic
reference to random or RNAV
routes, for ease of discussion.
GNSS navigation, whether on
specific RNP or random routes,
allows operators to select the
most efficient flight paths for
their aircraft between departure
and destination points, allowing
for consequential savings in
fuel and time. Providing for
these preferred routes, is
acknowledged to be extremely
beneficial to the airline
industry, in order for users to
benefit from improved navigation
technology, and despite present
constraints, continues to be a
major objective of the ATS
providers.
We have found that in the past
and even, to some extent, at
present in the effort to provide
airlines with their requested
routes, controllers, have been
granting RNAV direct routes and
thereafter looking for methods
to provide the necessary
separations between aircraft for
level changes. Approvals to
preferred levels and ad-hoc
level changes have not always
been expeditious. Why not?
Separation of aircraft in the
procedural environment, is most
easily achieved when aircraft
involved are proceeding directly
to or away from the navigation
aid on which the separation is
predicated. However in many
cases of aircraft on random RNAV
or direct routes, the navaids
used to provide separation in
the climb or descent profile are
offset from the direct route,
and very often the separation is
difficult to achieve and
requires excessive
pilot/controller interchanges.
Procedural options for level
changes. (RNAV routes)
The relatively new RNAV
longitudinal separation criteria
in Document 4444 provides for a
basic 80 NMs separation between
RNAV equipped aircraft in
various circumstances. While
this has proven useful in
instances involving high level
movements, in many other
scenarios this separation may be
considered a bit exorbitant for
application at the medium levels
and lower airspeeds. In these
circumstances the options to
expedite the level changes may
then involve, in an RNAV
situation, the re-clearing of
one or both aircraft to proceed
initially towards the navaid
from which direct navigation
reference will then be possible,
with level restrictions to
ensure separation. Ensuring that
the level change is completed
outside of the required 15
miles, the separation is thus
accomplished.
RNAV
Separation Criteria?
The majority of developing
countries, has not been able to
develop detailed RNAV separation
criteria and are still dependent
upon the ICAO textbook type
standard, many of which are not
particularly compatible with the
justifiable expectations of most
cost-conscious airlines which,
of necessity are now equipping
their fleet with advanced
airborne navigation equipment.
Within the Piarco CTA, new
initiatives to be implemented,
relative to the application of
the ICAO Concept of Protected
Airspace, may allow for more
efficient management of the
airspace.
Increasing Traffic numbers and
the need for more direct
routings
The CNS/ATM concept has long
been accepted by many countries.
Improvements are planned where
global changes in route designs
are expected to cater for more
direct paths. These structural
route design changes are now
being established in many areas
of the world as users press for
and providers seek to afford the
facilities which will bring
early benefits to users who are
equipped with the new avionics
technology. This is not
extremely difficult within the
radar environment, as monitoring
and radar separation can apply
as may be necessary.
With the increasing numbers of
GNSS equipped aircraft within
the ECAR, ATS providers are
already seeing an increasing
number of requests for more
direct Trans-Atlantic and
TransCaribbean routes. The
traffic challenges are
compounded, as we couple the
factor of increased traffic
levels with the need to allow
for more direct routes. |
