This tool is intended as a simplistic illustration of the vertical interaction between arrivals and departure.

The horizontal access at the top shows nautical miles in red reducing from left to right as the aircraft descends and gets closer in track miles to the runway, the horizontal access at the bottom in blue shows nautical miles increasing from left to right as the aircraft increases its track miles after departure from the runway.

The purpose of such a graph is to determine whether the selected crossing point between SIDs and STARs is appropriate or whether the point selected is one where both aircraft on their ‘natural’ profiles would seek to be at the same level, thereby needing to level them off which is not flight efficient.

When undertaking an airspace design particularly in the terminal area, it is important for the design team to create their own graphs, which can be based on input from flight crews, or, better still, on radar data showing actual vertical performance. The correct selection of the crossing point greatly alleviates flight inefficiency that PBN so capably delivers.

The user can either adjust the red glidepath by moving it up or down on the left hand side of the graph and the blue climb gradient on the right hand side of the graph (both are initially set at 3°).  These gradients can also be adjusted by selecting Arrival and Departure text values displayed.  Once the correct gradients have been set then move the two boxes on the top and bottom off the chart to set the point of crossing.  Remember blue is departure distance and red is track distance to touchdown.  As with the climb and descent gradients, track distances can also be set manually.

The vertical separation at the crossing point is displayed to the user.