B.5.9
WP95
Review Continuous
Descent Operations
Manual
Presented by:
Bill Holtzman (USA)
Roosevelt Pena (Dom Rep)
on behalf of TOC
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CDO WP95
FAA Administrator
Note: This video from February 8, 2011 was shown at the
Amman Conference but is not available for distribution.
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Current Operations
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Continuous Descent
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IATA
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Doc 9931
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Doc 9931 Definition
Continuous Descent Operations (CDO)
is an aircraft operating technique aided
by appropriate airspace and procedure
design and appropriate air traffic control
(ATC) clearances enabling the execution
of a flight profile optimized to the
operating capability of the aircraft, with
low engine thrust settings and, where
possible, a low drag configuration,
thereby reducing fuel burn and
emissions during descent.
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Terminology
• “Continuous Descent Operations”
(CDO) is a class of procedures.
• “Continuous Descent Approach”
(CDA) is a procedure.
• “Optimized Profile Descent” (OPD) is
a procedure. This term is used in the
USA.
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CDAs in the UK
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Los Angeles Intl (LAX)
• First published OPD in the US, the
River One STAR - 2007
• Average savings - 25 gallons a flight
for 300-400 daily
• Fifth busiest US airport with 545,000
operations in 2009
• 40+% of LAX approaches now OPDs
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RIIVR2
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RIIVR2 Profile
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RIIVR2 to ILS
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The LA Way
1.
2.
3.
4.
Use active controllers
Obtain data on typical trajectories
Apply the “90%” rule
Build an initial CDA
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The LA Way
5.
6.
7.
8.
9.
Break trajectory into segments
Use a trajectory simulation tool
Redesign the associated sectors
Perform simulation testing
Begin implementation
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US Lessons Learned
Critical elements
• Precisely spaced arrival flow
• Automated wind information
• “90% rule”
• Design to hit merge points
• Lots of simulation
Not necessary
• Dynamic resectorization
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Doc 9931 - Predictability
Manual identifies two goals:
• Continuous descent
• Increased flight predictability
To the controller, predictability is:
• Restricted trajectory - single 3D path
• “Low tolerance” CDA
To the pilot:
• Unrestricted trajectory
• “High tolerance” CDA
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Trajectories
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90% Envelope
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Open Path
1.2.1.5.2 - The open path design is a
design where a portion, or all, of the
route consists of vectoring. The specific
distance to runway threshold is not
known prior to start of the CDA.
Two procedures:
• Vectored CDA
• Open CDA to Downwind
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Open CDA to Downwind
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Closed Path
1.2.1.5.1.1 - The closed path design is
a design where the route is fixed and
the specific distance to the runway is
known prior to start of the continuous
descent operation. The procedure may
be published with crossing levels, level
windows and/or speed constraints. The
design of the closed path may comprise
the STAR and (initial) approach phases
of flight until the FAF/FAP final approach
point (FAP).
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Path Stretching
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Merge Points
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Tailored Arrivals (TA)
• On demand, individually constructed
route and profile clearance
• Transmitted via data link from
Ocean21 system to FANS-1/A aircraft
• 6 years of testing in Australia,
Netherlands and US
• Operational in San Francisco, Los
Angeles, Miami this year
• Fuel savings – 75-400 gallons per
arrival (280-1500 L)
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Conclusions
1. The CDO Manual incorrectly uses the term
“CDO” to refer to a procedure.
2. The ICAO definition of CDO only considers
the perspective of a single aircraft.
3. Flight predictability should be increased for
both the aircraft and the ATM system.
4. Best practices for CDA design should be
derived from successful implementations.
5. Open Path CDAs are a compromise between
predictability and controller flexibility.
6. Restricting the controller’s ability to
intervene reduces ATM capacity.
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Conclusions
7. In CDA design, there is a trade-off between
capacity and the aircraft’s optimal flight
path.
• “Low tolerance” CDA
 Higher predictability for controller
 Higher capacity for non-arrival traffic
 Inhibits ideal engine-idle trajectories
• “High tolerance” CDA
 Lower predictability for controller
 Lower capacity for non-arrival traffic
 Pilots fly ideal descent trajectories
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Debate
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Recommendations
4.1 - IFATCA Policy is:
IFATCA defines Continuous Descent
Operations as:
Continuous Descent Operations (CDO) are
aircraft operating techniques facilitated by
appropriate airspace and procedure design
which meet all ATM requirements, allowing
the execution of an optimized descent
profile.
and is included in the IFATCA Technical and
Professional Manual.
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Recommendations
4.2 – IFATCA Policy is:
IFATCA supports the development and
implementation of Continuous Descent
Operations provided that:
Controllers are involved in the design.
Airspace is suited to the design.
The design meets the desired ATM capacity.
Tactical ATC interventions are allowed.
Flight predictability is increased for both pilots
and controllers.
• Controller workload is not increased beyond an
acceptable level.
•
•
•
•
•
and is included in the IFATCA Technical and
Professional Manual.
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Recommendations
4.3 - IFATCA Policy is:
Doc 9931 should be amended as follows:
• Incorporate CDA design practices learned by
the pioneers of continuous descent,
including the 90% rule, the use of extensive
simulation and the need for automated wind
data and advanced sequencing tools.
• More precisely refer to those procedures it
aims to regulate as either Continuous
Descent Arrivals (CDAs) or Optimized Profile
Descents (OPDs).
and is included in the IFATCA Technical and
Professional Manual.