1. 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

2. Outline
Background
Oceanic Challenges
TCAS In-Trail Climb/Descent
Airborne Traffic Situational Awareness – In-Trail Procedure
Overview
Chronology of RFG activities
Summary

3. North Atlantic Organized Track System Overview and Technical Challenges
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
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
Solution
After talking to potential partners, particularly airline operators, we determined getting close to optimal altitude was the most important thing to do
However, optimal climbs are not feasible in a track environment. What we are trying to do is to get closer to optimal with step climbs.
Right now the mental model with operators is that they will not get any climbs and are stuck at one altitude (the compromise altitude). That altitude is not too bad but if you get far off of that altitude, you pay a big penalty in fuel burn.
Point out track graphic.
Optimal
Compromise

4. South Pacific Oceanic Region Overview and Technical Challenges
“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
The situation in the Pacific region is slightly different. You don’t have hundreds of aircraft like you do in the Atlantic but the small number that fly are still affecting each others altitude selection (as seen in the lower left graphic).
What really hurts these flights is that they are often flying at max gross weight. If they know that they can avoid being stuck at an inefficient altitude (due to more flexible maneuvers), they can carry less contingency fuel and more high value payload (which can make them a lot of money). But they need the more flexible operations.
Pairwise congestion
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

5. Oceanic Non-Radar Airspace Summary of Problems
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”
This is a summary of what was said.

6. TCAS In-Trail Climb
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 miles)
No change in pilot/controller separation responsibilities
ITC based on existing distance-based non-radar procedures
TCAS In-Trail Climb was never an approved ICAO procedure. But it did take advantage of building off an ICAO DME procedure.
It did take advantage of surveillance information on the flight deck (in the form of TCAS) to be able to perform a new maneuver.
There were concerns by ALPA about this procedure (and it was a bit cumbersome) and so it was not used a lot.

7. Airborne Traffic Situational Awareness - In-Trail Climb
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
An ATSA-ITC is similar to the TCAS-ITC but it uses a different surveillance technique and is a much easier procedure.

8. Airborne Traffic Situational Awareness - In-Trail Procedures
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
Most of this is fairly self-explanatory. The one important thing for North Atlantic people is that the combination will be important for NAT OTS traffic situations (due to the density of the traffic).

9. Airborne Traffic Situational Awareness - In-Trail Procedures Increased Opportunities for Flight Level Changes
Restrictions based on today’s procedures and standards
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
The key here is that you can not climb if someone is in the red hatched area. That red hatched area is much smaller for the ATSA-ITP.
FL360
FL350
-15 nm
15 nm
FL340

10. Airborne Traffic Situational Awareness - In-Trail Procedures Operator Benefits/Interest
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!
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
Source: Bureau of Transportation Statistics
Aviation fuel cost per gallon
Most important point is that airlines will save money if they equip. Hopefully they will get a positive return on investment within months.
Flexible operations can also prevent flights from experiencing costly diversions
Potential fuel savings of ~$160,000 per airplane per year

11. Airborne Traffic Situational Awareness - In-Trail Procedures Detailed concept of operations
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
Ideally there is one global concept of operations. RFG is a unique opportunity to develop that!

12. Document Status and Statistics Chronology
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 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”

13. Document Status and Statistics Chronology (continued)
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

14. Airborne Traffic Situational Awareness - In-Trail Procedures Procedure Development and Approval
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
It is important to have globally accepted procedures (as well as standards). That is an ICAO function and they are being briefed on the RFG work and being able to use that as a starting point for their procedure development.

15. Oceanic ADS-B In-Trail Procedures (ITP) Proposed ADS-B ITP Flight Trials
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

16. Summary 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)

17. Back Up Slides

18. Separation Requirement Separation Requirement
Airborne Traffic Situational Awareness - In-Trail Procedures Detailed Procedures
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
Requested
Flight
Level
Reference
Aircraft
Other
Aircraft
Potentially Blocking
Aircraft
In service evaluation
Intervening
Flight
Level
ITP
Aircraft
ITP
Criteria
Current
Flight
Level
Standard
Longitudinal
Separation Requirement
Standard
Longitudinal
Separation Requirement

19. Airborne Traffic Situational Awareness - In-Trail Procedures Detailed Procedures – ITP Initiation
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
In service evaluation

20. Airborne Traffic Situational Awareness - In-Trail Procedures Detailed Procedures – ITP Instruction
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 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
In service evaluation

21. Airborne Traffic Situational Awareness - In-Trail Procedures Detailed Procedures – ITP Execution
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
In service evaluation

22. Airborne Traffic Situational Awareness - In-Trail Procedures Detailed Procedures – 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
In service evaluation

23. TCAS In-Trail Climb/Descent Chronology
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 (10/94-3/96)
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

24. Operator Efficiency Considerations Fuel Burn Comparisons by Altitudes Flown1 2 3 4
Time(hrs)
290
300
310
320
330
340
350
360
370
380
390
400
FL(feet)
10º
20º
30º
40º
50º
Note: Data is for a Boeing B 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.
∆= lbs
Unrestricted Altitude Crossing (UAC)
Boeing B
(Eastbound in NATOTS)
Minimum Burn Level Crossing (MBLC)
∆ = lbs
∆ = 3148 lbs
∆ = 1022 lbs
∆ = lbs
∆ = lbs
∆ = 2099 lbs
∆ = 3587 lbs
∆ = 5353 lbs

25. Atlantic and Pacific Oceanic Regions and Route Structures
NOPAC
NATOTS
Fixed Routes (eg., CEP)
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
Organized Track Systems (eg., NATOTS, PACOTS)
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
PACOTS
EUR-NAM
CENPAC
WATRS
EUR-CAR
CEP
SOPAC
Examples of the first:
Analysis of enhancements in navigation, situation awareness from increased datalinks to cockpit
Evaluation of Air-Ground datalink communication needs & impact on NAS capacity & other benefits
Develop framework for a new digital communication architecture that can provide the services for today's NAS and future operational changes in terms of satellites needed, ground networks, coverage, redundancy, data rates, etc.