Airspace Design
In this scenario, we elaborate on the intersection of two traffic flows—one ascending and the other
descending. The perspective is from the viewpoint of the descending flow, depicting the
successive Positions of Control visited by the landing flow (refer to the left Figure).
The landing flow progresses from en-route to landing through an Upstream Position followed by two
Downstream Positions and, finally, the Terminal Maneuvering Area (TMA). Each Position is overseen
by a team of air traffic controllers (usually two). The transition of a flight between consecutive
Positions of Control involves Coordination, which is a negotiation between the two teams
regarding entering/exiting altitudes.
Generally, airspace design aims to segregate conflicting flows, as illustrated in the Figure,
where the climbing flow remains outside the four Positions, alleviating air traffic controllers of
managing this flow.
Extra Cost Induced by this Airspace Design
In our example, the separation between the two flows is achieved through a dedicated airspace
design, sparing air traffic controllers from handling conflicts between the two flows. In essence,
controllers of the four Positions only oversee the passage of the descending flow.
However, this solution comes at a cost.
Can you identify it?
In the Figure, we observe an early Top Of Descent (to enter the Downstream Position). The
margin (horizontal red arrow) signifies the extent by which the Top Of Descent could have
been delayed concerning the climbing flow.
Optimization Strategies
We've noted that the flight profile of the landing aircraft is constrained by the airspace design,
compelling the aircraft to initiate an early descent.
There are alternative methods to guide the profile of an aircraft that are less penalizing. For
instance, the landing aircraft has a Standard Terminal Arrival Route (STAR) stored in its database, and
adjusting a vertical constraint at a strategic point on the STAR can ensure that the aircraft
descends "sufficiently early" concerning the climbing flow.
Our toolset enables the performance of such adjustments on procedures; we can compute the current
extra fuel consumption and suggest a redesign of procedures with an associated fuel gain.