1. ASSTAR Airborne Separation Applications
Craig Foster
Probably need a short bio…
Masters in Mathematics from Imperial College, London
Decided not to work in the City but to try his hand at making a fortune in the air traffic management industry.
Started work on operations research concepts and projects including separation monitoring and risk to third parties.
Moved on to manage the operational monitoring of TCAS in UK airspace.
Then moved in to NATS R&D and worked on ADS-B monitoring and managed the CRISTAL UK project which was NATS first ADS-B operational trial. Culminating in the development of NATS strategic direction for ADS-B and multilateration technologies.
In addition to all this, since June has also followed the career path for anyone who has ever worked on TCAS and moved on to lead NATS ASAS research portfolio.
Your programme will say Mark Watson should be presenting this talk.
As you can see I’m not Mark he sends his apologies but he is in the process of moving house so since he’s not here I can say that you are lucky to have the younger, fitter, taller, more hair, more handsome, possibly less controversial version
Restricted to the ASSTAR template – so sorry to disappoint those who wanted to see NATS new stripy branding

2. Contents Describe ASSTAR Applications
Concept
Environment
Commonalities Between Applications
Use of Datalink
An Operational (ANSP) Viewpoint
Hopefully Short presentation with a simple brief to describe the ASSTAR applications.
Since this is an ASAS conference I should be preaching to the choir although I’ll spend a bit of time on the oceanic environment as this is possibly new to some.
In addition it is interesting to note some of the ASSTAR observations on the commonalities of the applications
I’ll also present some thoughts on the use of datalink and an ANSP view.
Again personal opinions – not speaking for NATS policy

3. Operational Concept Airborne Separation Applications
Controller delegates separation responsibility and transfers separation tasks to the flight crew
Flight crew ensure applicable airborne separation minima are met
Responsibility limited to separation from a designated aircraft
Separation provision still the controller’s responsibility
Self-Separation Applications
Require flight crews to separate their flight from all surrounding traffic
In terms of the PO-ASAS categories we are considering 2 responsibility levels –
the Airborne Separation (ASEP) applications
Delegation of separation limited to single designated aircraft.
Separation provision of that aircraft from all other aircraft still the controller’s responsibility.
Self separation
The extension whereby we require the aircraft to separate itself from all other aircraft.

4. Applications by Responsibility
Separation Applications
Crossing & Passing (ASEP-C&P)
In Trail Follow (ASEP-ITF)
In Trail Procedure (ASEP-ITP)
Self-Separation Applications
Free Flight Track (SSEP-FFT)
New Application from Glasgow ASAS-TN Workshop
In Trail Merge (ASEP-ITM)
Radar Airspace
Oceanic Airspace
The applications which were identified at earlier user workshops and then explored were
At the ASEP level
Advanced crossing and passing
ITF
ITP
And at the SSEP responsibility level FFT
We have also just begun exploring an application which my colleague Bob McPike presented at the Glasgow ASAS-TN which we have called ITM
We are considering these applications in two environments
Radar airspace
Oceanic airspace

5. ASEP-C&P Turning Point
First the radar airspace application ASSEP C&P
Description
To allow a controlled and suitably ASAS equipped aircraft to modify its horizontal trajectory in order to achieve lateral separation by itself (airborne separation) from another converging controlled flight independently of vertical profile
Expected benefits
With no change in current ground separation minima, capacity and flight efficiency gains are expected by allowing aircraft to fly more closely to their original flight plan and possibly reducing the number of deviations from flight plan
Presently, the actual distances for crossing aircraft exceed the applicable separation minima in radar airspace by a large margin. This is because the air traffic controller anticipates and manages his workload by issuing early spacing manoeuvre instructions
The operational environment for this application is envisaged to be radar en-route airspace in Europe

6. ASEP-C&P - Offset
1st algorithm considered a single turning point – second considers the other method of flying an offset.
Needless to say the methods considered were both pass in front and pass behind.

7. Oceanic Environment
No VHF Radio or radar cover over most of the North Atlantic Region (NAT)
Voice communications provided by High Frequency (HF) Radio
HF subject to weather effects
Audibility can be limited
Sometimes impossible
So ATC issues strategic clearances
Issued prior to entering Oceanic FIR
Extend from Oceanic Control Area (OCA) entry to landfall
Long-term conflict prediction used to ensure no separation loss over whole route
That was the radar airspace application. Before moving on to describe the oceanic applications it is beneficial to quickly describe the oceanic environment since it is quite specialised and may be unfamiliar to some.
We can’t see aircraft, and sometimes we can’t talk to them, so ATC issues strategic clearances
Cleared from entry to landfall using long-term conflict prediction.
Organised Track Structure

8. Organised Track Structure
Diurnal pattern of eastbound in the morning and westbound in the evening.
Each day establish the organised track structure
5-6 parallel tracks
Based on weather patterns and airline demand.
NATS responsible up to 30W

9. Oceanic Separations 10 mins 15 mins 60 miles 1000 ft
Separation standards governed by various uncertainties:
Communication unreliability
Navigational accuracy
Accuracy of forward estimates (driven by weather forecasts)
. . . so separation standards are very large
10 mins
60 miles
1000 ft
15 mins
Separation standards are governed by various uncertainties, principally:
Poor reliability of HF
Some aircraft still have no GPS and lack of surveillance means GNEs can be difficult to detect
Reliance on forward estimates for strategic clearances based on 12 to 24 hour forecasts
For aircraft through a common point – 10 minutes longitudinal
If not through a common point – 15 minutes as weather inaccuracies may not be the same for both aircraft
Use ADS-C or HF position reporting to maintain situational awareness.

10. SAATS
System which is used is SAATS Shanwick Automated Air Traffic System
Developed in collaboration with NavCanada extension of the GAATS systems - important as effectively moving towards a commo platform for te Ocean – only responsible up to half way – common platform has obvious benefits
Paperless flight strips, integrated Datalink communications and ADS-C reporting
Went in to operational service 21st November 2006 on time and budget.
SAATS replaced the NATS Oceanic FDPS1 System, which entered service in October 1987, was formally switched off for the last time on 22 February 2007.    FDPS1 was the CAA's second Oceanic system, in 1987 it replaced an earlier system hosted on Ferranti Apollo equipment.    The Ferranti Apollo, from 1961, was a landmark:  the world's first use of a digital computer for air traffic management.
The oceanic operation is procedural which might make it seem a bit parochial but it has very advanced systems and embrases new technology

11. OAC Movements 2002
Illustrate show some reasonably recent movement figures to show the scale of the operation.
Come a long way since Alcock and Brown performed the first non-stop flight across the Atlantic on
14th June 1919, with a flight time of 15hours 52 minutes.
Now on to the ASAS applications being considered in ASSTAR
Charles A. Lindbergh's 1927 achievement, winning the Orteig Prize, which was the first solo crossing, and also the first nonstop airplane crossing from the American mainland to the European mainland, Lindbergh was the 104th person to fly the Atlantic.

12. ASEP-ITP (In Trail Procedure)
But standard longitudinal separation does not exist at level above
Crew request an ITP Climb
Aircraft at FL340 would like to climb …..
> 10 mins
> 10 mins
FL360
FL350
ATSA-ITP Criteria
5 mins
Aircraft at FL340 would like to climb . . .
. . . but climb is prevented due to insufficient longitudinal separation from the aircraft at FL350
. . . although required separation is available at FL360
If ITP criteria are met (340 aircraft ADSB in/out, 350 a/c ADSB out, min sep and max closing speed) crew can request an ITP climb
ATC issue ITP clearance
a/c climbs to FL360 where he has required long sep
Manoeuvre complete
Based upon Package 1 application ATSA-ITP
Differences
Active monitoring phase during flight level change
Aircraft are responsible for separation
Similarities
Applicability conditions unchanged
FL340

13. ASEP-ITF (In-Trail Follow)
Second climb approved –Maintaining ITF Separation
In-Trail Follow cancelled
Exit Oceanic Airspace
Climb Approved, Maintaining In-Trail Airborne Separation
In-Trail Separation maintained over extended period
Airborne Separation Established: In-Trail Follow
5 minutes : No standard longitudinal separation
FL360
FL350
ITP is only suitable for 2000’ climbs – but suppose a 1000’ climb is required
a/c at FL340 wants to climb to FL350
If ITF criteria are met (340 aircraft ADSB in/out, 350 a/c ADSB out, min sep and max closing speed) ATC can issue an ITF clearance
ITF separation established – red aircraft now responsible for monitoring and maintaining designated separation from lead aircraft
Aircraft climbs
ITF maintained over required period
Aircraft requests a second climb
ITF maintained until established at FL360
ITF cancelled
Based upon Package 1 application ASPA-S&M
Differences
Aircraft are co-altitude
Aircraft are responsible for separation
Extended duration (several hours)
Spacing defined in minutes rather than seconds
Similarities
Procedural termination condition - exit from track
Merge instructions can be used to initiate spacing at track entry
Benefits
Aircraft Operator
ITP
Increased level change opportunity & hence ability to fly at preferred level
Reduced Fuel Burn
Cost
Environment
ITF
Substantially improved availability of preferred level (ITF)
ANSP
No significant controller workload impact (ITP)
Reduction in controller workload (ITF)
ITF
5 mins
FL340

14. SSEP-FFT FFT is an OTS track reserved for ASAS-capable aircraft
Aircraft on the track can change speed and level at their own discretion
. . . but no lateral flexibility allowed
Aircraft requires downstream clearance to re-enter managed airspace
Anticipated Benefits
enabling more aircraft at the flight levels of a track (due to lower longitudinal separation criteria)
enabling more frequent flight level changes or even cruise climbs
enabling more freedom in speed selections
these factors contribute to better flight efficiency, improved track occupancy and improved safety
controller workload reduction
SSEP-FFT characteristics
Separation responsibility relative to all aircraft on the Free Flight Track is transferred to the flight crew, for an extended period of time
New entry/exit procedures will be required
aircraft will receive a clearance to enter the Oceanic Free Flight Track
aircraft will receive a clearance to return to managed airspace
An Oceanic Free Flight Track has to be defined (in space, in time, legally)
Benefits
Aircraft Operator:
Substantially Improved Flexibility to fly at preferred level and speed
Airline cost saving (reduced fuel-burn)
Environmental benefits (reduced fuel burn)
Adverse impact on flexibility for non-equipped aircraft?
ANSP:
Substantially reduced controller workload for normal operation
But adverse impact on ATC ability to manage non-normal conditions?

15. Tactical re-routes in the NAT
The motivation for the ITM procedure.
This idea was first described at the ASAS-TN in Glasgow
Eastbound oceanic traffic is a major problem for European domestic centres
Traffic is highly concentrated, with up to 700 flights arriving in a short period and at the same time as the first rotation of domestic services
Results in a high number of complex interactions which is often managed by restricting domestic flights
Proposals for reduced lateral and longitudinal separations in the NAT will lead to even higher traffic concentrations
At the moment, OTS traffic presents over a wide front (300+ NM)
If lateral separation is reduced to 30 miles, the same traffic volume could be concentrated into 150 NM, forcing domestic sectors to introduce flow restrictions to protect themselves
An alternative would be to allow traffic to concentrate for most of the crossing, then to spread out (laterally and vertically) to spread the load across a wider number of sectors

16. ASEP-ITM (In Trail Merge)
15 minutes
4 minutes
ITM
New WP-8 to investigate
Opportunities
Procedures
The problem with spreading traffic at present is the 15 minutes separation required for traffic not through a common point
ITM, however, would allow traffic to switch tracks at much lower separations, typically 3-4 minutes
ITP/ITF would also be used to create a vertical spread by moving (e.g.) traffic for London TMA to lower levels
Subject of the new ASSTAR WP-8 which will describe the procedure, identify the conditions for use and so identify the scale of opportunities for this application. Initial OSED draft under review but still under construction.

17. Application Commonalities
Equipment
ADS-B IN
CDTI functionality
Require High ADS-B Out equipage
Common phases of application
ATC
Institutional issues for delegation
Transition issues - from today to tomorrow
Interface with managed airspace
Early adopters of ADS-B in get the benefits but require the aircraft population to have a high level of ADS-B Out equipage
What should the requirements be – as strict as for RAD or NRA?
Phases similar
Identification, Clearance, Execution, Termination
Same equip, same procedures for setting up,
ATC commonalities
implications of delegation to the pilot
SSEP ATC still aware of what’s going on in case it all goes wrong and we’re managing the surrounding tracks.
our dependence on them and how do we get assurance that they can carry out that procedure
Transition issues
same issues 3rd party ID,

18. Use of Datalink
Assumed that this is post-Package 1 and that ADS-B IN (and data link) would be available.
All ASSTAR applications designed to use both HF voice communications and datalink…
… but we wouldn’t want to use HF
Only consider these applications in a datalink environment
Designed to use either HF or datalink
However, messages are long, complicated and
HF is not ideal for the task.
Only consider these applications using a datalink
Current equipage 40% CPDLC and ADS-C

19. Operational Perspective - NATS
Potential environmental and cost benefits to our customers
NATS needs to understand the implications of implementing
Capacity effects of FFT
Control of adjacent tracks
Management of traffic at the domestic interface
Regulatory issues
Need for harmonised approach with adjacent ANSPs
Exploring other complementary options
Improved Vertical Profiling (IVP)
Applications have potential
Implications of airlines wanting to use these application on NATS ability to manage this operation
effects of FFT if best route given to only a select few
control of aircraft on adjacent tracks and integration issues
management of traffic once it gets to the other side – flow must be controlled and managed appropriately
regulatory issues may be significant hurdle – delegation (no different to all ASEP)
must be a complete solution for the ocean which means working with adjacent ANSPs to ensure commonality of approach: ISAVIA NavCanada
Personal view. These ASAS applications are still firmly within the R&D domain.
Considering other options including
IVP – ground-based solutions, benefits explored, sims underway
Positive ITF/M/P all complementary to current plans for oceanic airspace development
SEE D4.2

20. Thank you for listening

21. Operational Perspective - DSNA
DSNA intentions in ASSTAR:
Opportunity to re-activate and extend visual separation clearance used in the past.
New sharing of tasks between air and ground should have a positive impact on ATCO workload
Capacity effects of C&P for the ATCO
Flight efficiency of C&P