Tailored Arrivals

The ideal TA is a trajectory that allows the aircraft to meet the required time at a metering fix while performing a low power descent along the optimal lateral path. However, in the case of the TA, the goal of reduced environmental impact has been balanced with operational needs such as avoidance of severe weather, terrain, and other traffic and by conformance with arrival management constraints caused by aircraft congestion.  In addition, airport and runway capacity must be maintained by precise, predictable sequencing and by coordination of arrival and departure streams. 

The Tailored Arrivals concept is depicted in Figure 1 at right, with Tailored Arrivals flights begin given altitude and speed constraints prior to beginning their descent, to allow the flights to descend with maximum emissions efficiency while still staying clear of surrounding flights and integrating into the arrival flows at the prescribed time.

The Tailored Arrival clearance is calculated by the ground system to provide the controller with a means of delivering the aircraft at its required time over a downstream fix while simultaneously satisfying all other needs.  The cleared lateral path and other constraints are communicated to individual flights prior to Top Of Descent (TOD) as part of the arrival clearance for use by the Flight Management Computer (FMC) in calculation of the descent path.  Updated meteorological information is also provided to improve flight path efficiency, and to allow more precise path calculation and timing predictability.  The clearance may include speed and altitude constraints, and the use of lateral length adjustment to increase control authority for sequencing and coordination.

Some of the primary techniques used within Tailored Arrivals clearances are graphically depicted in figures 2 and 3. In figure 2, speed control is depicted; in this case the Tailored Arrivals ground system has determined that a faster speed during the descent will allow the flight to efficiently integrate into the arrivals stream.

When larger time adjustments are needed to ensure spacing than those depicted in figure 2, the TA procedure introduces small route adjustments and uplinks these to aircraft allowing flight crews to load the customized route into the flight management system. It is most efficient to make those adjustments up high where aircraft are more efficient, rather than during the descent where the changes are much more costly in terms of emissions. This Tailored Arrivals technique is depicted in figure 3.

The resulting arrival is tailored to provide the most efficient flight path in the existing conditions, and will almost always be more efficient than that achieved with traditional tactical vectoring techniques.

A Tailored Arrival has the potential to allow the aircraft to:

• Fly an optimized descent trajectory for the given conditions while meeting a proposed time at an arrival feeder fix. This leads to reduced fuel-burn, noise and emissions while maintaining runway capacity
  
• Avoid terrain and restricted airspace while taking sequencing flow constraints into account,
  
• Reduce voice communications during arrival and approach,
  
• Improve predictability for both aircraft operator and Air Navigation Service Providers (ANSPs),
  
• Reduce pilot workload by taking full advantage of aircraft automation,
  
• Reduce controller workload by reducing the need to devise and provide discrete clearances for each arriving aircraft in order to build the required arrival stream.

 

 

 

Flight Phase Information

Figure 1

Figure 2

Figure 3