I use Flight Track to follow a flight as often as I can – at least once per week.  While real-time tracking provides a good exercise of the code, sometimes I’m not able to follow the flight.  In that case, I set it up in Flight Track for a flight I want to follow, and run some predictions.  Soon after the flight concludes, I retrieve the packets from aprs.fi and simulate the flight.

I place the packets into a file and load the file into the simulator.  To simulate the packets arriving from a radio, I send packets from a COM port on my desktop computer to my laptop where Flight Track runs.  I select a time interval between packets (1, 2, 10, 30, or 60 seconds – I can also select a custom interval).  When I click on play (the button labeled ‘>’ at the upper left), the packets are delivered to Flight Track in Track mode.

I used the simulator over the weekend for a flight using Mic-E.  I recently added Mic-E parsing and want to verify it operates correctly.  The ascent rate during the flight was incorrect (in excess of 4000 ft/min) so I investigated.

When I set up the simulation, I selected a 10 second interval.  Since Mic-E does not contain a time stamp, Flight Track assigns a time stamp internally. When it went to calculate an ascent rate, Flight Track divided the difference in altitude by the difference in time.  The result was around 4000 ft/min because the actual time between two packets was about two minutes and Flight Track used the interval I selected: 10 seconds.  I modified the Flight Simulator to use time stamps that I add to the log file, and deliver the packets based on the difference between the time stamps.  This modification provided the correct ascent rate.

A Minor Omission
When I add new functionality, I start with the Flight Review code and verify its operation before copying it to the Flight Track code.  While the code for both Flight Review and Flight Track are as similar as possible, I occasionally find something I put in one and not the other.  For example, I discovered that the Flight Track code did not place a push pin at the burst coordinates.

The Flight Simulator provides the opportunity to review flights when I can, and verify code changes have been made.  It speeds my work along so when Saturday arrives, I can enjoy the flight and deliver a good product.