1. ATFM Priorities Evaluation Study Alison Hudgell QinetiQ
Presentation to EUROCONTROL/FAA Action Plan 6 TIM 8 “Collaborative Decision Making Applications in Air Traffic Flow Management”
ATFM Priorities
Evaluation Study
Alison Hudgell
QinetiQ

2. Background
“ATFM Priority Options” Study (1998) for European Commission
how to reduce operational impact of congestion
considered chronic congestion and “crises”
stakeholder interviews
proposed prioritisation strategy options
EUROCONTROL commissioned to validate proposals through simulation
ATFM Priorities Evaluation Study (2000-1)
Chronic congestion - saturation of ATC capacity on a repetitive basis, over an extended period of time
Crisis - big difference between available capacity and traffic demand, over short period. Could be: - reduction in capacity - increase in demand
Current rule is First Planned, First Served (as we have probably heard)
Proposing alternative strategies, with the aim of reducing operational impact.

3. Agenda Project Background Assessment criteria Proposed ATFM strategies
description
assessment
recommended next steps
Conclusion

4. Assessment Criteria Feasibility of technical implementation
Potential abuses & feasibility of verification
Implementation acceptability to stakeholders
Frequency or range of applicability
Benefits: delay reduction and split amongst target population
Impact on ATFM performance
July 2000 traffic used, some Saturdays, some weekdays

5. Overview of Strategies
“Global” Solutions -
Slot Allocation
Prioritised by:
Flight Type
Least Consumer Cost
Flight Distance
CDM Procedures for Prioritisation of Particular Flights
Integration of AO Tactical Priorities
Selective Amelioration
Airport Public Order Exceptions
Burden Sharing
Public Comment Proceedings
…will explain each in turn, with assessment conclusions

6. Global Prioritisation Strategies
Current: First Planned First Served
all flights are equal
Proposed: Prioritisation by ...
Flight Type - some types more time-critical
Consumer Cost - equity per passenger
Flight Distance - equity over day’s operation
Modified slot allocation algorithm to prioritise flights by category
Redistribute delays across flight categories
Least Consumer Cost really done per seat (easier to assess).
Could also include freight, by weight, in a model of “consumer cost”.
Flight Distance short-haul flights make several sectors in a day - delay on each sector adds up.
These are alternatives - different views of equity.
Intend to apply one or another, not in combination!
Possibly different models might be appropriate at different times/regulations
Different implementations tried
- full prioritisation (allocate all 1st category flights first, then next category, …)
- partial prioritisation (weighted function using ETO and rank)
- different weights

7. Global Prioritisation Strategies (2)
Flight Type  rejected
75% of regulated flights in high-priority class
prioritisation ineffective
problems of verification / policing
Least Consumer Cost  rejected
categorisation / validation more feasible
redistributes delay from larger to smaller aircraft
negative impact on hub operations
Flight Type
Least Consumer Cost
categorisation easier to tune
(70% has 100 seats+; seats = 50%; seats = 20-25%)
aircraft size easier to verify but - pax number more difficult; - what about freight?
Negative impact on hub operations
- smaller flights delayed more = feeder flights, => knock-on delays to long-haul flts

8. Flight Distance Results Recommended next steps
equal-sized categories most effective
“strength” of prioritisation can be tuned
with 5 equal categories; weight: 20% to prioritisation / 80% to FPFS
improved hub management
Recommended next steps
stakeholder consultation/analysis concerning strength of prioritisation
dynamic slot allocation algorithm
flight duration is verifiable
“equal-sized categories” => categories with equal populations of flights
- but traffic distribution varies with day/time and location (more work needed to develop best approach - good average classification to avoid flight being treated differently on dfferent days?)
strength of prio can be tuned by adjusting relative weight given to FPFS order and ranking in slot allocation algorithm

9. Overview of Strategies
“Global” Solutions -
Slot Allocation
Prioritised by:
Flight Type
Least Consumer Cost
Flight Distance
CDM Procedures for Prioritisation of Particular Flights
Integration of AO Tactical Priorities
Selective Amelioration
Airport Public Order Exceptions
Burden Sharing
Public Comment Proceedings

10. Integration of AO Tactical Priorities
“Slot Swapping” and “Substitution on Cancellation”
AO to decide on swaps between flights
limitiation: same regulations in same order
Modelled Operational Implementation
swap flights only of same AO
minimum improvement: 5 minutes
SIT1A < CTOTB - taxi time - margin for swap
50% of CFMU flights pass through more than one regulation
How many cases?
What impact on ATFM?
-> simualtion to find out

11. Estimate Number of Slot Swaps
1 in 3 “feasible” swaps is required (random selection)
Each flight may swap only once (random selection)

12. Slot Swapping - Conclusions
Estimate swaps per day
daily delay savings on critical flights of 1600 to 4000 minutes
No disbenefit to non-swapping operators
No systematic impact on bunching or overload
Recommended next steps
define procedure and rules
trial implementation
More opportunities on crisis days
Flag carriers at each of Europe ’s most congested hubs (not surprisingly) get largest number of potential swaps
No dis-benefit to other operators
Daily delay saving: to 2400 mins on «normal» days, - over 4000mins on 7/7/00=crisis day
At 25euro/min (IATA figure) => - 40,000 to 60,000 euro on normal days - in excess of 100,000 euro in crisis case

13. Overview of Strategies
“Global” Solutions -
Slot Allocation
Prioritised by:
Flight Type
Least Consumer Cost
Flight Distance
CDM Procedures for Prioritisation of Particular Flights
Integration of AO Tactical Priorities
Selective Amelioration
Airport Public Order Exceptions
Burden Sharing
Public Comment Proceedings

14. Selective Amelioration
AOs request amelioration of delayed flights that have become critical - e.g.
airport curfew
air-crew rostering
transfer passengers
Ad-hoc process exists today
Need to limit number of cases
agreed constraints?
quota system
Selective Amelioration of Serious, Unplanned Constraints
e.g. of constraints: - destination airport curfew - air crew roster - aircraft turnaround problems (e.g. flight technical) - significant number of transfer pax - just-in-time freight operations
FPFS does not recognise criticality
Biggest concern with this is impact on ATFM performance!
Fairly obvious benefit to Airlines!
Hence need to limit number of cases.

15. Selective Amelioration (2)
Modelled random selection among flights delayed by more than 30 minutes
Biggest concern with this is impact on ATFM performance!
Graph suggests that maybe 200 flights / day could be ameliorated without significant adverse effect on ATFM performance
BUT significant differences between days and between scenarios, and need to check result in dynamic implementation
Modelled selective amelioration: - by forcing through at requested time - of a random selection of flights delayed by >30min - random samples making 0.5% to 5% of regulated demand - required delays between 0 and 20min (random choice)

16. Selective Amelioration - Conclusions
Minimal impact on ATFM performance from amelioration of up to 200 or so flights?
further validation needed
Recommend limiting number of cases by quota system
Recommended next steps
monitor and analyse current live usage
stakeholder consultation on how to distribute quota across AOs
trial implementation
200 flights is about 1% of demand.
Quota system means that AOs will only use this facility for their most critical flights

17. Overview of Strategies
“Global” Solutions -
Slot Allocation
Prioritised by:
Flight Type
Least Consumer Cost
Flight Distance
CDM Procedures for Prioritisation of Particular Flights
Integration of AO Tactical Priorities
Selective Amelioration
Airport Public Order Exceptions
Burden Sharing
Public Comment Proceedings

18. Airport Public Order Exceptions
Initial aim: when serious delays lead to risk of public order disturbances
Delegation of control from central (CFMU) to local (Airport) level
e.g. now: De-Icing Procedures
generalise: “Chaotic Situation Management”
If number of flights affected is small, use Selective Amelioration
Initial aim: when serious delays lead to risk of public order disturbances
- but can be used more generally for any case when local crisis (weather, fire, …) means prioritisation is more appropriately decided and applied locally
= Chaotic Situation Management
Decision-making delegated to a local problem manager who has best view of local situation
No simulations.
Returning to public order issue - if few flights affected...

19. Airport Public Order Exceptions (Chaotic Situation Management)
Monitoring and reporting of use
to guard against abuse or overuse
Recommended next steps
trial implementations
put in place Letters of Agreement
Abuse might amount to prioritisation of local airline’s flights by local authority
Bi-lateral letters of agreement are the existing mechanism for De-Icing procedures

20. Overview of Strategies
“Global” Solutions -
Slot Allocation
Prioritised by:
Flight Type
Least Consumer Cost
Flight Distance
CDM Procedures for Prioritisation of Particular Flights
Integration of AO Tactical Priorities
Selective Amelioration
Airport Public Order Exceptions
Burden Sharing
Public Comment Proceedings

21. Burden Sharing Applicable when capacity shortfall expected
to avoid delays, must reduce demand
all make agreed proportional reduction
AOs to decide which specific flights to cancel
Currently, national ad-hoc frameworks for crisis management
Strategic or Pre-tactical procedure
Some current examples, but use not systematic

22. Burden Sharing Trade-off of demand cut and delay saved Simulations:
implemented AO demand reduction model
applied regulations to reduce capacity
(Demand reduction model = random!)
Results averaged over several scenarios
- example regulations
- days’ traffic
Significant differences between scenarios

23. Burden Sharing - Conclusions
Implement as fully structured collaborative process
strategic or pre-tactical
Recommended next steps
refine guidelines for demand reduction - especially among smaller operators
develop collaborative procedures
apply in trial cases

24. Overview of Strategies
“Global” Solutions -
Slot Allocation
Prioritised by:
Flight Type
Least Consumer Cost
Flight Distance
CDM Procedures for Prioritisation of Particular Flights
Integration of AO Tactical Priorities
Selective Amelioration
Airport Public Order Exceptions
Burden Sharing
Public Comment Proceedings

25. Public Comment Proceedings
Strategic planning to deal with large events
capacity enhancement
demand management and prioritisation
Transparent, consensus-based planning
EAG-OSG level
Recommended next steps
analysis of events to date
consultation on guidelines for applicable events
trial procedures in real cases
Scheduling for major events can be extremely time-sensitive
- FPFS can lead to unacceptable degree of disorder.
Strategic agreement/identification of high priority flights
- e.g. ensure key personalities not late for opening ceremony!
Again - exists now in ad-hoc form,
but need “proceduralising” - systematic use!
Strategic plans may enable local prioritisation under Chaotic Situation Procedures

26. Conclusion
All strategies apply to crises, several also to chronic congestion
None appear to reduce ATFM performance
Many formalise existing procedures
Some could provide incentives for “good behaviour” by AOs
Recommended next step for many is specification of procedures and live trial
Institutional and operational issues remain to be addressed
In a crisis, makes sense to do what you can to reduce impact on operations
- but need to have agreed approaches and procedures to ensure they can be successfully applied
Further development of these is subject to
- stakeholder agreement
- competing priorities for developments of CFMU / ATFM !!