CPDLC Route Uplink Options for Oceanic Clearances or Track Change
CPDLC Route Uplinks
 UM 79 CLEARED TO [position] VIA [route clearance]
 UM 80 CLEARED [route clearance]
 UM 83 AT [position] CLEARED [route clearance]
CPDLC Route Uplinks ATSU Concerns
 Routing to destination
 Route discontinuities
 Loss of Wx data (winds and temperature)
CPDLC Route Uplink Options (Flight on Original Flight Plan)
ELSIR
50N050W
50N040W
50N030W
50N020W
SOMAX
ATSUR
LND
Original Routing
--------- --------- --------- --------- --------- --------- --------- --------- ---------
UM 79 CLEARED TO LND VIA ELSIR 50N050W 50N040W 50N030W 50N020W SOMAX ATSUR
 Routing to destination
 No discontinuity
 Loss of Wx data on track only
UM 80 CLEARED ELSIR 50N050W 50N040W 50N030W 50N020W SOMAX ATSUR LND Original
Routing
 ATSU will have to “append” original routing
 No discontinuity
 Loss of all Wx data
CPDLC Route Uplink Options (Track Change)
Original
ELSIR
50N050W
50N040W
50N030W
50N020W
SOMAX
ATSUR
LND
Original Routing
--------- --------- --------- --------- --------- --------- --------- --------- ---------
New
JOOPY
49N050W
49N040W
49N030W
49N020W
BEDRA
NERTU
--------- --------- --------- --------- --------- --------- ---UM 79 CLEARED TO LND VIA JOOPY 49N050W 49N040W 49N030W 49N020W BEDRA NERTU
JOOPY
49N050W
49N040W
49N030W
49N020W
BEDRA
NERTU
LND
Original Routing
--------- --------- --------- --------- --------- --------- --------- --------- ---------
To avoid a route discontinuity, the uplink can be “anchored” to the first significant point after the
original track exit point; in this case LND.
 Routing to destination
 No discontinuity
 Loss of Wx data for track only
CPDLC Route Uplinks Pros and Cons
Pros
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Cons
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Replace ACARS 623 Oceanic Clearances
Eliminates flight crew “typing”
All Oceanic Clearances whether the original filed or a track change are loaded directly into
the FMS
Better ATC assurance that the FMS is loaded with the proper waypoints
UM 137 CONFIRM ASSIGNED ROUTE could be integrated into conformance monitoring and
provide immediate information as to whether the cleared route is loaded in the FMS.
ADS-C helps mitigate loss of some or all Wx data
ANSPs will need to develop procedures for “appending original routing” and the use of a
significant waypoint after track exit
Procedures would have to be implemented to allow route uplinks to be potentially sent from
a preceding ATSU
Loss of some or all Wx data
UM 137 CONFIRM ASSIGNED ROUTE can only be used with operators using full Lat/Long
ARINC 424 operators would receive uplink in a full Lat/Long format and would need to
understand the importance of waypoint verification procedures
Summary
The use of CPDLC route uplinks (specifically UM 79 in the event of a track change) can significantly
help in eliminating ALL track errors, half degree or whole. Issues on how to “construct” it and “when
and how” to send it need more discussion amongst the ANSPs. Any track change should include flight
crew and ATC procedures to verify routing after track exit. The loss of Wx data can easily be
mitigated by using information on the original flight plan or receipt from AOC via data link; ADS-C
could also help.
The expanded discussion below was offered in a WP presented by Gordon Sandell at CNSG/5. It was
used as a source document for the information provided above.
NORTH ATLANTIC COMMUNICATIONS, SURVEILLANCE AND
NAVIGATION GROUP
(NAT CNSG)
FIFTH MEETING
(Bodo, Norway, 26-30 September 2011)
Agenda Item 5:
Planning and implementation
b) Use of CPDLC for oceanic route re-clearances to destination without
discontinuities
Loading of Route Clearances
(Presented by United States of America)
Summary
This paper provides an overview of how route loading to the FMC occurs when
using the various uplink messages containing the [routeclearance] parameter.
1
INTRODUCTION
1.1
The NAT CNSG intends to provide recommendations to stakeholders, on which uplink
messages should be used to send route clearances to airplanes, so that they can be loaded
appropriately.
1.2
In order to be able to provide such a recommendation, it is necessary to understand how
such clearances are loaded by the airplane avionics systems, and how this may differ
between airplane and equipment manufacturers. The purpose of this paper is to provide
that guidance..
2
DISCUSSION
2.1
The FANS-1/A message set includes four uplink messages that contain the
[routeclearance] parameter. One of those is um73 (pre departure clearance), which is not
relevant to oceanic operation. There is also an uplink for EXPECT [routeclearance], but
that is not loadable. The loadable route clearance uplinks of interest are therefore:
Um79 CLEARED TO [position] VIA [routeclearance]
Um80 CLEARED [routeclearance]
Um83 AT [position] CLEARED [routeclearance]
2.2
Um79, when loaded into the Flight Management System, will replace the entire flight
plan, as far as the waypoint identified by the [position] parameter. This is shown in the
diagram below.
2.3
If the terminating fix (JKLMN in the example) does not exist in the active route, then the
resulting flight plan will consist of the uplinked route, the terminating fix, a flight plan
discontinuity, and then the entire existing flight plan. This is shown in the figure below.
2.4
Um80 will replace the entire flight plan route, as shown in the figure below.
2.5
Um83 is implemented differently by different airplane/equipment manufacturers. The
basic implementation is the same. The route is replaced after the specified position. This
is shown in the figure below.
2.6
In the case of Boeing airplanes, the entire route from that point on is replaced. On Airbus
airplanes, if the final fix in the route exists in the existing flight plan, then the route from
that point on is retained. These two different approaches are shown in the figure below.
2.7
If the specified [position] does not exist in the flight plan, then the entire uplinked route is
appended to the current route, with a flight plan discontinuity between them. This is
shown in the figure below.
2.8
Flight can discontinuities can also result when a fix or airway in the uplink cannot be
found in the airplane’s navigation database, or if the terminal area procedures do not
include appropriate transitions.
3
ACTION BY THE MEETING
3.1
The Group is invited to consider the information contained in this paper in determining
the best approach for uplinking route clearances.