Oceanic
ITP
Airborne Traffic Situational Awareness
– In-Trail Procedure (ATSA-ITP)
Presented to the ASAS Thematic Network 2
Malmo, Sweden
September 27, 2005
Stephane Marche
Ken Jones
Tom Graff
Outline
ATSA - ITP
 Background
– Oceanic Challenges
– TCAS In-Trail Climb/Descent
 Airborne Traffic Situational Awareness – In-Trail
Procedure
– Overview
– Chronology of RFG activities
 Summary
2
North Atlantic Organized Track System
Overview and Technical Challenges
ATSA - ITP
 Extended periods out of radar coverage
 Large longitudinal and lateral
separation minima required for safe
procedural separation
 Most airlines want the same tracks and
altitudes  results in altitude
“congestion”
 Safe, efficient (from a traffic flow
perspective) operations but many times
not fuel efficient operations
Solution
Optimal
Compromise
 Aircraft “stuck” at a non-optimal
altitude due to traffic “congestion”
– For efficient operations, aircraft need
to climb as they burn fuel
– Due to traffic congestion at higher
altitudes, aircraft often restricted from
climbing
 Use airborne surveillance and
onboard tools to facilitate altitude
changes for greater fuel efficiency
3
South Pacific Oceanic Region
Overview and Technical Challenges
ATSA - ITP
 “Virtual tracks”
– Two types of routes – Fixed and User
Preferred Routes (UPR)
– Fixed routes do not account for wind or
weather (or airline efficiency considerations)
– UPR’s – optimized routes generated by
individual customers (preferred solution)
– Most UPR’s are generated by similar
programs based on same wind data so most
end up on similar routes
FL350
 Pairwise congestion
FL340
Flight #1
FL330
Flight #2
Flight #3
FL320
FL310
FL300
FL290
7
8
9
10
11
12
Time (hr)
13
14
15
16
– Aircraft leave the west coast of the United
States about the same time
– Aircraft generally end up causing altitude
restrictions to each other a portion of the
way into the flight
– Aircraft not able to operate as efficiently
due to traffic conflicts
4
Oceanic Non-Radar Airspace
Summary of Problems
ATSA - ITP
 Extended periods out of radar coverage
 Large longitudinal and lateral separation minima required for
safe procedural separation at reporting points
 Difficult for crew to get climb approval or predict when approval
may be granted
– Cleared for one altitude on entire track route (eg NATOTS)
– Pair-wise congestion preventing climbs when needed (eg SOPAC)
 Must carry (and possibly burn) contingency fuel
 Potential diversion if aircraft operates at significantly other than
optimal altitudes due to traffic constraints
 Difficult to escape a turbulent altitude due to pair-wise
“congestion”
5
TCAS In-Trail Climb
ATSA - ITP
The TCAS In-Trail Climb procedure built on an ICAO approved DME procedure
which allowed the controller to separate aircraft based on information derived
from cockpit sources and relayed by the flight crew



TCAS In-Trail Climb (1994) developed to allow aircraft to climb to more
efficient altitudes
– Distance determined by pilot using TCAS display
TCAS and voice radio used to positively identify traffic and determine the
distance behind traffic
– Traffic positively identified by cycling transponder from “on”, to “stand-by” , back to “on”
– Minimum distance = 15 miles
– Maximum distance = TCAS Surveillance limit (typically 25-40 miles)
No change in pilot/controller separation responsibilities
– ITC based on existing distance-based non-radar procedures
6
Airborne Traffic Situational Awareness - In-Trail Climb
ATSA - ITP
FL360
FL350
FL340
Current Separation
Requirement
blue = ADS-B transceiver and onboard decision support system
red = ADS-B out minimum required


As with TCAS in-trail climb, if traffic conflict geometry and dynamics are appropriate,
controller can approve climb based on information derived in the cockpit
– No delegation of separation responsibility
– Controller approves climb with knowledge of all aircraft (including non-equipped aircraft)
On-board system is used to provide required information and addresses TCAS ITC
deficiencies
– Use ADS-B “in” and on-board automation to provide target a/c flight ID, ground speed
and range information
 Eliminates need for communication with target a/c
 Addresses ALPA concerns with TCAS ITC (cumbersome procedures, safety system
cycled on and off, lack of flight ID)
 Eliminates TCAS dropped targets
7
Airborne Traffic Situational Awareness - In-Trail Procedures
ATSA - ITP
 Oceanic in-trail climb safety case can be developed based on an
update to the previously accepted TCAS ITC safety case
 For increased utilization of the procedures, other maneuvers can
be considered that utilize same equipment and similar procedures
 Further safety analyses need to be performed for these additional
maneuvers
 In-Trail Procedure broken up into six maneuvers
– In-trail climb
– In-trail descent
– Leading climb
– Leading descent
– Combination of in-trail and leading climb
– Combination of in-trail and leading descent
8
Airborne Traffic Situational Awareness - In-Trail Procedures
Increased Opportunities for Flight Level Changes
ATSA - ITP
Restrictions based on today’s procedures and standards
 Co-speed @ Mach .80  10 minute separation, ~80 nm required
 No climbs allowed if other traffic are in the red hatched area
FL360
FL350
-80 nm
80 nm
FL340
Opportunities for climbs using ATSA - ITP
 Maximum closure rate = 20 kts, minimum initiation range = 15 nm, minimum climb rate = 300 fpm
 No climbs allowed if other traffic are in the red hatched area
FL360
FL350
-15 nm
15 nm
FL340
9
Airborne Traffic Situational Awareness - In-Trail Procedures
Operator Benefits/Interest
ATSA - ITP
 Airline return on investment and resulting incentive to equip is key to any
operational implementation
 Airlines have been studying oceanic operations looking for potential
improvements
– “Small” changes to operations can result in significant fuel savings (long “leg” lengths)
– Oceanic operations compromise 30% of a domestic airline’s total annual fuel
consumption!
Aviation fuel cost per gallon
– Fuel costs increasing
 "On average, fuel accounts for 16 percent of airline
operating costs. Fuel prices are 55 percent higher
than one year ago. This could add between $8 and
$12 billion to our annual fuel bill and threatens to
strangle our modest projected return to profitability.
Instead of flying high, we could be left swimming in
red ink.“
 Giovanni Bisignani, Head, International Air
Transport Association, 27 May 2004
$1.10
$1.00
Domestic
$0.90
International
$0.80
Total
$0.70
$0.60
$0.50
$0.40
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
Source: Bureau of Transportation Statistics
– Flexible operations can also prevent flights from experiencing costly diversions
 Potential fuel savings of ~$160,000 per airplane per year
10
Airborne Traffic Situational Awareness - In-Trail Procedures
Detailed concept of operations

ATSA - ITP
Detailed concept of operations for improved oceanic operations
– Establish a single, globally accepted, Concept of Operations
– Results in a globally accepted set of standards for the procedure

Requirements Focus Group (RFG)
– Established to develop co-ordinated requirements across multiple ADS-B
applications to harmonize avionics standards

Oceanic ADS-B ITP Application Description (Operational and Service
Environment Description or OSED)
– ADS-B ITP Application Description development led by NASA and Airbus
 Co-Editors: Ken Jones (NASA), Stephane Marche (Airbus)
– Approximately 40 international participants contributed to the development of the
document
– Three versions of the document produced and released internationally for comment
– Two international workshops held to address substantive issues
11
Document Status and Statistics
Chronology
ATSA - ITP
 ATSA-ITP OSED version 1.0 sent to RFG members 11 April 2005
– Comments requested from RFG members by 22 April 2005
– Received 295 comments on version 1.0
– The comments were very good and many were accepted
 RFG ATSA-ITP OSED Meeting
– Held 17-19 May, 2005 in Washington, DC
– Addressed major issues on concept and phase diagrams
– Resolved most issues and had very few open items; most open items have since been
closed (others incorporated into the next set of comments)
 ATSA-ITP OSED version 2.0 sent to RFG members 10 June 2005
– Commenters were asked to self select the priority of the comments (high, medium, low
or editorial)
– Comments requested from RFG members by 22 June 2005
– Received 260 comments on version 2.0
– Majority of the comments were either “low” or “editorial”
12
Document Status and Statistics
Chronology (continued)
ATSA - ITP
 ATSA-ITP OSED meeting held at RFG/6
– Held July, 2005 in Malmo, Sweden
– Addressed issues on concept and phase diagrams
– Resolved all the major issues
 ATSA-ITP OSED version 3.0 sent to RFG members 5 August 2005
– Commenters were asked to self select the priority of the comments (high, medium, low
or editorial)
– Comments requested from RFG members by 9 September 2005
– Received 313 comments on version 3.0
– Majority of the comments were either “low” or “editorial”
– Next version to be released within the next couple of weeks
 ATSA-ITP Operational Hazard Assessment (OHA) workshop to be
held at RFG/7
– Held October 2005 in Brussels, Belgium
13
Airborne Traffic Situational Awareness - In-Trail Procedures
Procedure Development and Approval
ATSA - ITP
 Desire global acceptance and approval of new oceanic procedures
– Operators desire approved procedures that will be applicable in all oceanic
domains
– Implies ICAO approval required
 South Pacific ICAO Procedures Development and Approval
– NASA briefed the Informal South Pacific ATS Coordination Group (ISPACG)
briefing in February 2005
– Very interested in supporting and approving the procedure in the South Pacific
 North Atlantic ICAO Procedures Development and Approval
– NASA briefed North Atlantic Implementation Management Group (NATIMG)
briefing in April 2005 and the North Atlantic Air Traffic Management Working
Group (NAT ATMG) in September 2005
– NAT ATMG will use a portion of the OSED developed by the RFG as a starting
point for the ICAO procedure development
14
Oceanic ADS-B In-Trail Procedures (ITP)
Proposed ADS-B ITP Flight Trials
ATSA - ITP
 Goal
– Enable a 6 month operational flight trial of the proposed Oceanic ADS-B
In-Trail Procedures on partner revenue aircraft
 Objectives
– Assess economic and operational feasibility of ADS-B In-Trail Procedures
 Better understand system costs (flight deck, ground automation,etc.)
 Assess predicted benefits of ADS-B ITP
 Gain operational experience with ASAS technologies
– Establish basis for global ADS-B ITP implementation
 Lessons learned and data obtained will be used to aid implementation globally
 Participants/Location
– Evaluating Oakland/SOPAC flight trial
 Held preliminary flight trial meetings with potential partners
– Interest level is very high
– All participants desire to begin this within the next 18 months
– Planning fall workshop
15
Summary
ATSA - ITP
Airborne Traffic Situational Awareness - In-Trail Procedures
– Airborne ADS-B data and an onboard decision support system used to
enable climbs and descents that are not possible within today’s separation
standards
– Addresses limitations of the existing TCAS In-Trail Climb procedure
– Aircraft that choose to equip are able to perform these additional in-trail
maneuvers and achieve more optimal altitudes
– Results in more efficient and predictable flight profiles which translates into
fuel savings and greater payload capacity
– Design goals
 Buy its way into the cockpit (voluntary operator participation)
 Global interoperability (where adopted)
 Possible growth path
 Benefit for first to equip (without disincentive for non-equipped)
16
Back Up Slides
ATSA - ITP
17
Airborne Traffic Situational Awareness - In-Trail Procedures
Detailed Procedures
ATSA - ITP
 Procedure description broken up into 4 phases
Initiation, Instruction, Execution, and Termination
 Definitions and Terms are key to understanding the procedure
Other
Aircraft
Other
Aircraft
Reference
Aircraft
Other
Aircraft
ITP
Aircraft
Standard
Longitudinal
Separation Requirement
Potentially
Blocking
Aircraft
ITP
Criteria
Standard
Longitudinal
Separation Requirement
Requested
Flight
Level
Intervening
Flight
Level
Current
Flight
Level
18
Airborne Traffic Situational Awareness - In-Trail Procedures
Detailed Procedures – ITP Initiation
ATSA - ITP
Qualifications/Preconditions for Conducting the ITP
–
–
–
Airline operational specifications permit ITP
Flight crew of ITP aircraft is properly qualified for ITP maneuvers
ITP aircraft must:
 Have ITP equipment, providing flight crew with flight ID, range and ground speed differential to
potentially blocking aircraft
 Have own-ship position data accuracy meeting requirement for ITP
 Be on a same track with potentially blocking aircraft
–
Requested flight level shall be:
 One same direction flight level above/below one intervening flight level
 No more than 4000 feet above/below current flight level
ITP Initiation Criteria
–
Range and ground speed differential criteria are met, for example:
 Range from ITP aircraft to reference aircraft is greater than 15NM, and
 Positive ground speed differential is less than +20 knots
–
–
Reference aircraft has qualified ADS-B
ITP aircraft’s performance will enable a vertical speed of at least +/-300 fpm at assigned
Mach number to requested flight level
ITP Request
–
If ITP qualifications/preconditions and criteria are met, ITP aircraft crew requests ITP,
providing the controller with flight ID and range of reference aircraft
19
Airborne Traffic Situational Awareness - In-Trail Procedures
Detailed Procedures – ITP Instruction
ATSA - ITP
Controller ITP Clearance Issuance
– If safe longitudinal separation will be maintained, a standard flight level
change clearance may be granted, if not
– Controller:
 validates flight ID of Reference Aircraft
 determines there is no greater than +0.03 Mach difference
 verifies Reference Aircraft is not in the process of changing its flight level or
direction
– Based on the ITP Aircraft’s request and controller’s determination, the
controller would grant ITP request
ITP Crew Re-Assessment
– After ITP clearance is issued, ITP Aircraft crew must again determine
that ITP criteria are met immediately before initiating climb or descent
20
Airborne Traffic Situational Awareness - In-Trail Procedures
Detailed Procedures – ITP Execution
ATSA - ITP
During the ITP Maneuver
Crew performance
– Crew must:
 initiate ITP without delay after receipt of clearance,
(no different than initiating a standard climb or descent clearance)
 strictly adhere to assigned Mach number during maneuver
 maintain a minimum +/-300 fpm vertical speed throughout maneuver
– ITP aircraft crew is not required to monitor the range to reference aircraft during
climb or descent.
– ITP flight crew reports established at new flight level
Controller performance
– After issuance of the ITP clearance, controller will:
 protect ITP aircraft’s initial flight level until it reports established at new flight level
(for non-normal case where ITP aircraft must return to initial flight level)
 not issue any maneuver clearance to reference aircraft until ITP aircraft reports
established at new flight level
21
Airborne Traffic Situational Awareness - In-Trail Procedures
Detailed Procedures – ITP Termination
ATSA - ITP
ITP Termination
– ITP is completed when ITP aircraft flight crew reports established
at new flight level
– If ITP aircraft must return to its initial flight level, an abnormal
termination occurs
22
TCAS In-Trail Climb/Descent Chronology
ATSA - ITP
 Trial procedure approved for use in Oakland and Anchorage FIRs
– Only United and Delta approved for Phase 1 trials (10/94 – 3/96)
 Both aircraft (the lead aircraft, and the one performing the ITC) had to be qualified
 Phase 1 ITC trials
– 68 ITCs requested and 37 ITCs performed in first 18 months of trial (10/943/96)
– Limited utility due to
 Both aircraft had to be participating (i.e. United and/or Delta)
 Limited TCAS range, unreliability of TCAS at longer ranges to reacquire traffic
when transponder cycled
 Subsequent Actions
– Rapidly fell out of favor, partially due to ALPA concerns
– Airlines removed ITC procedures from their Aircraft Flight Manuals in 2000
– United has put TCAS ITC back in their manuals in the Pacific, primarily as a
tool for turbulence avoidance
 Airline Pilots Association (ALPA) expressed concerns over the
procedure
– Safety system cycled on and off
– Lack of flight ID on display
23
Operator Efficiency Considerations
Fuel Burn Comparisons by Altitudes Flown
Unrestricted Altitude Crossing (UAC)
Boeing 777-200B
(Eastbound in NATOTS)
50º
ATSA - ITP
Minimum Burn Level Crossing (MBLC)
40º
30º
20º
10º
400
∆= -112 lbs
390
∆ = 3148 lbs
∆ = 1022 lbs
∆=
0 lbs
∆ = 196 lbs
∆ = 835 lbs
∆ = 2099 lbs
∆ = 3587 lbs
∆ = 5353 lbs
380
370
FL(feet)
360
350
340
330
320
310
300
290
0
1
2
3
4
Time(hrs)
Note: Data is for a Boeing 777-200B at Mach .84 with a track entry weight of 530,000 lbs. This is for a standard day with zero winds.
Approximate location for waypoint reporting points.
24
Atlantic and Pacific
Oceanic Regions and Route Structures
ATSA - ITP
NATOTS

Fixed Routes (eg., CEP)
–
–
–

EUR-NAM
PACOTS
CENPAC
WATRS
EUR-CAR
CEP
SOPAC
Organized Track Systems (eg., NATOTS, PACOTS)
–

Fixed routes similar to domestic
airway structure
Do not account for changing
wind or weather conditions
Reduce complexity for ATC,
but are not always most
efficient for customers
Flexible track system established by ATSP’s, utilizing forecasted weather conditions to produce the
most time/fuel efficient routes for a representative city pair (established daily)
User Preferred Routes (UPRs)
–
–
Optimized routes generated by individual operators based on aircraft type, aircraft loading, weather
and flight plan requirements
Advantages include optimum cruise trajectories (altitudes, routes), improved fuel efficiency,
increased predictability on fuel usage and payload capacity
25