Cross track distance from fly-by waypoints

When you’ve defined a proposed route in WeatherSpork you may notice that it picks a number of “proximity” fly-by stations (airports) to include along that route.  These show up on the Map view as rounded square icons like those shown below.  But how far is KMSV off of your great circle route from KBOS to KCLE to KORD?  That’s known as cross track distance (abbreviated XTK) and is defined as the closest distance from the station to the route as shown below.

Now in WeatherSpork version 4.3.0 we’ve added a cross track distance (XTK) to the route progress strip at the bottom of the Route Profile view.  These proximity stations along with those defining your route (departure, midpoints and destination) will be added to this view.   This gives you a quick indication of just how far this station is off of the route.  For example, in the Profile view below, KMSV is 27 nm from the route identified in the blue oval.  To decrease clutter in the route progress strip, cross track distances are not shown for the departure, destination and midpoint stations as shown by the red Xs below; it’s assumed that the XTK is 0 nm.

Keep in mind that the weather can be quite different at these proximity stations as compared to stations on the actual route.  The greater the distance, the more likely the variation in weather.  Keep that big weather picture in mind.

Scott Dennstaedt
Weather Systems Engineer

Scott Dennstaedt

View posts by Scott Dennstaedt
CFI and former NWS research meteorologist. Co-founder of WeatherSpork
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