1. ASSTAR Oceanic Session Summary
Advanced Safe Separation Technologies and Algorithms
ASSTAR User Forum #1 at ASAS-TN2 Workshop in Rome, 4th April 2006
ASSTAR Oceanic Session Summary

2. Intent of target aircraft during SSEP Free Flight Manoeuvre
Is target aircraft expected to fly straight during SSEP-FFT procedure? If not, how does aircraft using procedure know about intent of target?
Issue will be handled by conflict detection/resolution application in both aircraft. The procedures will be based on state information, only. Intent information on target aircraft is not foreseen to be required.
It should be noted that both aircraft in FFT will be active.
ASSTAR User Forum #1 in Rome, 4th April 2006

3. ASSTAR User Forum #1 in Rome, 4th April 2006
Safety Assessments - Differences between ATSA and ASEP ITP Applications (1/2)
Shouldn't the safety assessment for ASEP-ITP be very different from that for ATSA-ITP? The safety concerns for ATSA have been addressed by the RFG and are relatively easy, while the ASEP procedures need in-depth analysis, similar to that for ground surveillance.
ASSTAR does not claim to proceed the safety case to the very end, but rather to compare the applications and their safety benefits.
The difference of the applications will be taken into account, but the methodology to assess this will be the same.
The results on risk calculation prepared by NASA for ATSA-ITP will be taken into account and changes for ASEP-ITP will be quantified.
The RFG has analysed ATSA to identify any major safety concerns.
Mitigation means are required in case of ASEP equipment failure.
ASSTAR User Forum #1 in Rome, 4th April 2006

4. ASSTAR User Forum #1 in Rome, 4th April 2006
Safety Assessments - Differences between ATSA and ASEP ITP Applications (2/2)
ASSTAR will do a preliminary assessment of hazards and identify differences in the cockpit application between ATSA and ASEP. (Differences not known, yet)
This preliminary assessment, together with initial procedures, will then be taken into account for the airborne and ground infrastructure definition.
ASSTAR aims to identify and address relevant risks (e.g. loss of functionality, incorrect display of information, ...).
Integrity issues of position sources will not be investigated in detail, the existence of such sources with sufficient accuracy and integrity will be taken for granted.
ASSTAR User Forum #1 in Rome, 4th April 2006

5. Airborne Separation Minima Standard
General discussion on airborne separation standard between two aircraft, noting the difference between ADS-B navigation errors and RNP position and guidance errors and the possible need for an Oceanic reference.
For ATSA-ITP, the RFG have used analogy to TCAS-ITC and DME- based separation. However, spacing calculations will be dependent on the lead aircraft‘s ADS-B data.
Quality of ADS-B data (declared in transmissions) will have an impact on the separation standard. RNP-4 will probably be assumed as a starting point, although it is not a driver for the separation minima.
Separation minima of a much lower value in comparison to the current procedural separation should be readily achievable, still enabling very significant benefits to be obtained from the applications. Also, capacity over the NAT is not an issue driving lower separation minima. This could lead to early widespread adoption.
ASSTAR User Forum #1 in Rome, 4th April 2006

6. Monitoring Task of Crew
Is the crew required to monitor the separation during ITP? If so, doesn't this require some sort of alerting function?
For ATSA-ITP, there is no need for monitoring once the clearance has been issued. In fact, the ATSA equipment may fail completely during the manoeuvre without effecting the procedure at all.
For ASEP-ITP, the crew needs to monitor, but the manoeuvre will take only a few minutes. Automated alerting may be provided.
For ASEP-ITF, which can last several hours, automated alerting will be a requirement.
In reality, the crew WILL probably observe the progress of the manoeuvre. The issue of what they do if they see something wrong needs to be addressed.
ASSTAR User Forum #1 in Rome, 4th April 2006

7. Lateral Procedures and Full SSEP
Why does ASSTAR not investigate lateral manoeuvres (i.e. overtaking) in ASEP since this is more useful in oceanic airspace?
For the first 6 months of ASSTAR, several manoeuvres were investigated, including lateral overtaking, but we needed to focus on a few procedures.
After the User feedback of the first User Workshop, lateral overtaking was not on the top of the list, potentially due to high requirements on aircraft equipage.
Also, an overtaking manoeuvre in oceanic airspace will take quite long (several hours) due to relatively small speed differences.
Why not establish the maximum savings from full free-flight separation manoeuvres? We want to get on with ASAS now.
Believe that Users want introduction of ASAS to be in a controlled series of steps of increasing complexity and integrity.
ASSTAR User Forum #1 in Rome, 4th April 2006

8. Impact of headwinds on ASEP-ITF
Are the dynamics of the jet streams taken into account? If aircraft are operating ASEP-ITF and encounter headwinds, then the spacing distance will reduce rapidly to the lead aircraft.
This situation needs to be addressed in the choice of algorithms.
NLR favour a time-dependent approach.
ASSTAR User Forum #1 in Rome, 4th April 2006