- A few weeks ago I heard about a pilot who had done some funky navigation, which showed up as a drawing of an aircraft when looking at his flight track from historical radar data. This looked like a fun project to put together locally in Texas.
I pitched my friend and Cirrus Owner Charlie Thompson on the idea and the next day he had already plotted and charted the 147 mile trajectory in ForeFlight, which we ultimately used to implement our 'drawing'
The idea was to take a frequently used acronym from the No Agenda Show Podcast and 'write it in the sky' by utilizing ADS-B (The latest standard in aviation that is enjoyed by hackers and makers globally) and APRS (Automatic Packet Reporting System used by Ham Radio operators) to 'drop' gps data points along out route. The initials ITM stand for "In The Morning". Listen to the podcast to get a better understanding of what that is all about :-)
Crucial to the project's success was the ability to have our data displayed on the web so people could follow along at home. In order for FlightAware.com to show our track, we had to be in the national flight system. This consisted of multiple phone calls and even FAXING a flight plan. For APRS, I brought my Yaesu FTD1 Handheld transceiver, configured to beacon every 30 seconds on the 2m band. These packets were being beaconed directly from the Handheld in the cockpit, and data included altitude, GPS position, my call sign (K5ACC) and a comment reading "ITM Flight"
- Our plan had us departing San Marcos Municipal Airport, westbound towards Fredrickberg, where we planned to have lunch.
We did a quick briefing in RedBird Aviation's coffee shop, which included a checklist of oddities we needed to track. This included me calling out turning-points to Charlie, 0.65nm before each waypoint, which Charlie had calculated to be a 'standard rate turn' into the next leg of our letters. About halfway the "T", ForeFLight lost all it's gps data on screen, although it continued to track correctly, so I made my best guesstimate based on visual measurements when to make our turns. This also had to be at the calculated a ground speed of 122 knots, meaning monitoring our speed, which accelerated to 133knots on the downwind legs.
In all, the result was above satisfactory! Sadly we only showed up in the national ATC database for a tiny bit of our flight, making tracking on FlightAware.com impossible, but the APRS data was phenomenal! You can see the track perfectly, including my drive from the city to the airport and back again.
- APRS is basically digital data being transmitted through radio waves, received by one or more ground stations, all operated by amateur volunteers and repeated (digipeated) to another ground station (if needed) connected to the internet if needed. Some of the best APRS tracks I have ever seen!
- Thanks again to Charlie and all the No Agenda Producers who helped monitor and propagate our formula.
- We also plotted the GPS data recorded on board with a Garmin to Google Earth
