Route Spacing Evaluator

The Route Spacing Evaluator has been developed by EUROCONTROL to enable ATM specialists, including airspace planners, to visualise and comprehend the impact on spacing between aircraft trajectories of aircraft performing a Fly-By turn near the turn points of two parallel tracks.

The Route Spacing Evaluator:

• Allows the user to make the following inputs by means of the input fields in bold dark blue:

  • Lowest expected speed data (can be either IAS, Mach or TAS; after input of one of these variables, the other two are automatically computed taking into account Flight Level and ISA deviation): this defines the speed of the slowest aircraft in the airspace, initiating the turn at the latest possible point

  • Route data (FL, inbound and outbound courses, nominal spacing between the two parallel tracks): the inbound and outbound courses are defined by dragging the inbound and outbound areas between the parallel tracks

  • Weather data (Wind, ISA deviation)

• The tool then computes and displays the turn geometry (displayed in red) of the slowest aircraft initiating the turn at the latest possible point by applying a maximum assumed bank angle (defined by the bold dark blue input field)

Note: if the red line is not visible, it means that the turn is so close to the turn waypoint that the red line overlaps with in the inbound and outbound course

• The tool also computes and displays the turn geometry (displayed in green) of an aircraft initiating the turn at the earliest possible point as defined by the Fly-By Transition Boundary

• The tool provides information on the spacing of the two most constraining aircraft trajectories (solid red and green lines) along the turn with the maximum or the minimum value of the spacing (depending on the turn configuration) at the bisector of the turn

Purpose

The Route Spacing Evaluator is not intended to be used as a route design tool although it may be useful during the planning (pre-design) and validation (post-design) phases.

The Route Spacing Evaluator is provided on the clear understanding that EUROCONTROL makes no warranty, whether express or implied, arising by law or otherwise, assumes no responsibility to any person or persons, and disclaims any liability with respect to the use of the tool and any derivative works including but not limited to, any express or implied warranty of fitness for a particular purpose.

Turn Performance

Aircraft Fly-By turn performance is commonly influenced by the following factors:

• Prevailing wind conditions

• Design of the ATS routes - angle of turn

• Controller instructions

• Aircraft type, altitude, speed, avionics and software, as well as pilot input

Fly-By Transition Boundary

Fly-By turns should remain within the Fly-By Transition Boundary which is defined in RTCA DO-236C / EUROCAE ED-75D and calculated by this tool, as follows:

Low Altitude Transitions (below Flight Level 195):

• Groundspeed = 500 kts

• Bank Angle = Minimum(Turn Angle / 2, 23º)

Note: in this tool, a groundspeed of 350kts is used to define the earliest possible turn below Flight Level 100, which is deemed more realistic than the 500kts as assumed by RTCA DO-236C / EUROCAE ED-75D

High Altitude Transitions (above Flight Level 195):

• Groundspeed = 750 kts

• Bank Angle = 5º

• Turn initiation distance ≤ 20 NM