2.
Free Filing - The ability for the user to file and reasonably expect to fly pre-planned
User Preferred Trajectories (UPT) (Beatty, 1997). It is our belief that these Free Flight goals can be accomplished with a combination of a more dynamic strategic replanning capability that includes a significant airborne component and air traffic management improvements that relax some of the route and procedural inflexibility’s.
3.2 Collaborative Decision Making (CDM)
The idea of allowing all Stakeholders with vested interest to participate in decisions related to the appropriate course of action is at the heart of the Collaborative Decision-Making (CDM) paradigm. In a nutshell, the CDM paradigm shift allows airline dispatchers to work interactively with traffic flow managers to draw-down their own demand on airports when the capacity of an airport changes. Without CDM, if an airport were to experience a reduction in capacity (i.e., reduction in the Airport Arrival Rate-AAR) it is up to ATC to use measures, sometimes draconian actions such as ground stops, to reduce the demand on the facility prior to an airborne holding mess developing over the affected airport. A good example of this sort of reduced capacity is a transient period of low visibility, such as morning fog, that will reduce the AAR. In the past, ATC might issue a ground stop affecting all aircraft that were going to arrive during the period of forecasted fog. The problem with this approach is that it allows no flexibility to airlines trying to recover from this irregular operation. The affected aircraft are in effect quarantined; they can do nothing else but wait for the ground stop to be removed. In the current CDM paradigm, the forecasted reduction in capacity is broadcast over a wide-area network (the AOCnet) from ATC to all participating airlines. A specific time limit is placed on the airlines to draw-down demand. If the airlines accommodate the reduced capacity by reducing their own demand (thus reducing the aggregate demand on the arrival rate) prior to the time limit, then ATC will not need to enact any measures, such as a ground stop. This freedom allows the airlines to reduce the impact of the reduced capacity at one airport on their overall schedule as they see fit.
An example serves to illustrate the point. Imagine that SFO is forecast to experience fog between 6:00-8:00am, effectively reducing the AAR by half. Further imagine that Airline XYZ, has two flights from LAX to SFO scheduled to arrive between 6:00 and 8:00am. If a ground stop were issued by ATC, then those aircraft will load the passengers on the two scheduled flights and occupy the departure gate at LAX until they receive clearance to leave. This not only frustrates the paying passenger, it effectively blocks the gates at LAX which were expected to be cleared so that incoming aircraft could use them. With the flexibility afforded by CDM, the airline might choose to cancel outright one of the two flights, load as many passengers off the canceled flight onto the one that will proceed to SFO, and offer future travel vouchers for those passengers willing to wait for a later flight. This allows at least one aircraft to proceed on to the destination, and now leaves the airline only trying to recover from having one aircraft, and associated crew, out of place instead of two. What has occurred with the shift to CDM is it allows the Stakeholder that is most concerned with the outcome to control what happens.
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